Abstract: A resistive random access memory is provided. The resistive random access memory includes a substrate, a first electrode formed on the substrate, a second electrode formed on the substrate and located on one side of the first electrode, a first metal oxide layer formed on sidewalls of the second electrode, a first control layer formed between the first electrode and the first metal oxide layer, and a second control layer formed on the first control layer and located between the first electrode and the first metal oxide layer.

Abstract: Provided is a resistive random access memory (RRAM) including at least one memory cell. The at least one memory cell includes a top electrode, a bottom electrode, a data storage layer, an oxygen gettering layer, a first barrier layer, and an oxygen supplying layer. The data storage layer is disposed between the top electrode and the bottom electrode. The oxygen gettering layer is disposed between the data storage layer and the top electrode. The first barrier layer is disposed between the oxygen gettering layer and the data storage layer. The oxygen supplying layer is disposed between the oxygen gettering layer and the top electrode and/or between the oxygen gettering layer and the first barrier layer.

Abstract: A multi-bit resistive random access memory cell includes a plurality of bottom electrodes, a plurality of dielectric layers, a top electrode and a resistance layer. The bottom electrodes and the dielectric layers are interleaved layers, each of the bottom electrodes is sandwiched by the dielectric layers, and a through hole penetrates through the interleaved layers. The top electrode is disposed in the through hole. The resistance layer is disposed on a sidewall of the through hole and is between the top electrode and the interleaved layers, thereby the top electrode, the resistance layer and the bottom electrodes constituting a multi-bit resistive random access memory cell. The present invention also provides a method of forming the multi-bit resistive random access memory cell.

Abstract: A semiconductor device includes a stack structure on a substrate, the stack structure including alternating gate electrodes and insulating layers stacked along a first direction, a vertical opening through the stack structure along the first direction, the vertical opening including a channel structure having a semiconductor layer on an inner sidewall of the vertical opening, and a variable resistive material on the semiconductor layer, a vacancy concentration in the variable resistive material varies along its width to have a higher concentration closer to a center of the channel structure than to the semiconductor layer, and an impurity region on the substrate, the semiconductor layer contacting the impurity region at a bottom of the channel structure.

Abstract: One illustrative device disclosed herein includes a layer of insulating material with its upper surface positioned at a first level and a recessed conductive interconnect structure positioned at least partially within the layer of insulating material, wherein a recessed upper surface of the recessed conductive interconnect structure is positioned at a second level that is below the first level. In this example, the device also includes a conductive cap layer positioned on the recessed upper surface of the recessed conductive interconnect structure, wherein an upper surface of the conductive cap layer is substantially co-planar with the upper surface of the layer of insulating material and a memory cell positioned above the conductive cap layer, wherein the memory cell comprises a lower conductive material that is conductively coupled to the conductive cap layer.

Abstract: A memory device includes a word line, a bit line intersecting the word line, and a memory cell at an intersection of the word line and the bit line. The memory cell includes a first electrode connected to the word line; a second electrode connected to the bit line; and a selective element layer between the first electrode and the second electrode. The selective element layer includes one of Ge—Se—Te, Ge—Se—Te—As, and Ge—Se—Te—As—Si, and a composition ratio of arsenic (As) component of each of the Ge—Se—Te—As and the Ge—Se—Te—As—Si being greater than 0.01 and less than 0.17.

Abstract: Resistive memory with core and shell oxides and interface dipoles for controlled filament formation is provided. In one aspect, a ReRAM device includes at least one ReRAM cell having a substrate; a bottom electrode disposed on the substrate; spacers formed from a low group electron negativity material disposed on the bottom electrode; a core formed from a high group electron negativity material present between the spacers; and a top electrode over and in contact with the spacers and the core, wherein a combination of the low group electron negativity material for the spacers and the high group electron negativity material for the core generates an interface dipole pointing toward the core. Methods of forming and operating a ReRAM device are also provided.

Abstract: A memory device includes a dielectric layer, a bottom electrode, an inter-metal dielectric (IMD) layer, a phase change element in the IMD layer, and a top electrode. The bottom electrode is in the dielectric layer. The IMD layer is over first dielectric layer. The phase change element is in the IMD layer. The top electrode is over the phase change element and is separated from the dielectric layer by at least an air gap free of materials of the IMD layer and the phase change element.

Abstract: A resistive random access memory device includes a first electrode; a solid electrolyte made of metal oxide extending onto the first electrode; a second electrode able to supply mobile ions circulating in the solid electrolyte made of metal oxide to the first electrode to form a conductive filament between the first and second electrodes when a voltage is applied between the first and second electrodes; an interface layer including a transition metal from groups 3, 4, 5 or 6 of the periodic table and a chalcogen element; the interface layer extending onto the solid electrolyte made of metal oxide, the second electrode extending onto the interface layer.

Abstract: A method includes forming a dielectric layer over a conductive layer, and forming a sidewall spacer in an opening in the dielectric layer. The opening exposes a portion of the conductive layer. A bottom electrode layer is formed over the conductive layer and the sidewall spacer. A phase change material layer is formed over the bottom electrode layer, and a top electrode layer is formed over the phase change material layer. In an embodiment, the method includes recess etching the bottom electrode layer before forming the phase change material layer.

Abstract: A method used in forming a memory array comprises forming digitlines above and electrically couple to memory cells there-below. The digitlines are laterally-spaced relative one another in a vertical cross-section. An upwardly-open void-space is laterally-between immediately-adjacent of the digitlines in the vertical cross-section. Conductive material of the digitlines is covered with masking material that is in and less-than-fills the upwardly-open void-spaces. The masking material is removed from being directly above tops of the digitlines to expose the conductive digitline material and to leave the masking material over sidewalls of the conductive digitline material in the upwardly-open void-spaces. Insulative material is selectively grown from the exposed conductive digitline material relative to the masking material across the upwardly-open void-spaces to form covered void-spaces there-from between the immediately-adjacent digitlines in the vertical cross-section.

Abstract: Systems and methods are provided for providing a passively switched light source. An integrated optical component includes a photonic material and a phase change material in direct contact with the photonic material. A light source provides light into the integrated optical component. The light interacts with the phase change material such that an index of refraction of the phase change material depends on the intensity of the light within the integrated optical component as to provide a passive change to a parameter of the integrated optical component.

Abstract: Systems, devices, and methods related to or that employ chalcogenide memory components and compositions are described. A component of a memory cell, such as a selector device, storage device, or self-selecting memory device, may be made of a chalcogenide material composition. A chalcogenide material may have a composition that includes one or more elements from the boron group, such as boron, aluminum, gallium, indium, or thallium. The chalcogenide material, for instance, may have a composition of selenium, germanium, and at least one of boron, aluminum, gallium, indium, or thallium. The chalcogenide material may in some cases also include arsenic, but may in some cases lack arsenic.

Abstract: The present disclosure provides a semiconductor device structure with an air gap structure and a method for forming the semiconductor device structure. The semiconductor device structure includes a first conductive contact and a second conductive contact disposed over a semiconductor substrate. The semiconductor device structure also includes a first dielectric layer surrounding the first conductive contact and the second conductive contact, and a second dielectric layer disposed over the first conductive contact, the second conductive contact and the first dielectric layer. The first dielectric layer is separated from the semiconductor substrate by a first air gap structure, the first dielectric layer is separated from the second dielectric layer by a second air gap structure, and the air gap structures reduce capacitive coupling between conductive features.

Abstract: The present disclosure, in some embodiments, relates to an integrated chip. The integrated chip includes a lower inter-level dielectric (ILD) structure surrounding a plurality of lower interconnect layers over a substrate. An etch stop material is disposed over the lower ILD structure. A bottom electrode is arranged over an upper surface of the etch stop material, a data storage structure is disposed on an upper surface of the bottom electrode and is configured to store a data state, and a top electrode is disposed on an upper surface of the data storage structure. A first interconnect via contacts the upper surface the bottom electrode and a second interconnect via contacts the top electrode.

Abstract: The present disclosure relates to a resistive random access memory device and a preparing method thereof.

Abstract: A semiconductor storage device includes a first conductive layer, a second conductive layer, and a first chalcogen layer provided therebetween. A third conductive layer and a fourth conductive layer have a second chalcogen layer provided therebetween. The second chalcogen layer contains tellurium (Te). When a minimum value and a maximum value of a composition ratio of tellurium in the second chalcogen layer observed along the first direction are a first minimum value and a first maximum value, respectively, the first minimum value is observed at a position closer to the third conductive layer than a center position in the first direction of the second chalcogen layer, and the first maximum value is observed at a position closer to the fourth conductive layer than the center position in the first direction of the second chalcogen layer.

Abstract: Aspects of the present technology are directed toward Integrated Circuits (IC) including a plurality of trenches disposed in a substrate about a set of silicide regions. The trenches can extend down into the substrate below the set of silicide regions. The silicide regions can be formed by implanting metal ions into portions of a substrate exposed by a mask layer with narrow pitch openings. The trenches can be formed by selectively etching the substrate utilizing the set of silicide regions as a trench mask. An semiconductor material with various degree of crystallinity can be grown from the silicide regions, in openings that extend through subsequently formed layers down to the silicide regions.

Abstract: A nonvolatile resistive switching memory comprising an insulating substrate, a lower electrode, a lower graphene barrier layer, a resistive switching functional layer, an upper graphene barrier layer, and an upper electrode, wherein the lower and/or the upper graphene barrier layer is/are capable of preventing the metal ions/atoms in the lower/upper metal electrode from diffusing into the resistive switching functional layer under an applied electric field.

Abstract: A resistive random access memory structure includes a bottom electrode; a variable resistance layer disposed on the bottom electrode; a top electrode disposed on the variable resistance layer; a protection layer surrounding the variable resistance layer, wherein a top surface of the protection layer and a top surface of the top electrode are coplanar; and an upper interconnect structure disposed on the top electrode, wherein the upper interconnect structure is electrically connected to the top electrode and directly contacts a sidewall of the protection layer.

Abstract: An analog neuromorphic circuit is disclosed having resistive memories that provide a resistance to each corresponding input voltage signal. Input voltages are applied to the analog neuromorphic circuit. Each input voltage represents a vector value that is a non-binary value included in a vector that is incorporated into a dot-product operation with weighted matrix values included in a weighted matrix. A controller pairs each resistive memory with another resistive memory. The controller converts each pair of resistance values to a single non-binary value. Each single non-binary value is mapped to a weighted matrix value included in the weighted matrix that is incorporated into the dot-product operation with the vector values included in the vector. The controller generates dot-product operation values from the dot-product operation with the vector and the weighted matrix where each dot-product operation is a non-binary value.

Abstract: A memory device may be provided, including a base layer, an insulating layer, a first electrode, a switching element, a capping element and a second electrode. The insulating layer may be arranged over the base layer and may include a recess having opposing side walls. The first electrode may be arranged at least partially within the recess of the insulating layer and along the opposing side walls of the recess of the insulating layer. The switching element may be arranged at least partially within the recess of the insulating layer and along the first electrode. The capping element and the second electrode may be arranged at least partially within the recess of the insulating layer. The capping element may be arranged between the second electrode and the switching element, and a part of the second electrode may extend across the capping element to contact the switching element.

Abstract: Subject matter disclosed herein may relate to fabrication of a correlated electron material (CEM) switch. In particular embodiments, an insulative material may be formed on or over a sidewall portion of a conductive contact region. The insulative material may insulate the conductive contact region from resputtered CEM occurring during a physical etch of a CEM film.

Abstract: A display substrate, a method for manufacturing the display substrate, and a display device are provided in the present disclosure. The display substrate includes: a substrate; a first insulation layer on the substrate; a first signal line on a side of the first insulation layer distal to the substrate; a second insulation layer covering the first signal line; and a second signal line on a side of the second insulation layer distal to the substrate, the second signal line overlapping with the first signal line at an overlap region. A concave portion is formed in the first insulation layer. At least at the overlap region, the first signal line is in the concave portion.

Abstract: An oxidation barrier for non-volatile memory with materials sensitive to temperature and/or cross contamination (e.g., chalcogenide materials) are described The barrier can be formed, for example, around the boundaries of a non-volatile memory tile (also known as a block or sub-array). For example, a non-volatile memory device can include an oxidation barrier on a side wall of a trench between adjacent memory tiles.

Abstract: A contact via structure vertically extending through an alternating stack of insulating layers and electrically conductive layers is provided in a staircase region having stepped surfaces. The contact via structure is electrically isolated from each electrically conductive layer of the alternating stack except for an electrically conductive layer that directly underlies a horizontal interface of the stepped surfaces.

Abstract: Memory devices having a plurality of memory cells, with each memory cell including a phase change material having a laterally constricted portion thereof. The laterally constricted portions of adjacent memory cells are vertically offset and positioned on opposite sides of the memory device. Also disclosed are memory devices having a plurality of memory cells, with each memory cell including first and second electrodes having different widths. Adjacent memory cells have the first and second electrodes offset on vertically opposing sides of the memory device. Methods of forming the memory devices are also disclosed.

Abstract: Provided are embodiments for a semiconductor device that includes a bottom contact; a multi-layer bottom electrode formed over the bottom contact; a magnetic tunnel junction stack formed over the multi-layer bottom electrode; and a top electrode formed over the magnetic tunnel junction stack. Also provided are embodiments for forming the semiconductor device described herein.

Abstract: Some embodiments include a memory array having vertically-stacked memory cells. Each of the memory cells includes a transistor coupled with a charge-storage device, and each of the transistors has channel material with a bandgap greater than 2 electron-volts. Some embodiments include a memory array having digit lines extending along a vertical direction and wordlines extending along a horizontal direction. The memory array includes memory cells, with each of the memory cells being uniquely addressed by combination of one of the digit lines and one of the wordlines. Each of the memory cells includes a transistor which has GaP channel material. Each of the transistors has first and second source/drain regions spaced from one another by the GaP channel material. The first source/drain regions are coupled with the digit lines, and each of the memory cells includes a capacitor coupled with the second source/drain region of the associated transistor. Other embodiments are disclosed.

Abstract: A semiconductor device with resistive memory includes a bottom electrode disposed on a base structure, the bottom electrode having a structure that tapers up from the base structure to a tip of the bottom electrode. The semiconductor device also includes sidewall spacers on the sides of the bottom electrode, an interlayer dielectric deposition (ILD) outside the sidewall spacers, and a top dielectric layer disposed over the bottom electrode, and the sidewall spacers. The semiconductor device further includes a top electrode deposited over the bottom electrode within the sidewall spacers. A filament formation region is formed at the tip of the bottom electrode.

Abstract: A semiconductor structure includes an oxide ReRAM co-integrated with a drain region of a field effect transistor (FET). The oxide ReRAM has a tip region defined by a pointed cone that contacts a faceted upper surface of the drain region of the FET. Such a tip region enhances the electric field of the oxide ReRAM and thus helps to control forming of the conductive filament of the oxide ReRAM.

Abstract: A memory device includes a plurality of memory cells, and an isolation material portion located between the memory cells. The isolation material portion includes at least one ovonic threshold switch material portion.

Abstract: A method to form a 3D semiconductor device, the method including: providing a first level including first circuits, the first circuits including first transistors and first interconnection; preparing a second level including a silicon layer; performing growth of an epitaxial layer on top of the silicon layer, the epitaxial layer including non-silicon atoms; forming second circuits over the second level, the second circuits including second transistors and second interconnection; transferring and then bonding the second level on top of the first level; and then thinning the second level to a thickness of less than ten microns, where the bonding includes oxide to oxide bonds.

Abstract: According to one embodiment, a semiconductor storage device includes a first wiring, a first resistance change element which is connected to the first wiring, a first nonlinear element which is connected to the first resistance change element, and a second wiring which is connected to the first nonlinear element. In a read operation for the first resistance change element, a voltage between the first wiring and the second wiring increases to a first voltage, and after the voltage between the first wiring and the second wiring increases to the first voltage, the voltage between the first wiring and the second wiring increases to a second voltage which is larger than the first voltage.

Abstract: A resistive memory device including: first conductive lines extending in a first direction; second conductive lines extending in a second direction crossing the first direction; and memory cells connected to the first conductive lines and the second conductive lines, wherein the memory cells include: a first memory cell including a first resistive memory layer and a first heating electrode layer, the first heating electrode layer includes a first contact surface in contact with the first resistive memory layer and the first contact surface has a first contact resistance; and a second memory cell including a second resistive memory layer and a second heating electrode layer, the second heating electrode layer includes a second contact surface in contact with the second resistive memory layer and the second contact surface has a second contact resistance different from the first contact resistance.

Abstract: A method for manufacturing a resistive random access memory includes depositing a layer made of an active material of variable electrical resistance on a substrate containing a first electrode, forming a lower electrode; depositing an electrically conductive layer on the active material layer; etching the electrically conductive layer so as to delimit a second electrode, forming an upper electrode, facing the lower electrode; exposing at least one flank of the upper electrode to an ion beam inclined with respect to the normal to the substrate by an angle (?) comprised between 20° and 65°, so as to implant the ions in a portion of the active material layer adjacent to the flank and located under the upper electrode, the ion implantation conditions being chosen so as to create defects in the structure of the active material and to obtain an average implantation width comprised between 5 nm and 10 nm.

Abstract: A method includes providing a substrate having a conductive column, a dielectric layer over the conductive column, and a plurality of sacrificial blocks over the dielectric layer, the plurality of sacrificial blocks surrounding the conductive column from a top view; depositing a sacrificial layer covering the plurality of sacrificial blocks, the sacrificial layer having a dip directly above the conductive column; depositing a hard mask layer over the sacrificial layer; removing a portion of the hard mask layer from a bottom of the dip; etching the bottom of the dip using the hard mask layer as an etching mask, thereby exposing a top surface of the conductive column; and forming a conductive material inside the dip, the conductive material being in physical contact with the top surface of the conductive column.

Abstract: A chalcogenide material and an electronic device are provided. The chalcogenide material may include 1-10 atomic percent (at %) of silicon, 10-20 at % of germanium, 25-35 at % of arsenic, 40-50 at % of selenium, and 1-10 at % of tellurium. The electronic device may include a switching element including a chalcogenide material, the chalcogenide material including 1-10 atomic percent (at %) of silicon, 10-20 at % of germanium, 25-35 at % of arsenic, 40-50 at % of selenium, and 1-10 at % of tellurium. The electronic device may further include a first electrode electrically coupled to the switching element and a second electrode electrically coupled to the switching element.

Abstract: A vertical flash device (e.g., such as a field effect transistor, charge trap gate transistor, or charge trap flash device) is placed in series with a selector device. The selector's threshold voltage may be modulated depending upon the channel resistance of the flash device allowing for the storage of a state via the selector device. In this manner, the selector device may exhibit a voltage-dependent volatile resistance state change that occurs between a first state of said selector device and a second state of said selector device. A first binary value can be represented by the first state of the selector device, and a second binary value can be represented by the second state of the selector device.

Abstract: The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a substrate having a plurality of doped regions; a plurality of silicide pads disposed respectively over the plurality of doped regions; and a plurality of conductive contacts disposed respectively over the plurality of silicide pads. The plurality of conductive contacts comprise a plurality of nanowires, a conductive liner disposed over the plurality of nanowires, and a conductor disposed over the conductive liner.

Abstract: Techniques for fabricating a volatile memory structure having a transistor and a memory component is described. The volatile memory structure comprises the memory component formed on a substrate, wherein a first shape comprising one or more pointed edges is formed on a first surface of the memory component. The volatile memory structure further comprises transistor formed on the substrate and electrically coupled to the memory component to share operating voltage, wherein operating voltage applied to the transistor flows to the memory component.

Abstract: A semiconductor device includes a first vertical field effect transistor (VFET) formed on a substrate, and including a first fin and a first gate formed on the first fin, a second VFET formed on the substrate and connected to the first VFET, and including a second fin and a second gate formed on the second fin, and a third VFET formed on the substrate and including a third fin, the first gate being formed on the third fin.

Abstract: An electronic device including a semiconductor memory is provided to include a mat region comprising a plurality of memory cells, each including a second transistor; a first switching region located at a side of the mat region and including first transistors; and a second switching region located at the other side of the mat region and including third transistors, wherein the second transistors comprise: a plurality of second active regions; and a plurality of second gate structures extending in the first direction to cross the second active regions, wherein each second active regions is divided into a first side portion, a middle portion and a second side portion that are arranged alternately and repeatedly in the first direction, wherein the first transistors and the third transistors include their active regions and gate structures which are arranged in the same manner as those of the second transistors.

Abstract: A circuit according to the present application includes a diode or other non-linear device coupled to a heating element of a phase-change material (PCM) radio frequency (RF) switch. The diode or other non-linear device allows an amorphizing pulse or a crystallizing pulse to pass to a first terminal of the heating element. The diode or other non-linear device substantially prevents a pulse generator providing the amorphizing pulse or crystallizing pulse from interfering with RF signals at RF terminals of the PCM RF switch. In an array of PCM cells each including a diode or other non-linear device, the diode or other non-linear device substantially prevents sneak paths that would otherwise enable an amorphizing or crystallizing pulse intended for a heating element of a selected cell of the array to be provided to heating elements of unselected cells of the array.

Abstract: A method of fabricating an access device in a crosspoint memory array structure during BEOL processing includes: forming at least a first doped semiconductor layer on an upper surface of a first conductive layer, the first doped semiconductor layer being in electrical connection with the first conductive layer; exposing at least a portion of the first doped semiconductor layer to a directed energy source to cause localized annealing in the first doped semiconductor layer to activate a dopant of a first conductivity type in the first doped semiconductor layer, thereby converting at least a portion of the first doped semiconductor layer into a polycrystalline layer; forming a second conductive layer over a least a portion of the first doped semiconductor layer; and etching the first doped semiconductor layer and the first and second conductive layers to form an access device that is self-aligned with the first and second conductive layers.

Abstract: A variable resistance non-volatile memory device can include a semiconductor substrate and a plurality of first conductive lines each extending in a first direction perpendicular to the semiconductor substrate and spaced apart in a second direction on the semiconductor substrate. A second conductive line can extend in the second direction parallel to the semiconductor substrate on a first side of the plurality of first conductive lines and a third conductive line can extend in the second direction parallel to the semiconductor substrate on a second side of the plurality of first conductive lines opposite the first side of the plurality of first conductive lines.

Abstract: The present disclosure provides a semiconductor structure forming method, including: providing a base, a first mask layer and a second mask layer located at the top of the first mask layer being formed on the base, and the second mask layer internally having a first opening, a second opening and a third opening; forming first side wall layers on a side wall of the first opening, a side wall of the second opening and a side wall of the third opening; forming a first pattern layer filling the first opening, the second opening and the third opening, the first pattern layer internally having a first groove; etching to remove the second mask layer located between the second opening and the third opening along the bottom of the first groove, so as to form fourth openings located between adjacent first side wall layers; and by using the second mask layer and the first side wall layers as masks, etching the first mask layer below the first opening, the second opening, the third opening and the fourth openings, so as

Abstract: A memory structure includes a first dielectric layer, having a first top surface, over a conductive structure. A first opening in the first dielectric layer exposes an area of the conductive structure, and has an interior sidewall. A first electrode structure, having a first portion and a second portion, is over the exposed area of the conductive structure. The second portion extends upwardly along the interior sidewall. A resistance variable layer is disposed over the first electrode. A second electrode structure, having a third portion and a fourth portion, is over the resistance variable layer. The third portion has a second top surface below the first top surface of the first dielectric layer. The fourth portion extends upwardly along the resistance variable layer. A second opening is defined by the second electrode structure. At least a part of a second dielectric layer is disposed in the second opening.

Abstract: A method for repairing a composite structure. A damaged portion of a first facesheet of the structure is removed, forming a hole in the first facesheet. A damaged portion of the underlying core is removed to form a cavity in the sandwich. If the second facesheet is damaged, the damaged section is removed, and covered and sealed with a facesheet repair section. If the core material is an open-cell material, a dam is formed around the perimeter of the cavity, to act as a barrier between the cavity and the core material. The cavity is at least partially filled with a photomonomer resin, which then is illuminated through a mask with collimated light to form a truss structure in the cavity. Residual photomonomer resin is removed, and a facesheet repair section is bonded over the hole in the first facesheet.

Abstract: A radio frequency (RF) switch includes a heating element, an aluminum nitride layer situated over the heating element, and a phase-change material (PCM) situated over the aluminum nitride layer. An inside segment of the heating element underlies an active segment of the PCM, and an intermediate segment of the heating element is situated between a terminal segment of the heating element and the inside segment of the heating element. The aluminum nitride layer situated over the inside segment of the heating element provides thermal conductivity and electrical insulation between the heating element and the active segment of the PCM. The aluminum nitride layer extends into the intermediate segment of the heating element and provides chemical protection to the intermediate segment of the heating element, such that the intermediate segment of the heating element remains substantially unetched and with substantially same thickness as the inside segment.