Abstract: Provided are a HJT cell having high photoelectric conversion efficiency and a method for preparing the same. The HJT cell includes an N-type crystalline silicon wafer. An intrinsic amorphous silicon layer, a SiO2 layer, a C-doped SiO2 layer, a doped N-type amorphous silicon layer, a TCO conductive layer and an electrode are sequentially disposed on a front surface of the N-type crystalline silicon wafer. An intrinsic amorphous silicon layer, a SiO2 layer, a C-doped SiO2 layer, a doped P-type amorphous silicon layer, a TCO conductive layer and an electrode are sequentially disposed on a back surface of the N-type crystalline silicon wafer. The doped P-type amorphous silicon layer includes a lightly B-doped amorphous silicon layer and a heavily B-doped amorphous silicon layer.

Abstract: Provided is an indium phosphide substrate, a semiconductor epitaxial wafer, a method for producing an indium phosphide single-crystal ingot and a method for producing indium phosphide substrate capable of suppressing concave defects. An indium phosphide substrate has a diameter of 100 mm or less, and at least one of surfaces has zero concave defects detected in the topography channel, by irradiating a laser beam of 405 nm wavelength with S-polarized light on the surface.

Abstract: Provided is a light-emitting device including an organic light-emitting element and a control unit that controls the organic light-emitting element. The organic light-emitting element includes a first electrode, a second electrode, and an organic light-emitting layer which is disposed between the first electrode and the second electrode and in which separation of charges occurs due to incidence of excited light. The control unit changes a potential difference between the first electrode and the second electrode so that recoupling of the charges occurs, in a second period after passage of a delay period from a first period in which the excited light is incident to the organic light-emitting layer.

Abstract: Provided is a photovoltaic module, including: a plurality of solar cell strings arranged at intervals and each including a front surface and a rear surface arranged opposite to each other; a first encapsulation adhesive film and a back panel located on the rear surface of the solar cell string; and first embossing structures provided on one side of the back panel away from the first encapsulation adhesive film. An angle ? between a side surface of the first embossing structure and a plane of the back panel is in a range from 42° to 80°.

Abstract: A wireless optical power transmission system comprising a transmitter and receiver, the transmitter comprising a laser emitting a beam, a scanning mirror for steering the beam towards said receiver and a control unit receiving signals from a detection unit on the receiver and controlling the beam power and the scanning mirror. The receiver has a photovoltaic cell having a bandgap energy of 0.75-1.2 e V, with a plurality of conductors on abeam receiving surface. A cover layer of material blocking illumination of wavelengths outside that of the laser, is disposed on the photovoltaic cell. The cover layer may have anti-reflective coatings on its top and bottom surfaces. The detection unit thus generates a signal representing the power of the laser beam impinging upon the receiver, independent of illuminations other than that of said laser beam. The control unit thus can maintain the laser power impinging on the receiver.

Abstract: A photovoltaic device is presented. The photovoltaic device includes a layer stack; and an absorber layer is disposed on the layer stack. The absorber layer comprises selenium, wherein an atomic concentration of selenium varies across a thickness of the absorber layer. The photovoltaic device is substantially free of a cadmium sulfide layer.

Abstract: The hybrid perovskite solar cell with an organoselenium-based polymer hole transport layer includes an optically transparent first electrode layer, an electron transport layer, and a perovskite layer. The electron transport layer is sandwiched between the optically transparent first electrode layer and the perovskite layer. The hybrid perovskite solar cell with an organoselenium-based polymer hole transport layer further includes a hole transport layer and a second electrode layer. The perovskite layer is sandwiched between the electron transport layer and the hole transport layer, and the hole transport layer is sandwiched between the perovskite layer and the second electrode layer. The hole transport layer is formed from an organoselenium-based polymer.

Abstract: Provided is a glass film-resin composite which makes it possible to obtain a long-length (e.g., 500 m or more-long) glass roll. The glass film-resin composite comprises a glass film, and a resin tape laminated to at least one surface of the glass film through an adhesive, wherein the width 1 (mm) of the resin tape satisfies the following formula (1). l ? ? ? a ? E g ? t g E p ? t p ( 1 ) (where: a represents a reinforcement coefficient (mm*(?m)1/2) which is 1.10 or more; Eg represents the Young's modulus (GPa) of the glass film; Ep represents the Young's modulus (GPa) of the resin tape; tg represents the thickness (?m) of the glass film; and tp represents the thickness (?m) of the resin tape.

Abstract: An organic photovoltaic device comprises a substrate, a reflector positioned over the substrate, a first electrode positioned over at least a first portion of the reflector, a polaritonic antenna layer positioned over a second portion of the reflector different from the first portion, electrically connected to the first electrode, and at least one unit reaction cell positioned over at least part of the first electrode, the at least one unit reaction cell comprising a heterojunction layer comprising a donor material and an acceptor material, positioned over the first electrode, and a second electrode positioned over the heterojunction, wherein the polaritonic antenna and the reflector are configured to convert incoming photonic energy to polaritons. A method of fabricating an organic photovoltaic device is also disclosed.

Abstract: A solar cell, and methods of fabricating said solar cell, are disclosed. The solar cell can include a first emitter region over a substrate, the first emitter region having a perimeter around a portion of the substrate. A first conductive contact is electrically coupled to the first emitter region at a location outside of the perimeter of the first emitter region.

Abstract: Systems and methods for generating electrical current from at least one photovoltaic cell is described herein. The photovoltaic cell may be disposed over a display of an electronic device. The photovoltaic cell may comprise first and second conductive layers and a photovoltaic layer. The first conductive layer may be etched such that a width of the metal layer is less than a width of the photovoltaic layer providing visibility to the display disposed below. In some embodiments, a capacitive touch sensor is disposed between the metal layer and the absorber layer for providing interaction with a user.

Abstract: A method for manufacturing a photovoltaic device includes fabricating a first photovoltaic device portion with a first perovskite material layer having a first face, and fabricating a second photovoltaic device portion with a second perovskite material layer having a second face. Then first photovoltaic device portion and the second photovoltaic device portion are arranged such that the first face is in contact with the second face. Finally, the first photovoltaic device portion and second photovoltaic device portion are compressed at a pressure sufficient to fuse the first perovskite material to the second perovskite material.

Abstract: A high efficiency configuration for a solar cell module comprises solar cells arranged in an overlapping shingled manner and conductively bonded to each other in their overlapping regions to form super cells, which may be arranged to efficiently use the area of the solar module.

Abstract: A measurement method of subcell photocurrents and a matching degree of the subcell photocurrents of a multi-junction photovoltaic cell is provided. The measurement method includes measuring an I-V characteristic of the multi-junction photovoltaic cell; and measuring currents corresponding to respective current steps in an I-V curve to obtain approximate values of short-circuit currents of subcells in the multi-junction photovoltaic cell, and then calculating a mismatching degree of the multi-junction photovoltaic cell using step currents. According to the measurement method, a current mismatching degree of the multi-junction photovoltaic cell is obtained by calculating the mismatching degree of the step currents occurring in the I-V curve. The measurement method is rapid and simple, the measurement method avoids complicated and time-consuming processes where the subcell photocurrents are calculated based on a standard light source spectrum integral with bias lights applied.

Abstract: Photovoltaic (PV) cell structures are disclosed. In one example embodiment, a PV cell includes an emitter layer, a base layer adjacent to the emitter layer, and a back surface field (BSF) layer adjacent to the base layer. The BSF layer includes a first layer, and a second layer adjacent to the first layer. The first layer includes a first material and the second layer includes a second material different than the first material.

Abstract: A method for determining an electrical model of a string of photovoltaic modules from a characteristic I(V) of the string includes detecting a first linear zone and a second linear zone of the characteristic I(V); initialising the parameters of a non-by-pass electrical model corresponding to a first operating condition, called a non-by-pass condition; optimising the parameters of the non-by-pass electrical model from a reference characteristic I(Vref) equal to I(V), determining the parameters of the electrical model corresponding to a second operating condition, called a by-pass condition, in order to obtain a by-pass electrical model from the characteristic determining, from the characteristic I(V) the best model among the non-by-pass model and the by-pass model.

Abstract: Described herein are heterogeneous materials comprising a mixture of a first n-type semiconductor and a second n-type semiconductor. The first n-type semiconductor may be a single or plural phase TiO2 material. The second n-type semiconductor includes a metal titanate and/or a noble metal. Upon activation with ultraviolet light, the photocatalytic material mixtures described herein efficiently decompose volatile chemical compounds. Furthermore, the photocatalytic materials disclosed herein are observably more stable, relative to known semiconductor materials, to inactivation by deposition.

Abstract: A photovoltaic device (10) comprising a photoactive body between two electrodes (contact 1, contact 2). The body comprises semiconductor particles (24) embedded in a semiconductor matrix (22). The particles and matrix are electronically or optically coupled so that charge carriers generated in the particles are transferred directly or indirectly to the matrix. The matrix transports positive charge carriers to one of the electrodes and negative charge carriers to the other electrode. The particles are configured so that they do not form a charge carrier transport network to either of the electrodes and so perform the function of charge carrier generation but not charge carrier transport.

Abstract: The present invention provides a hybrid ferroelectric discotic liquid crystal solar cell by incorporating an electrolyte composition for improving power conversion efficiency of the solar cell. The hybrid ferroelectric (FE) discotic liquid crystal solar cell comprises a first layer of n-type inorganic semiconductor deposited on conductive fluorine doped tin oxide (FTO) glass plate 101, a second thin layer of light absorbing inorganic sensitizer 103; wherein the inorganic sensitizer strained titania FTO glass-plate acts as a photo anode, a third layer of ferroelectric discotic liquid crystal electrolyte 104 applied between the photo anode and a photo cathode and a fourth layer of reflective platinum deposited FTO glass-plate 105 configured to act as the photo cathode.

Abstract: A photovoltaic device is presented. The photovoltaic device includes a buffer layer disposed on a transparent conductive oxide layer; a window layer disposed on the buffer layer; and an interlayer interposed between the transparent conductive oxide layer and the window layer. The interlayer includes a metal species, wherein the metal species includes gadolinium, beryllium, calcium, barium, strontium, scandium, yttrium, hafnium, cerium, lutetium, lanthanum, or combinations thereof. A method of making a photovoltaic device is also presented.

Abstract: For the economical and energy-efficient use of a PV system having upright, in particular bifacial, PV modules and to substantially avoid shading of the PV modules, a supporting structure which is simple to manufacture and install is provided, that is constructed by vertical posts, which are connected to one another at intersecting points, and horizontally running cross-members such that rectangular mounting areas are provided for the individual PV modules. The posts and cross-members are formed in a material-saving manner by conventional profiles, and a division of the posts into two interconnectable sections substantially facilitates the assembly. An electrical connection is provided such that active surfaces which are arranged one above another can be operated at different electrical operating points and such that electrical lines are formed which are operated separately from one another and are arranged in a horizontally running manner.

Abstract: Provided is a method of manufacturing a high efficiency flexible thin film solar cell module including a see-thru pattern. The method of manufacturing a flexible thin film solar cell module includes: sequentially forming a light-absorbing layer, a first buffer layer, and a first transparent electrode layer on the release layer; forming a second buffer layer on the exposed bottom surface of the light-absorbing layer; forming a P2 scribing pattern by removing at least one portion of each of the first buffer layer, the light-absorbing layer, and the second buffer layer; forming a second transparent electrode layer on the second buffer layer and the first transparent electrode layer exposed by the P2 scribing pattern; and forming a P4 see-thru pattern by selectively removing at least one portion of the first buffer layer, the light-absorbing layer, the second buffer layer, and the second transparent electrode layer.

Abstract: Systems and methods taught herein provide thin film semiconductor devices such as thin film photovoltaic devices having via holes that enable electrical connection with a bottom surface of a topside contact of the thin film semiconductor device via the back side of the device (e.g., during mounting of the device). In some embodiments, the via holes are electrically insulated.

Abstract: The present invention provides a thermoelectric conversion material having a considerably increased Seebeck coefficient, and a thermoelectric conversion device, a thermo-electrochemical cell and a thermoelectric sensor which include the material. The thermoelectric conversion material of the present invention includes a redox pair and a capture compound which captures only one of the redox pair selectively at low temperature and releases at high temperature.

Abstract: Dye-sensitized ion-pumping membranes and methods of preparing said membranes are described herein. A regenerative and reversible photoactive dye is covalently-bonded to membrane or separator for ion-pumping. The photoactive dye-functionalized membranes can be arranged with other ion-exchange membranes, which serve as selective contacts to afford photovoltaic action and therefore form a power-producing membrane that pumps ions for use in driving an ion-exchange or ion-transport process, such as desalination and electrodialysis.

Abstract: A bifacial light-harvesting dye-sensitized solar cell is provided and has: a first transparent substrate, a second transparent substrate, a working electrode, a first semiconductor layer, a second semiconductor layer, a third semiconductor layer, a counter electrode, a light-transmitting catalyst layer, and a liquid electrolyte. A photoelectric conversion efficiency of the dye-sensitized solar cell is improved by using a specific working electrode structure.

Abstract: Disclosed herein are perovskite based optoelectronic devices made entirely via solution-processing at low temperatures (<150° C.) which provide for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices. These perovskite based optoelectronic devices are produced using an electron transport layer on which the perovskite layer is formed which is passivated using a ligand selected to reduce electron-hole recombination at the interface between the electron transport layer and the perovskite layer.

Abstract: The present application discloses compounds and compositions, useful in the manufacture of dye-sensitized solar cells and other similar technology.

Abstract: A method for fabricating thin-film optoelectronic devices (100), the method comprising: providing a alkali-nondiffusing substrate (110), forming a back-contact layer (120); forming at least one absorber layer (130) made of an ABC chalcogenide material, adding least one and advantageously at least two different alkali metals, and forming at least one front-contact layer (150) wherein one of said alkali metals comprise Rb and/or Cs and where, following forming said front-contact layer, in the interval of layers (470) from back-contact layer (120), exclusive, to front-contact layer (150), inclusive, the comprised amounts resulting from adding alkali metals are, for Rb and/or Cs, in the range of 500 to 10000 ppm and, for the other alkali metals, typically Na or K, in the range of 5 to 2000 ppm and at most ½ and at least 1/2000 of the comprised amount of Rb and/or Cs.

Abstract: The invention provides an optoelectronic device comprising a mixed-anion perovskite, wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions. The invention further provides a mixed-halide perovskite of the formula (I) [A][B][X]3 wherein: [A] is at least one organic cation; [B] is at least one divalent metal cation; and [X] is said two or more different halide anions. In another aspect, the invention provides the use of a mixed-anion perovskite as a sensitizer in an optoelectronic device, wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions. The invention also provides a photosensitizing material for an optoelectronic device comprising a mixed-anion perovskite wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions.

Abstract: A voltage converting device includes: a DC/DC converter configured to step down a voltage of a power supply and output the stepped-down voltage to a low-voltage power supply having a voltage lower than a voltage of the power supply; a control device configured to control the DC/DC converter; and a determining unit configured to determine whether a voltage of the power supply input to the DC/DC converter is within a predetermined voltage range, wherein the control device switches, on the basis of a determination result of the determining unit, between a first control in which the DC/DC converter is caused to perform a step-down operation and electric power is supplied to a load connected to the low-voltage power supply and a second control in which a step-down operation of the DC/DC converter stops and electric power is supplied from the low-voltage power supply to the load.

Abstract: A photovoltaic module includes at least one solar cell, an encapsulant encapsulating the at least one solar cell, a frontsheet juxtaposed with the encapsulant, and backsheet juxtaposed with the encapsulant. The frontsheet includes a glass layer, a polymer layer attached to the glass layer, and an adhesive layer attaching the polymer layer to the glass layer. The backsheet includes a single-layer, moisture-resistant, fire-retardant membrane.

Abstract: A semiconductor device having a highly doped quantum structure emitter is disclosed. In an embodiment, the semiconductor device includes a quantum structure emitter. The quantum structure emitter includes of a first layer made of an undoped semiconductor material with a large band gap, a second, middle, highly doped layer made of a semiconductor material with a low band gap and a third, undoped layer made of a semiconductor material with a large band gap.

Abstract: Provided a semiconductor light detection element including: a semiconductor portion having a front surface including a light reception region that receives incident light and photoelectrically converting the incident light incident on the light reception region; a metal portion provided on the front surface; and a carbon nanotube film provided on the light reception region and formed by depositing a plurality of carbon nanotubes. The carbon nanotube film extends over an upper surface of the metal portion from an upper surface of the light reception region.

Abstract: A microelectronic device includes: a photovoltaic module configured to convert a light energy into an electric energy; a converter configured to convert a voltage output from the photovoltaic module into a predetermined voltage; a capacitor configured to store an electric energy transferred from the converter; and a controller configured to predict an available current of a next time slot based on the electric energy stored in the capacitor, and determine a consumed current of a load system of the next time slot based on the predicted available current.

Abstract: Wires (22) electrically connecting solar cells (10) include first wires (22a) and second wires (22b). The first wires (22a) are connected to the first-conductivity-type electrodes (12) of a first one of the solar cells (10) and the second-conductivity-type electrodes (13) of a second one of the solar cells 10 that is adjacent to the first one of the solar cells (10). The second wires (22b) are connected to the second-conductivity-type electrodes (13) of the first one of the solar cells (10) and the first-conductivity-type electrodes (12) of the second one of the solar cells (10). The second wires (22b) are electrically separated by holes (21a) extending through both the second wires (22b) and an insulating base member (21).

Abstract: One embodiment can provide a photovoltaic roof module. The photovoltaic roof module can include a plurality of photovoltaic roof tiles positioned side by side. A respective solar roof tile comprises a plurality of photovoltaic structures positioned between a front cover and a back cover, and the photovoltaic structures are electrically coupled to each other in series. The photovoltaic roof tiles are electrically coupled to each other in parallel.

Abstract: A photovoltaic device includes an absorber layer having a back contact formed on the absorber layer, the back contact having an exposed surface free from a substrate. It further includes a top contact formed in contact with a transparent conductive layer opposite the back contact and a stressor layer forming a superstrate on the absorber layer opposite the back contact.

Abstract: A silicon solar cell with high photoelectric conversion efficiency is disclosed. A solar cell for converting light incident from an outside into electricity according to the present invention includes a substrate, a lower electrode, a ferroelectric layer, an auxiliary electrode, a first conductivity-type semiconductor layer, a second conductivity-type semiconductor layer, and an upper electrode. The lower electrode is formed on the substrate. The ferroelectric layer is formed on the substrate and outside the lower electrode. The auxiliary electrode is formed on the ferroelectric layer. The first conductivity-type semiconductor layer is formed on the lower electrode and the auxiliary electrode. The second conductivity-type semiconductor layer is formed on the first conductivity-type semiconductor layer, and is composed of a semiconductor of a second conductivity type opposite to a first conductivity type.

Abstract: The invention relates to a process for forming a conductive track or coating on a substrate, comprising: applying a conductive paste to the substrate, the conductive paste comprising a solids portion dispersed in an organic medium, the solids portion comprising particles of electrically conductive material and an inorganic particle mixture comprising substantially crystalline particles of two or more different metal compounds, wherein the inorganic particle mixture includes substantially crystalline particles of a tellurium compound and is substantially lead free; and firing the applied conductive paste on the surface of the substrate with a firing profile in which the temperature of the surface of the applied conductive paste exceeds 500° C. for a period of two minutes or less. The invention further relates to a substrate having a conductive track or coating formed thereon.

Abstract: A stacked multi-junction solar cell with a first subcell having a top and a bottom, and with a second subcell. The first subcell is implemented as the topmost subcell so that incident light first strikes the top of the first subcell and after that strikes the second subcell through the bottom. A first tunnel diode is arranged between the bottom of the first subcell and the second subcell. A window layer is arranged on the top of the first subcell, and the band gap of the window layer is larger than the band gap of the first subcell. A cover layer is arranged below metal fingers and above the window layer, and an additional layer is arranged below the cover layer and above the window layer. A thickness of the additional layer is less than the thickness of the window layer.

Abstract: A method of expanding a sheet includes the steps of gripping the sheet with a first gripping unit and a second griping unit and gripping the sheet with a third gripping unit and a fourth gripping unit, and expanding the sheet by moving the first gripping unit and the second griping unit away from each other in first directions relatively and moving the third gripping unit and the fourth gripping unit away from each other in second directions relatively. In the step of expanding the sheet, the states of the sheet that is under tension are detected, and movement of the first gripping unit, the second griping unit, the third gripping unit, and the fourth gripping unit is controlled based on the detected states of the sheet.

Abstract: Approaches for the metallization of solar cells and the resulting solar cells are described. In an example, a method of fabricating a solar cell involves forming a barrier layer on a semiconductor region disposed in or above a substrate. The semiconductor region includes monocrystalline or polycrystalline silicon. The method also involves forming a conductive paste layer on the barrier layer. The method also involves forming a conductive layer from the conductive paste layer. The method also involves forming a contact structure for the semiconductor region of the solar cell, the contact structure including at least the conductive layer.

Abstract: A backsheet for a photovoltaic module includes a support, an adhesive layer provided on one side of the support, and an outer layer provided on the other side of the support, characterized in that at least one of the adhesive layer and the outer layer is coated from an aqueous composition, and the aqueous composition includes a water soluble or dispersible binder and a water dispersible core/shell polyisocyanate.

Abstract: A method of producing a graphene film (22) includes forming a catalyst film (20) on a support (18); forming a graphene film (22) on the catalyst film (20); and electrolytically removing the catalyst film (20) from the support (18). The method may include transferring the graphene film (22) to a substrate (29). A supported graphene film includes a conductive support (18); a catalyst film (20) formed on the conductive support (18) having a thickness in a range of 1 nm to 10 ?m, and a graphene film (22) formed on the catalyst film (20).

Abstract: A photoelectric conversion element is provided. The photoelectric conversion element comprises a substrate, a first electrode, an electron transport layer, a hole transport layer, and a second electrode. The electron transport layer comprises a photosensitizing compound. The hole transport layer comprises a basic compound A and an ionic compound B. The basic compound A is represented by the following formula (1): where each of R1 and R2 independently represents an alkyl group or an aromatic hydrocarbon group, or R1 and R2 share bond connectivity to form a nitrogen-containing heterocyclic ring; and the ionic compound B is represented by the following formula (2): where X+ represents a counter cation.

Abstract: An OLED is disclosed that includes an enhancement layer having optically active metamaterials, or hyperbolic metamaterials, which transfer radiative energy from the organic emissive material to a non-radiative mode, wherein the enhancement layer is disposed over the organic emissive layer opposite from the first electrode, and is positioned no more than a threshold distance away from the organic emissive layer, wherein the organic emissive material has a total non-radiative decay rate constant and a total radiative decay rate constant due to the presence of the enhancement layer, and the threshold distance is where the total non-radiative decay rate constant is equal to the total radiative decay rate constant; and an outcoupling layer disposed over the enhancement layer, wherein the outcoupling layer scatters radiative energy from the enhancement layer to free space.

Abstract: The invention provides an optoelectronic device comprising a mixed-anion perovskite, wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions. The invention further provides a mixed halide perovskite of the formula (I) [A][B][X]3 wherein: [A] is at least one organic cation; [B] is at least one divalent metal cation; and [X] is said two or more different halide anions. In another aspect, the invention provides the use of a mixed-anion perovskite as a sensitizer in an optoelectronic device, wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions. The invention also provides a photosensitizing material for an optoelectronic device comprising a mixed-anion perovskite wherein the mixed-anion perovskite comprises two or more different anions selected from halide anions and chalcogenide anions.

Abstract: Photovoltaic devices such as solar cells, hybrid solar cell-batteries, and other such devices may include an active layer disposed between two electrodes, the active layer having perovskite material and other material such as mesoporous material, interfacial layers, thin-coat interfacial layers, and combinations thereof. The perovskite material may be photoactive. The perovskite material may be disposed between two or more other materials in the photovoltaic device. Inclusion of these materials in various arrangements within an active layer of a photovoltaic device may improve device performance. Other materials may be included to further improve device performance, such as, for example: additional perovskites, and additional interfacial layers.

Abstract: Systems and methods are described herein to grow a layered structure. The layered structure comprises a first germanium substrate layer having a first lattice constant, a second layer that has a second lattice constant and is epitaxially grown over the first germanium substrate layer, wherein the second layer has a composite of a first constituent and a second constituent, and has a first ratio between the first constituent and the second constituent, and a third layer that has a third lattice constant and is epitaxially grown over the second layer, wherein the third layer has a composite of a third constituent and a fourth constituent, and has a second ratio between the third constituent and the fourth constituent, wherein the first ratio and the second ratio are selected such that the first lattice constant is between the second lattice constant and the third lattice constant.