Abstract: Provided is a semiconductor device of normally-off operation type having a low on-resistance. An epitaxial substrate for it includes: a base substrate; a channel layer made of a first group-III nitride having a composition of Inx1Aly1Gaz1N at least containing Al and Ga and x1=0 and 0?y1?0.3; and a barrier layer made of a second group-III nitride having a composition of Inx2Aly2Gaz2N at least containing In and Al. The composition of the second group-III nitride is, in a ternary phase diagram for InN, AlN, and GaN, in a certain range that is determined in accordance with the composition of the first group-III nitride. The barrier layer has a thickness of 3 nm or less. A low-crystallinity insulating layer is further formed on the barrier layer. The low-crystallinity insulating layer is made of silicon nitride and has a thickness of 3 nm or less.

Abstract: Fabrication methods of a high frequency (sub-micron gate length) operation of AlInGaN/InGaN/GaN MOS-DHFET, and the HFET device resulting from the fabrication methods, are generally disclosed. The method of forming the HFET device generally includes a novel double-recess etching and a pulsed deposition of an ultra-thin, high-quality silicon dioxide layer as the active gate-insulator. The methods of the present invention can be utilized to form any suitable field effect transistor (FET), and are particular suited for forming high electron mobility transistors (HEMT).

Abstract: A HEMT includes a silicon substrate, an unintentionally doped gallium nitride (UID GaN) layer over the silicon substrate, a donor-supply layer over the UID GaN layer, a gate structure, a drain, and a source over the donor-supply layer, and a passivation material layer having one or more buried portions contacting or almost contacting the UID GaN layer. A carrier channel layer at the interface of the donor-supply layer and the UID GaN layer has patches of non-conduction in a drift region between the gate and the drain. A method for making the HEMT is also provided.

Abstract: High electron mobility transistors and fabrication processes are presented in which a barrier material layer of uniform thickness is provided for threshold voltage control under an enhanced channel charge inducing material layer (ECCIML) in source and drain regions with the ECCIML layer removed in the gate region.

Abstract: A monolithically integrated device includes a substrate, a first set of Group III nitride epitaxial layers grown for a first HFET on a first region of the substrate, and a second set of Group III nitride epitaxial layers for a second HFET grown on a second region of the substrate.

Abstract: A semiconductor device including a first GaN layer, an AlGaN layer, a second GaN layer, a gate electrode, a source electrode, and a drain electrode sequentially stacked on a substrate, capable of improving a leakage current and a breakdown voltage characteristics generated in the gate electrode by locally forming a p type GaN layer on the AlGaN layer, and a manufacturing method thereof, and a manufacturing method thereof are provided. The semiconductor device includes: a substrate, a first GaN layer formed on the substrate, an AlGaN layer formed on the first GaN layer, a second GaN layer formed on the AlGaN layer and including a p type GaN layer, and a gate electrode formed on the second GaN layer, wherein the p type GaN layer may be in contact with a portion of the gate electrode.

Abstract: A semiconductor device such as a diode or transistor includes a semiconductor substrate, a first region of III-V semiconductor material on the semiconductor substrate and a second region of III-V semiconductor material on the first region. The second region is spaced apart from the semiconductor substrate by the first region. The second region is of a different composition than the first region. The semiconductor device further includes a buried contact extending from the semiconductor substrate to the second region through the first region. The buried contact electrically connects the second region to the semiconductor substrate.

Abstract: A gated III-V semiconductor structure and a method for fabricating the gated III-V semiconductor structure includes a threshold modifying dopant region within a III-V semiconductor barrier layer at the base of an aperture through a passivation layer that otherwise passivates the III-V semiconductor barrier layer. The passivation layer, which may comprise an aluminum-silicon nitride material, has particular bandgap and permittivity properties that provide for enhanced performance of a III-V semiconductor device that derives from the III-V semiconductor structure absent a field plate. The threshold modifying dopant region provides the possibility for forming both an enhancement mode gated III-V semiconductor structure and a depletion mode III-V semiconductor structure on the same substrate.

Abstract: Enhancement mode III-nitride HEMT and method for manufacturing an enhancement mode III-nitride HEMT are disclosed. In one aspect, the method includes providing a substrate having a stack of layers on the substrate, each layer including a III-nitride material, and a passivation layer having high temperature silicon nitride overlying and in contact with an upper layer of the stack of III-nitride layers, wherein the HT silicon nitride is formed by MOCVD or LPCVD or any equivalent technique at a temperature higher than about 450° C. The method also includes forming a recessed gate region by removing the passivation layer only in the gate region, thereby exposing the underlying upper layer. The method also includes forming a p-doped GaN layer at least in the recessed gate region, thereby filling at least partially the recessed gate region, and forming a gate contact and source/drain contacts.

Abstract: A semiconductor device includes: a buffer layer provided on a substrate and made of a group III-V nitride semiconductor; a first semiconductor layer provided on the buffer layer and made of a group III-V nitride semiconductor; a second semiconductor layer provided on the first semiconductor layer and made of a group III-V nitride semiconductor; a back electrode provided on a back surface of the substrate and connected to a ground; a source electrode and a drain electrode provided on the second semiconductor layer so as to be apart from each other; a gate electrode provided on the second semiconductor layer; and a plug which passes through the second semiconductor layer, the first semiconductor layer, and the buffer layer, and reaches at least the substrate to electrically connect the source electrode and the back electrode.

Abstract: Methods and apparatuses are disclosed for providing heterostructure field effect transistors (HFETs) with high-quality gate dielectric and field plate dielectric. The gate dielectric and field plate dielectric are in situ deposited on a semiconductor surface. The location of the gate electrode may be defined by etching a first pattern in the field plate dielectric and using the gate dielectric as an etch-stop. Alternatively, an additional etch-stop layer may be in situ deposited between the gate dielectric and the field plate dielectric. After etching the first pattern, a conductive material may be deposited and patterned to define the gate electrode. Source and drain electrodes that electrically contact the semiconductor surface are formed on opposite sides of the gate electrode.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; a nitride compound semiconductor stacked structure formed on or above the substrate; and a gate electrode, a source electrode and a drain electrode formed on or above the compound semiconductor stacked structure. A recess positioning between the gate electrode and the drain electrode in a plan view is formed at a surface of the compound semiconductor stacked structure.

Abstract: Disclosed are a semiconductor device including a stepped gate electrode and a method of fabricating the semiconductor device. The semiconductor device according to an exemplary embodiment of the present disclosure includes: a semiconductor substrate having a structure including a plurality of epitaxial layers and including an under-cut region formed in a part of a Schottky layer in an upper most part thereof; a cap layer, a first nitride layer and a second nitride layer sequentially formed on the semiconductor substrate to form a stepped gate insulating layer pattern; and a stepped gate electrode formed by depositing a heat-resistant metal through the gate insulating layer pattern, wherein the under-cut region includes an air-cavity formed between the gate electrode and the Schottky layer.

Abstract: A hetero-structure field effect transistor (HFET). The HFET may include a first contact and a second contact and a hetero-junction structure. The hetero-junction structure may include a first layer made from a first semiconductor material and a second layer made from a second semiconductor material. An interface at which the first layer and the second layer are in contact with each other may be provided, along which a two dimensional electron gas (2DEG) is formed in a part of the first layer directly adjacent to the interface, for propagating of electrical signals from the first contact to the second contact or vice versa. The transistor may further include a gate structure for controlling a conductance of the channel; a substrate layer made from a substrate semiconductor material, and a dielectric layer separating the first layer from the substrate layer. The second contact may include an electrical connection between the substrate layer and the first layer.

Abstract: A method of manufacturing a nitride semiconductor device including: forming a nitride semiconductor layer over a substrate wherein the nitride semiconductor layer has a 2DEG channel inside; forming a drain electrode in ohmic contact with the nitride semiconductor layer and a source electrode spaced apart from the drain electrode, in Schottky contact with the nitride semiconductor layer, wherein the source electrode has an ohmic pattern in ohmic contact with the nitride semiconductor layer inside; forming a dielectric layer on the nitride semiconductor layer between the drain electrode and the source electrode and on at least a portion of the source electrode; and forming a gate electrode on the dielectric layer to be spaced apart from the drain electrode, wherein a portion of the gate electrode is formed on the dielectric layer over a drain-side edge portion of the source electrode.

Abstract: A high electron mobility transistor (HEMT) includes a silicon substrate, an unintentionally doped gallium nitride (UID GaN) layer over the silicon substrate. The HEMT further includes a donor-supply layer over the UID GaN layer, a gate structure, a drain, and a source over the donor-supply layer. The HEMT further includes a dielectric layer having one or more dielectric plug portions in the donor-supply layer and top portions between the gate structure and the drain over the donor-supply layer. A method for making the HEMT is also provided.

Abstract: A method of making a high-electron mobility transistor (HEMT) includes forming an unintentionally doped gallium nitride (UID GaN) layer over a silicon substrate, a donor-supply layer over the UID GaN layer, a gate, a passivation layer over the gate and portions of the donor-supply layer, an ohmic source structure and an ohmic drain structure over the donor-supply layer and portions of the passivation layer. The source structure includes a source contact portion and an overhead portion. The overhead portion overlaps the passivation layer between the source contact portion and the gate, and may overlap a portion of the gate and a portion of the passivation layer between the gate and the drain structure.

Abstract: A method for manufacturing a transistor assembly includes the steps of: (a) forming a transistor; (b) polishing a base substrate; and (c) securing the transistor of which the base substrate is polished to a support substrate. The step (a) is a step of forming a first semiconductor layer and a second semiconductor layer on a principle surface of the base substrate. The step (b) is a step of polishing a surface of the base substrate opposite to the principle surface. The step (c) is a step of securing the transistor on the support substrate in the presence of a stress applied on the base substrate in such a direction that a warp of the base substrate is reduced. The base substrate is made of a material different from that of the first semiconductor layer and the second semiconductor layer, and a tensile stress is applied on the second semiconductor layer.

Abstract: Methods and systems for fabricating an integrated BiFET using two separate growth procedures are disclosed. Performance of the method fabricates the FET portion of the BiFET in a first fabrication environment. Performance of the method fabricates the HBT portion of the BiFET in a second fabrication environment. By separating the fabrication of the FET portion and the HBT portion in two or more separate reactors, the optimum device performance can be achieved for both devices.

Abstract: An enhancement-mode group III-N high electron mobility transistor (HEMT) with a reverse polarization cap is formed in a method that utilizes a reverse polarization cap structure, such as an InGaN cap structure, to deplete the two-dimensional electron gas (2DEG) and form a normally off device, and a spacer layer that lies below the reverse polarization cap structure and above the barrier layer of the HEMT which allows the reverse polarization cap layer to be etched without etching into the barrier layer.

Abstract: Disclosed herein is a nitride based semiconductor device. There is provided a nitride based semiconductor device including: a base substrate; an epitaxial growth layer disposed on the base substrate and generating 2-dimensional electron gas (2DEG) therein; and an electrode structure disposed on the epitaxial growth layer and having an extension extending into the epitaxial growth layer, wherein the epitaxial growth layer includes a depressing part depressed thereinto from the surface of the epitaxial growth layer, and the depressing part includes: a first area in which the extension is disposed; and a second area that is an area other than the first area.

Abstract: Methods and apparatuses for forming a device structure including a high-thermal-conductivity substrate are disclosed herein. A method forming such a device structure may comprise forming an active layer over a first substrate in a manner such that a frontside of the active layer faces the first substrate and a backside of the active layer faces away from the first substrate, forming a second substrate over the backside of the active layer, and removing the first substrate to expose the frontside of the active layer. Other embodiments are described and claimed.

Abstract: The present disclosure relates to an enhancement mode gallium nitride (GaN) transistor device. The GaN transistor device has an electron supply layer located on top of a GaN layer. An etch stop layer (e.g., AlN) is disposed above the electron supply layer. A gate structure is formed on top of the etch stop layer, such that the bottom surface of the gate structure is located vertically above the etch stop layer. The position of etch stop layer in the GaN transistor device stack allows it to both enhance gate definition during processing (e.g., selective etching of the gate structure located on top of the AlN layer) and to act as a gate insulator that reduces gate leakage of the GaN transistor device.

Abstract: A semiconductor structure includes a first III-V compound layer. A second III-V compound layer is disposed on the first III-V compound layer and is different from the first III-V compound layer in composition. A carrier channel is located between the first III-V compound layer and the second III-V compound layer. A source feature and a drain feature are disposed on the second III-V compound layer. A gate electrode is disposed over the second III-V compound layer between the source feature and the drain feature. A fluorine region is embedded in the second III-V compound layer under the gate electrode. A gate dielectric layer is disposed over the second III-V compound layer. The gate dielectric layer has a fluorine segment on the fluorine region and under at least a portion of the gate electrode.

Abstract: An electrode structure, a GaN-based semiconductor device including the electrode structure, and methods of manufacturing the same, may include a GaN-based semiconductor layer and an electrode structure on the GaN-based semiconductor layer. The electrode structure may include an electrode element including a conductive material and a diffusion layer between the electrode element and the GaN-based semiconductor layer. The diffusion layer may include a material which is an n-type dopant with respect to the GaN-based semiconductor layer, and the diffusion layer may contact the GaN-based semiconductor layer. A region of the GaN-based semiconductor layer contacting the diffusion layer may be doped with the n-type dopant. The material of the diffusion layer may comprise a Group 4 element.

Abstract: The disclosure relates to electronic devices and associated methods of manufacture including materials of the Group III/N. An exemplary device successively includes, from its base towards its surface: (i) a support substrate, (ii) a layer adapted to contain an electron gas, (iii) a barrier layer, and (iv) a superficial layer extending on at least one part of the surface of the barrier layer, wherein the superficial layer has an electrical field of which the current is controlled so that, in at least one first region of the superficial layer, the electrical field is weaker than in a second region of the superficial layer.

Abstract: Embodiments of the present disclosure describe apparatuses, methods, and systems of an integrated circuit (IC) device such as, for example, a high electron mobility transistor (HEMT) or metal-insulator-semiconductor field-effect transistor (MISFET), or combinations thereof. The IC device includes a buffer layer formed on a substrate, a barrier layer formed on the buffer layer, the barrier layer including aluminum (Al), nitrogen (N), and at least one of indium (In) and gallium (Ga), a cap layer formed on the barrier layer, the cap layer including nitrogen (N) and at least one of indium (In) and gallium (Ga), and a gate formed on the cap layer, the gate being directly coupled with the cap layer. Other embodiments may also be described and/or claimed.

Abstract: Structures, devices and methods are provided for creating heterojunction AlGaN/GaN metal two-dimensional electron gas (2DEG) tunnel-junction field-effect transistors (TJ-FET). In one aspect, metal-2DEG Schottky tunnel junctions can be employed in group III-Nitride field-effect devices that enable normally-off operation, large breakdown voltage, low leakage current, and high on/off current ratio. As a further advantage, AlGaN/GaN metal-2DEG TJ-FETs are disclosed that can be fabricated in a lateral configuration and/or a vertical configuration. Further non-limiting embodiments are provided that illustrate the advantages and flexibility of the disclosed structures.

Abstract: An integrated device including a III-nitride HEMT and a Schottky diode includes a substrate comprising a first III-nitride material and a drift region comprising a second III-nitride material coupled to the substrate and disposed adjacent to the substrate along a vertical direction. The integrated device also includes a first barrier layer coupled to the drift region and a channel layer comprising a third III-nitride material having a first bandgap and coupled to the barrier layer. The integrated device further includes a second barrier layer characterized by a second bandgap and coupled to the channel layer and a Schottky contact coupled to the drift region. The second bandgap is greater than the first bandgap.

Abstract: A semiconductor structure includes a first III-V compound layer. A second III-V compound layer is disposed on the first III-V compound layer and different from the first III-V compound layer in composition. A carrier channel is located between the first III-V compound layer and the second III-V compound layer. A source feature and a drain feature are disposed on the second III-V compound layer. A gate electrode is disposed over the second III-V compound layer between the source feature and the drain feature. A carrier channel depleting layer is disposed on the second III-V compound layer. The carrier channel depleting layer is deposited using plasma and a portion of the carrier channel depleting layer is under at least a portion of the gate electrode.

Abstract: A semiconductor device includes a first element structure that includes a charge supply layer of first polarity; a charge channel layer of second polarity, the charge channel layer being formed above the charge supply layer and including a recess portion; and a first electrode formed in the recess portion above the charge channel layer.

Abstract: The present invention relates to a nitride semiconductor device and a manufacturing method thereof. According to one aspect of the present invention, a nitride semiconductor device including: a nitride semiconductor layer having a 2DEG channel; a source electrode in ohmic contact with the nitride semiconductor layer; a drain electrode in ohmic contact with the nitride semiconductor layer; a plurality of p-type nitride semiconductor segments formed on the nitride semiconductor layer and each formed lengthways from a first sidewall thereof, which is spaced apart from the source electrode, to a drain side; and a gate electrode formed to be close to the source electrode and in contact with the nitride semiconductor layer between the plurality of p-type semiconductor segments and portions of the p-type semiconductor segments extending in the direction of a source-side sidewall of the gate electrode aligned with the first sidewalls of the p-type nitride semiconductor segments is provided.

Abstract: The present invention relates to a nitride semiconductor device and a manufacturing method thereof. According to one aspect of the present invention, a nitride semiconductor device including: a nitride semiconductor layer having a 2DEG channel; a source electrode in ohmic contact with the nitride semiconductor layer; a drain electrode in ohmic contact with the nitride semiconductor layer; a p-type nitride layer formed on the nitride semiconductor layer between the source and drain electrodes; an n-type nitride layer formed on the p-type nitride layer; and a gate electrode formed between the source and drain electrodes to be close to the source electrode and in contact with the n-type nitride layer so that a source-side sidewall thereof is aligned with source-side sidewalls of the p-type and n-type nitride layers is provided. Further, a method of manufacturing a nitride semiconductor device is provided.

Abstract: An improved structure of the high electron mobility transistor (HEMT) and a fabrication method thereof are disclosed. The improved HEMT structure comprises a substrate, a channel layer, a spacing layer, a carrier supply layer, a Schottky layer, a first etch stop layer, a first n type doped layer formed by AlxGa1-xAs, and a second n type doped layer. The fabrication method comprises steps of: etching a gate, a drain, and a source recess by using a multiple selective etching process. Below the gate, the drain, and the source recess is the Schottky layer. A gate electrode is deposited in the gate recess to form Schottky contact. A drain electrode and a source electrode are deposited to form ohmic contacts in the drain recess and the source recess respectively, and on the second n type doped layer surrounding the drain recess and the source recess respectively.

Abstract: Provided is an epitaxial substrate capable of achieving a semiconductor device that has excellent schottky contact characteristics as well as satisfactory device characteristics. On a base substrate, a channel layer formed of a first group III nitride that contains at least Al and Ga and has a composition of Inx1Aly1Gaz1N (x1+y1+z1=1) is formed. On the channel layer, a barrier layer formed of a second group III nitride that contains at least In and Al and has a composition of Inx2Aly2Gaz2N (x2+y2+z2=1) is formed such that an In composition ratio of a near-surface portion is smaller than an In composition ratio of a portion other than the near-surface portion.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; an electron channel layer and an electron supply layer formed over the substrate; a gate electrode, a source electrode and a drain electrode formed on or above the electron supply layer; and a p-type semiconductor layer formed between the electron supply layer and the gate electrode. The p-type semiconductor layer contains, as a p-type impurity, an element same as that being contained in at least either of the electron channel layer and the electron supply layer.

Abstract: A semiconductor device includes a first semiconductor layer formed on a substrate, the first semiconductor containing an impurity element; a second semiconductor layer formed on the first semiconductor layer; a third semiconductor layer formed on the second semiconductor layer; and a gate electrode, a source electrode and a drain electrode that are formed on the third semiconductor layer. In the semiconductor device, the second semiconductor layer includes an impurity diffusion region in which an impurity element contained in the first semiconductor layer is diffused, the impurity diffusion region being located directly beneath the gate electrode and being in contact with the first semiconductor layer, and the impurity element causes the impurity diffusion region to be a p-type impurity diffusion region.

Abstract: A method for fabricating a semiconductor device is disclosed. The method includes sequentially forming a first semiconductor layer, a second semiconductor layer and a semiconductor cap layer containing a p-type impurity element on a substrate, forming a dielectric layer having an opening after the forming of the semiconductor cap layer, forming a third semiconductor layer containing a p-type impurity element on the semiconductor cap layer exposed from the opening of the dielectric layer, and forming a gate electrode on the third semiconductor layer.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; a compound semiconductor stacked structure formed over the substrate; and an amorphous insulating film formed between the substrate and the compound semiconductor stacked structure.

Abstract: A semiconductor including a lateral HEMT and to a method for production of a lateral HEMT is disclosed. In one embodiment, the lateral HEMT has a substrate and a first layer, wherein the first layer has a semiconductor material of a first conduction type and is arranged at least partially on the substrate. Furthermore, the lateral HEMT has a second layer, wherein the second layer has a semiconductor material and is arranged at least partially on the first layer. In addition, the lateral HEMT has a third layer, wherein the third layer has a semiconductor material of a second conduction type, which is complementary to the first conduction type, and is arranged at least partially in the first layer.

Abstract: A semiconductor device includes: a first semiconductor layer formed on a substrate; a second semiconductor layer formed on the first semiconductor layer; a third semiconductor layer formed on the second semiconductor layer; a gate electrode formed on the third semiconductor layer; and a source electrode and a drain electrode formed in contact with the second semiconductor layer, wherein a semiconductor material of the third semiconductor layer is doped with a p-type impurity element; and the third semiconductor layer has a jutting out region that juts out beyond an edge of the gate electrode toward a side where the drain electrode is provided.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; a compound semiconductor stacked structure formed over the substrate; and a gate electrode, a source electrode and a drain electrode formed on or above the compound semiconductor stacked structure. The compound semiconductor stacked structure includes: an electron channel layer; and a nitride semiconductor layer which includes an electron supply layer formed over the electron channel layer. An indium (In) fraction at a surface of the nitride semiconductor layer in each of a region between the gate electrode and the source electrode and a region between the gate electrode and the drain electrode is lower than an indium (In) fraction at a surface of the nitride semiconductor layer in a region below the gate electrode.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; an electron channel layer and an electron supply layer formed over the substrate; a gate electrode, a source electrode and a drain electrode formed on or above the electron supply layer; a first p-type semiconductor layer formed between the electron supply layer and the gate electrode; and a second p-type semiconductor layer formed between the electron supply layer and at least one of the source electrode and the drain electrode. The one of the source electrode and the drain electrode on the second p-type semiconductor layer includes: a first metal film; and a second metal film Which contacts the first metal film on the gate electrode side of the first metal film, and a resistance of which is higher than that of the first metal film.

Abstract: An embodiment of a compound semiconductor device includes: a substrate; an electron channel layer and an electron supply layer formed over the substrate; a gate electrode, a source electrode and a drain electrode formed on or above the electron supply layer; a p-type semiconductor layer formed between the electron supply layer and the gate electrode; and a hole barrier layer formed between the electron supply layer and the p-type semiconductor layer, a band gap of the hole barrier layer being larger than that of the electron supply layer.

Abstract: An enhancement-mode GaN transistor and a method of forming it. The enhancement-mode GaN transistor includes a substrate, transition layers, a buffer layer comprised of a III Nitride material, a barrier layer comprised of a III Nitride material, drain and source contacts, a gate III-V compound containing acceptor type dopant elements, and a gate metal, where the gate III-V compound and the gate metal are formed with a single photo mask process to be self-aligned and the bottom of the gate metal and the top of the gate compound have the same dimension. The enhancement mode GaN transistor may also have a field plate made of Ohmic metal, where a drain Ohmic metal, a source Ohmic metal, and the field plate are formed by a single photo mask process.

Abstract: According to an example embodiment, a power device includes a substrate, a nitride-containing stack on the substrate, and an electric field dispersion unit. Source, drain, and gate electrodes are on the nitride-containing stack. The nitride-containing stack includes a first region that is configured to generate a larger electric field than that of a second region of the nitride-containing stack. The electric field dispersion unit may be between the substrate and the first region of the nitride-containing stack.

Abstract: An embodiment of a compound semiconductor device includes: a Si substrate; a Si oxide layer formed over a surface of the Si substrate; a nucleation layer formed over the Si oxide layer, the nucleation layer exposing a part of the Si oxide layer; and a compound semiconductor stacked structure formed over the Si oxide layer and the nucleation layer.

Abstract: Provided is a nitride semiconductor device comprising a base substrate; a buffer layer formed above the base substrate; an active layer formed on the buffer layer; and at least two electrodes formed above the active layer. The buffer layer includes one or more composite layers that each have a plurality of nitride semiconductor layers with different lattice constants, and at least one of the one or more composite layers is doped with carbon atoms and oxygen atoms in at least a portion of a carrier region of the nitride semiconductor having the largest lattice constant among the plurality of nitride semiconductor layers, the carrier region being a region in which carriers are generated due to the difference in lattice constants between this nitride semiconductor layer and the nitride semiconductor layer formed directly thereon.

Abstract: Embodiments of the present disclosure includes a III-N device having a substrate layer, a first III-N material layer on one side of the substrate layer, a second III-N material layer on the first III-N material layer, and a barrier layer disposed on another side of the substrate layer, the barrier layer being less electrically conductive than the substrate layer.

Abstract: A compound semiconductor device includes a substrate; and a compound semiconductor layer disposed over the substrate, wherein the compound semiconductor layer includes a first region having first conductivity-type carriers generated by activating a first impurity and also includes a second region having carriers at lower concentration as compared to the first region, the carriers being generated by activating a second impurity which is the same type as the first impurity.