Abstract: A III-nitride heterojunction power semiconductor device having a barrier layer that includes a region of reduced nitrogen content.

Abstract: The present invention has as an object to provide a FET having low on-resistance. The FET according to the present invention includes: first nitride semiconductor layer; a second nitride semiconductor layer formed on the first nitride semiconductor layer and having a higher band gap energy than the first nitride semiconductor layer; a third nitride semiconductor layer formed on the second nitride semiconductor layer; a fourth nitride semiconductor layer formed on the third nitride semiconductor layer and having a higher band gap energy than the third nitride semiconductor layer. A channel is formed in a heterojunction interface between the first nitride semiconductor layer and the second nitride semiconductor layer.

Abstract: A method for forming a low defect density heterojunction between a first and a second compound, the first and second compounds each includes a group III element combined with a group V element in the periodic table, the method includes the steps of introducing in the deposition chamber the flux of the group III element for the first compound at substantially the same time while introducing in the deposition chamber a flux of the group V element for the second compound, stopping the flux of the group III element for the first compound after a first predetermined time period, stopping the flux of the group V element for the first compound after a second predetermined time period, and introducing in the deposition chamber a flux of the group III element the group V element for the second compound.

Abstract: A high electron mobility transistor includes a free-standing supporting base having a III nitride region, a first III nitride barrier layer which is provided on the first III nitride barrier layer, a III nitride channel layer which is provided on the first III nitride barrier layer and forms a first heterojunction with the first III nitride barrier layer, a gate electrode provided on the III nitride channel layer so as to exert an electric field on the first heterojunction, a source electrode on the III nitride channel layer and the first III nitride barrier, and a drain electrode on the III nitride channel layer and the first III nitride barrier. The III nitride channel layer has compressive internal strain, and the piezoelectric field of the III nitride channel layer is oriented in the direction from the supporting base towards the first III nitride barrier layer.

Abstract: A semiconductor device according to the present invention including: a substrate; a compound semiconductor layer formed on the substrate; an element forming area provided in the compound semiconductor layer; and at least one semiconductor element, which includes a first main electrode and a main second electrode, wherein the at least one semiconductor element is formed in the element forming area, wherein the compound semiconductor layer includes: a first compound growth layer, which is formed on the substrate and includes the element forming area; and a second compound growth layer formed on the substrate to surround the element forming area when viewed from a plane, wherein the second compound growth layer has a crystallinity lower than a crystallinity of the first compound growth layer

Abstract: A uni-terminal transistor device is described. In one embodiment, an n-channel transistor comprises a first semiconductor layer having a discrete hole level H0; a second semiconductor layer having a conduction band minimum EC2; a wide bandgap semiconductor barrier layer disposed between the first and the second semiconductor layers; a gate dielectric layer disposed above the first semiconductor layer; and a gate metal layer disposed above the gate dielectric layer and having an effective workfunction selected to position the discrete hole level H0 below the conduction band minimum Ec2 for zero bias applied to the gate metal layer and to obtain n-terminal characteristics.

Abstract: An n-type GaN layer (3), a GaN layer (7) formed over the n-type GaN layer (3), an n-type AlGaN layer (9) formed over the GaN layer (7), a gate electrode (15) and a source electrode (13) formed over the n-type AlGaN layer (9), a drain electrode (14) formed below the n-type GaN layer (3), and a p-type GaN layer (4) formed between the GaN layer (7) and the drain electrode (14) are provided.

Abstract: A method of forming a semiconductor device, the method comprising providing a semiconductor layer, and providing a first layer of a first metal on the semiconductor layer. A second layer may be provided on the first layer of the first metal. The second layer may include a layer of silicon and a layer of a second metal, and the first and second metals may be different. The first metal may be titanium and the second metal may be nickel. Related devices, structures, and other methods are also discussed.

Abstract: A semiconductor device in provided having a substrate and a semiconductor layer formed on a main surface of the substrate. A plurality of first island electrodes and a plurality of second island electrodes are placed over the semiconductor layer. The plurality of first island electrodes and second island electrodes are spaced apart from each other so as to be alternatively arranged to produce two-dimensional active regions in all feasible areas of the semiconductor layer. Each side of the first island electrodes is opposite a side of the second island electrodes. The semiconductor device can also include a plurality of strip electrodes that are formed in the regions between the first island electrodes and the second island electrodes. The strip electrodes serve as the gate electrodes of a multi-island transistor. The first island electrodes serve as the source electrodes of the multi-island transistor. The second island electrodes serve as the drain electrodes of the multi-island transistor.

Abstract: The disclosure relates to a zero-bias heterojunction diode detector with varying impedance. The detector includes a substrate supporting a Schottky structure and an Ohmic contact layer. A metallic contact layer is formed over the Ohmic layer. The Schottky structure comprises a plurality of barrier layers and each of the plurality of barriers layers includes a first material and a second material. In one embodiment, the composition percentage of the second material in each of the barrier layers increases among the plurality of barrier layers from the substrate to the metal layer in order to provide a graded periodicity for the Schottky structure.

Abstract: A semiconductor device according to the embodiment includes a growth substrate; a first buffer layer having a compositional formula of RexSiy (0?x?2, 0?y?2) over the growth substrate; and a group III nitride-based epitaxial semiconductor layer having a compositional formula of InxAlyGa1-x-yN (0?x, 0?y, x+y?1) over the first buffer layer.

Abstract: A high electron mobility transistor (HEMT) is disclosed capable of performing as a pressure sensor. In one embodiment, the subject pressure sensor can be used for the detection of body fluid pressure. A piezoelectric, biocompatible film can be used to provide a pressure sensing functionalized gate surface for the HEMT. Embodiments of the disclosed sensor can be integrated with a wireless transmitter for constant pressure monitoring.

Abstract: A field-effect transistor provided with a channel layer, a carrier supply layer forming a heterojunction with the channel layer, a recessed portion recessed from a surface of the carrier supply layer, a first insulating layer formed at least along the recessed portion, a first gate electrode formed on the first insulating layer, a source electrode formed on one side of the recessed portion in a channel lengthwise direction, and a drain electrode formed on an opposite side of the recessed portion in the channel lengthwise direction. The recessed portion snakes in a direction intersecting the channel lengthwise direction, in the range of a channel length between the source electrode and the drain electrode.

Abstract: The present invention relates to a support for the epitaxy of a layer of a material of composition AlxInyGa(1-x-y)N, where 0?x?1, 0?y?1 and x+y?1, having successively from its base to its surface; a support substrate, a bonding layer, a monocrystalline seed layer for the epitaxial growth of the layer of material AlxInyGa(1-x-y)N. The support substrate is made of a material that presents an electrical resistivity of less than 10?3 ohm·cm and a thermal conductivity of greater than 100 W·m?1·K?1. The seed layer is in a material of the composition AlxInyGa(1-x-y)N, where 0?x?1, 0?y?1 and x+y?1. The seed and bonding layers provide a specific contact resistance that is less than or equal to 0.1 ohm·cm?2, and the materials of the support substrate, the bonding layer and the seed layer are refractory at a temperature of greater than 750° C. or even greater than 1000° C. The invention also relates to methods for manufacturing the support.

Abstract: Enhancement mode III-nitride devices are described. The 2DEG is depleted in the gate region so that the device is unable to conduct current when no bias is applied at the gate. Both gallium face and nitride face devices formed as enhancement mode devices.

Abstract: A nitride semiconductor device includes: a substrate; a first nitride semiconductor layer formed over the substrate; a second nitride semiconductor layer formed on the first nitride semiconductor layer and having a larger band gap energy than the first nitride semiconductor layer; a third nitride semiconductor layer formed on the second nitride semiconductor layer and including a p-type nitride semiconductor with at least a single-layer structure; a gate electrode formed on the third nitride semiconductor layer; and a source electrode and a drain electrode formed in regions located on both sides of the gate electrode, respectively. The third nitride semiconductor layer has a thickness greater in a portion below the gate electrode than in a portion below the side of the gate electrode.

Abstract: In one embodiment a lateral HEMT has a first layer, the first layer including a semiconducting material, and a second layer, the second layer including a semiconducting material and being at least partially arranged on the first layer. The lateral HEMT further has a passivation layer and a drift region, the drift region including a lateral width wd. The lateral HEMT further has at least one field plate, the at least one field plate being arranged at least partially on the passivation layer in a region of the drift region and including a lateral width wf, wherein wf<wd.

Abstract: The present invention is related to a method for manufacturing a low defect interface between a dielectric material and an III-V compound. More specifically, the present invention relates to a method for manufacturing a passivated interface between a dielectric material and an III-V compound. The present invention is also directed to a device comprising a low defect interface between a dielectric material and an III-V compound that has improved performance.

Abstract: The invention concerns a method for preparing a NIII-V semiconductor. According to the invention, the method includes at least one step of doping a semiconductor of general formula AlxGa1-xN, wherein the atomic number x represents the number between 0 and 1 with a p-type electron-accepting dopant, as well as a co-doping step with a codopant capable of modifying the structure of the valency band. The invention also concerns a semiconductor as well as its use in electronics or optoelectronics. The invention further concerns a device as well as a diode using such a semiconductor.

Abstract: According to one exemplary embodiment, a group III-V semiconductor device includes at least one transition layer situated over a substrate. The group III-V semiconductor device further includes a first strain-relieving interlayer situated over the at least one transition layer and a second strain-relieving interlayer situated over the first strain-relieving interlayer. The group III-V semiconductor device further includes a first group III-V semiconductor body situated over the second strain-relieving interlayer. The first and second strain-relieving interlayers comprise different semiconductor materials so as to reduce a strain in the first group III-V semiconductor body. The second strain-relieving interlayer can be substantially thinner than the first strain-relieving interlayer.

Abstract: A primary surface 23a of a supporting base 23 of a light-emitting diode 21a tilts by an off-angle of 10 degrees or more and less than 80 degrees from the c-plane. A semiconductor stack 25a includes an active layer having an emission peak in a wavelength range from 400 nm to 550 nm. The tilt angle “A” between the (0001) plane (the reference plane SR3 shown in FIG. 5) of the GaN supporting base and the (0001) plane of a buffer layer 33a is 0.05 degree or more and 2 degrees or less. The tilt angle “B” between the (0001) plane of the GaN supporting base (the reference plane SR4 shown in FIG. 5) and the (0001) plane of a well layer 37a is 0.05 degree or more and 2 degrees or less. The tilt angles “A” and “B” are formed in respective directions opposite to each other with reference to the c-plane of the GaN supporting base.

Abstract: A group III nitride semiconductor optical device includes: a substrate comprising a group III nitride semiconductor; a first group-III nitride semiconductor region on a primary surface of the substrate; a second group-III nitride semiconductor region on the primary surface of the substrate; and an active layer between the first group-III nitride semiconductor region and the second group-III nitride semiconductor region. The primary surface of the substrate tilts at a tilt angle in the range of 63 degrees to smaller than 80 degrees toward the m-axis of the group III nitride semiconductor from a plane perpendicular to a reference axis extending along the c-axis of the group III nitride semiconductor. The first group-III nitride semiconductor region, the active layer, and the second group-III nitride semiconductor region are arranged in the direction of the normal axis to the primary surface of the substrate. The active layer is configured to produce light having a wavelength in the range of 580 nm to 800 nm.

Abstract: Provided is an epitaxial substrate for semiconductor device that is capable of achieving a semiconductor device having high reliability in reverse characteristics of schottky junction. An epitaxial substrate for semiconductor device obtained by forming, on a base substrate, a group of group III nitride layers by lamination such that a (0001) crystal plane of each layer is approximately parallel to a substrate surface includes: a channel layer formed of a first group III nitride having a composition of Inx1Aly1Gaz1N (x1+y1+z1=1, z1>0); and a barrier layer formed of a second group III nitride having a composition of Inx2Aly2N (x2+y2=1, x2>0, y2>0), wherein the second group III nitride is a short-range-ordered mixed crystal having a short-range order parameter ? satisfying a range where 0???1.

Abstract: A group III nitride semiconductor device and a group III nitride semiconductor wafer are provided. The group III nitride semiconductor device has a channel layer comprising group III nitride-based semiconductor containing Al. The group III nitride semiconductor device can enhance the mobility of the two-dimensional electron gas and improve current characteristics. The group III nitride semiconductor wafer is used to make the group III nitride semiconductor device. The group III nitride semiconductor wafer comprises a substrate made of AlXGa1?XN (0<X?1), a first AlGaN layer made of group III nitride-based semiconductor containing Al and disposed on the substrate, and a second AlGaN layer made of group III nitride-based semiconductor having a bandgap greater than the first AlGaN layer and disposed thereon. The full width at half maximum values of X-ray rocking curves for (0002) and (10-12) planes of the first AlGaN layer are less than 1000 arcseconds.

Abstract: The present invention provides a semiconductor device including: a base substrate; a semiconductor layer which is disposed on the base substrate and has a 2-Dimensional Electron Gas (2DEG) formed therewithin; a first ohmic electrode disposed on a central region of the semiconductor layer; a second ohmic electrode which is formed on the edge regions of the semiconductor layer in such a manner to be disposed to be spaced apart from the first ohmic electrodes, and have a ring shape surrounding the first ohmic electrode; and a Schottky electrode part which is formed on the central region to cover the first ohmic electrode and is formed to be spaced apart from the second ohmic electrode.

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: The present invention makes available AlxGa(1-x)As (0?x?1) substrates, epitaxial wafers for infrared LEDs, infrared LEDs, methods of manufacturing AlxGa(1-x)As substrates, methods of manufacturing epitaxial wafers for infrared LEDs, and methods of manufacturing infrared LEDs, whereby a high level of transmissivity is maintained, and through which, in the fabrication of semiconductor devices, the devices prove to have superior characteristics. An AlxGa(1-x)As substrate (10a) of the present invention is an AlxGa(1-x)As substrate (10a) furnished with an AlxGa(1-x)As layer (11) having a major surface (11a) and, on the reverse side from the major surface (11a), a rear face (11b), and is characterized in that in the AlxGa(1-x)As layer (11), the amount fraction x of Al in the rear face (11b) is greater than the amount fraction x of Al in the major surface (11a).

Abstract: Methods of fabricating a semiconductor layer or device and said devices are disclosed. The methods include but are not limited to providing a metal or metal alloy substrate having a crystalline surface with a known lattice parameter (a). The methods further include growing a crystalline semiconductor alloy layer on the crystalline substrate surface by coincident site lattice matched epitaxy. The semiconductor layer may be grown without any buffer layer between the alloy and the crystalline surface of the substrate. The semiconductor alloy may be prepared to have a lattice parameter (a?) that is related to the lattice parameter (a). The semiconductor alloy may further be prepared to have a selected band gap.

Abstract: Implementations of quantum well photovoltaic devices are provided. In one embodiment, a photovoltaic device includes an active layer that includes a first barrier layer, a well layer located on the first barrier layer and made of a nitride semiconductor, and a second barrier layer located on the well layer. A metal layer is located adjacent to the active layer.

Abstract: A semiconductor device includes an undoped GaN layer (13), an undoped AlGaN layer (14), and a p-type GaN layer (15). In the p-type GaN layer (15), highly resistive regions (15a) are selectively formed. Resistance of the highly resistive regions (15a) can be increased by introducing a transition metal, for example, titanium.

Abstract: There are provided a Si(1-v-w-x)CwAlxNv substrate that achieves high crystallinity and low costs, an epitaxial wafer, and manufacturing methods thereof. A method for manufacturing a Si(1-v-w-x)CwAlxNv substrate according to the present invention includes the steps of preparing a different type of substrate 11 and growing a Si(1-v-w-xCwAlxNv layer having a main surface on the different type of substrate 11. The component ratio x+v at the main surface of the Si(1-v-w-x)CwAlxNv layer is 0<x+v<1. The component ratio x+v increases or decreases monotonically from the interface between the Si(1-v-w-x)CwAlxNv layer and the different type of substrate 11 to the main surface of the Si(1-v-w-x)CwAlxNv layer. The component ratio x+v at the interface between the Si(1-v-w-x)CwAlxNv layer and the different type of substrate 11 is closer to that of the material of the different type of substrate 11 than the component ratio x+v at the main surface of the Si(1-v-w-x)CwAlxNv layer.

Abstract: A method for manufacturing a compound semiconductor device includes forming a first compound semiconductor layer over a first substrate, the first compound semiconductor layer containing AlxGa1-xN (0?x<1) having a first band gap; forming a second compound semiconductor layer over the first compound semiconductor layer, the second compound semiconductor layer containing AlyInzGa1-y-zN (0<y<1, 0<y+z?1) having a second band gap larger than the first band gap; forming a compound semiconductor laminated structure over the second compound semiconductor layer; and removing the first compound semiconductor layer while irradiating the first compound semiconductor layer with light having an energy between the first band gap and the second band gap, separating the first substrate from the compound semiconductor laminated structure.

Abstract: It is an objective of the present invention to form a favorable interface between an oxide layer and a group 3-5 compound semiconductor using a practical and simple method. Provided is a semiconductor wafer comprising a first semiconductor layer that is a group 3-5 compound not containing arsenic and that lattice matches or pseudo-lattice matches with InP; and a second semiconductor layer that is formed to contact the first semiconductor layer, is a group 3-5 compound semiconductor layer that lattice matches or pseudo-lattice matches with InP, and can be selectively oxidized relative to the first semiconductor layer.

Abstract: Systems, methods, and apparatus described herein are associated with devices including hybrid electrodes. A heterostructure semiconductor transistor can include a III-N-type semiconductor heterostructure including a barrier layer overlying an active layer and a hybrid electrode region including a hybrid drain electrode region. Further, a heterostructure semiconductor rectifier can include a III-N-type semiconductor heterostructure and a hybrid electrode region including a hybrid cathode electrode region. Furthermore, the hybrid electrode region of the transistor and rectifier can include permanently trapped charge located under a Schottky contact of the hybrid electrode region.

Abstract: To obtain a device in which a buffer leak on a GaN substrate is reduced. In an HEMT device of the present invention, n-GaN (n-type GaN wafer) is used as a substrate 11. A non-doped AlpGa1-pN layer with non-uniform composition p is formed on the substrate 11 as a buffer layer 12. On the buffer layer 12, a channel layer 13 formed of semi-insulating GaN and an electron supply layer 14 formed of n-AlGaN are sequentially formed. In a composition of the buffer layer 12, a region (substrate connection region 121) where the value of p is set to 0 (p=0) (GaN) is formed on the lower end side, and a region (active layer connection region 122) where the value of p is also set to 0 (p=0) (GaN) is formed on the upper end side (channel layer 13 side). A region (high Al composition region 123) where the value of p is set to 1 (p=1) (AlN) is formed between the substrate connection region 121 and active layer connection region 122. The resistivity of the high Al composition region 123 is the highest in the buffer layer.

Abstract: A group III-nitride semiconductor Schottky diode comprises a conducting substrate having a first surface, a stack of multiple layers including a buffer layer and a semiconductor layer sequentially formed on the first surface, wherein the semiconductor layer comprises a group III nitride compound, a first electrode on the semiconductor layer, and a second electrode formed in contact with the first surface at a position adjacent to the stack of multiple layers. In other embodiments, the application also describes a method of fabricating the group III-nitride semiconductor Schottky diode.

Abstract: A nitride semiconductor chip is provided that offers enhanced luminous efficacy and an increased yield as a result of an improved EL emission pattern and improved surface morphology (flatness). This nitride semiconductor laser chip (nitride semiconductor chip) includes a GaN substrate having a principal growth plane and individual nitride semiconductor layers formed on the principal growth plane of the GaN substrate. The principal growth plane is a plane having an off angle in the a-axis direction relative to the m plane, and the individual nitride semiconductor layers include a lower clad layer of AlGaN. This lower clad layer is formed in contact with the principal growth plane of the GaN substrate.

Abstract: The invention is related to a method of obtaining bulk mono-crystalline gallium-containing nitride, comprising a step of seeded crystallization of mono-crystalline gallium-containing nitride from supercritical ammonia-containing solution, containing ions of Group I metals and ions of acceptor dopant, wherein at process conditions the molar ratio of acceptor dopant ions to supercritical ammonia-containing solvent is at least 0.0001. According to said method, after said step of seeded crystallization the method further comprises a step of annealing said nitride at the temperature between 950° C. and 1200° C., preferably between 950° C. and 1150° C. The invention covers also bulk mono-crystalline gallium-containing nitride, obtainable by the inventive method. The invention further relates to substrates for epitaxy made of mono-crystalline gallium-containing nitride and devices manufactured on such substrates.

Abstract: A semiconductor device capable of suppressing the occurrence of a punch-through phenomenon is provided. A first n-type conductive layer (2?) is formed on a substrate (1?). A p-type conductive layer (3?) is formed thereon. A second n-type conductive layer (4?) is formed thereon. On the under surface of the substrate (1?), there is a drain electrode (13?) connected to the first n-type conductive layer (2?). On the upper surface of the substrate (1?), there is a source electrode (11?) in ohmic contact with the second n-type conductive layer (4?), and a gate electrode (12?) in contact with the first n-type conductive layer (2?), p-type conductive layer (3?), the second n-type conductive layer (4?) through an insulation film (21?). The gate electrode (12?) and the source electrode (11?) are alternately arranged. The p-type conductive layer (3?) includes In.

Abstract: A nitride semiconductor device includes: a first layer made of a first nitride semiconductor; a second layer provided on the first layer and made of a second nitride semiconductor having a larger band gap than the first nitride semiconductor; a first electrode electrically connected to the second layer; a second electrode provided on the second layer and juxtaposed to the first electrode in a first direction; and a floating electrode provided on the second layer, the floating electrode including: a portion sandwiched by the second electrode in a second direction orthogonal to the first direction; and a portion protruding from the second electrode toward the first electrode.

Abstract: A material of a gate electrode is a conductive oxide having a higher work function than that of conventionally used Pd and so on, thereby achieving a normally-off transistor without reducing the sheet carrier concentration of a heterojunction. It is thus possible to achieve a normally-off operation while reducing an increase in the specific on-state resistance.

Abstract: Semiconductor devices having at least one barrier layer with a wide energy band gap are disclosed. In some embodiments, a semiconductor device includes at least one active layer, and at least one barrier layer disposed on at least one surface of the at least one active layer. The at least one barrier layer has a wider energy band gap than the energy band gap of the at least one active layer. The compounds of the active layer and the barrier layer may be selected to reduce relaxation time of an electron or hole in the active layer.

Abstract: A field effect transistor includes: a channel layer 103 containing GaN or InGaN; a first electron-supplying layer 104 disposed over the channel layer 103 and containing InxAlyGa1-x-yN (0?x<1, 0<y<1, 0<x+y<1); a first etch stop layer 105 disposed over the first electron-supplying layer 104 and containing indium aluminum nitride (InAlN); and a second electron-supplying layer 106 provided over the first etch stop layer 105 and containing InaAlbGa1-a-bN (0?a<1, 0<b<1, 0<a+b<1). A first recess 111, which extends through the second electron-supplying layer 106 and the first etch stop layer 105 and having a bottom surface constituted of a section of the first electron-supplying layer 104, is provided in the second electron-supplying layer 106 and the first etch stop layer 105. A gate electrode 109 covers the bottom surface of the first recess 111 and is disposed in the first recess 111.

Abstract: A method for manufacturing a semiconductor thin film device includes: forming a buffer layer on an Si (111) substrate and a single crystal semiconductor layer on the buffer layer; forming an island including the semiconductor layer, buffer layer, and a portion of the substrate; forming a coating layer on the island; etching the substrate along its Si (111) plane to release the island from the substrate, the coating layer serving as a mask; and bonding the released island to another substrate, a released surface of the released island contacting the another substrate. A semiconductor device includes a single crystal semiconductor layer other than Si, which has a semiconductor device formed on a front surface of an Si (111) layer lying in a (111) plane. The layer is bonded to another substrate with a back surface contacting the another substrate or a bonding layer formed on the another substrate.

Abstract: A semiconductor device includes a first semiconductor layer which is formed above a substrate, a Schottky electrode and an ohmic electrode which are formed on the first semiconductor layer to be spaced from each other and a second semiconductor layer which is formed to cover the first semiconductor layer with the Schottky electrode and the ohmic electrode exposed. The second semiconductor layer has a larger band gap than that of the first semiconductor layer.

Abstract: In various embodiments, a semiconductor device includes an aluminum nitride single-crystal substrate, a pseudomorphic strained layer disposed thereover that comprises at least one of AlN, GaN, InN, or an alloy thereof, and, disposed over the strained layer, a semiconductor layer that is lattice-mismatched to the substrate and substantially relaxed.

Abstract: A semiconductor device comprises: a heterojunction, comprises a first region comprising a first III-V semiconductor; a second region adjacent to the first region and comprising a second III-V semiconductor material, wherein the second III-V semiconductor material comprises a material of graded concentration over a width of the second region; and a third region adjacent to the second region and comprising a third III-V semiconductor material, wherein the graded concentration is selection to provide substantially no conduction band discontinuity at a junction of the second region and the third region, or to provide a type I semiconductor junction at the junction of the second region and the third region.

Abstract: An isolation layer for suppressing a leakage current is provided at least between a channel layer and a buffer layer formed under the channel layer in the buffer layer.

Abstract: A device includes a substrate; a buffer layer; and a device formation layer, wherein the buffer layer is formed by sequentially stacking, a plurality of times, a first nitride-based semiconductor layer made of a material having a lattice constant lower than a lattice constant of a material of the substrate; a first composition graded layer made of a material having a lattice constant gradually higher than the lattice constant of the first nitride-based semiconductor layer in a thickness direction; a second nitride-based semiconductor layer made of a material having a lattice constant higher than the lattice constant of the first nitride-based semiconductor layer; and a second composition graded layer made of a material having a lattice constant gradually lower than the lattice constant of the second nitride-based semiconductor layer in the thickness direction, and the second composition graded layer is thicker than the first composition graded layer.

Abstract: A semiconductor device includes a channel layer, an electron-supplying layer provided on the channel layer, a cap layer provided on the electron-supplying layer and creating lattice match with the channel layer, and ohmic electrodes provided on the cap layer. The cap layer has a composition of (InyAl1-y)zGa1-zN (0?y?1, 0?z?1). The z for such cap layer monotonically decreases as being farther away from the electron-supplying layer.