Abstract: A pseudomorphic high electron mobility transistor (pHEMT) comprises: a substrate comprising a Group III-V semiconductor material; buffer layer disposed over the substrate; and a channel layer disposed over the buffer layer. The buffer layer comprises microprecipitates of a Group V semiconductor element. A method of fabricating a pHEMT is also described.

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: Two layers of protection films are formed such that a sheet resistance at a portion directly below the protection film is higher than that at a portion directly below the protection film. The protection films are formed, for example, of SiN film, as insulating films. The protection film is formed to be higher, for instance, in hydrogen concentration than the protection film so that the protection film is higher in refractive index the protection film. The protection film is formed to cover a gate electrode and extend to the vicinity of the gate electrode on an electron supplying layer. The protection film is formed on the entire surface to cover the protection film. According to this configuration, the gate leakage is significantly reduced by a relatively simple configuration to realize a highly-reliable compound semiconductor device achieving high voltage operation, high withstand voltage, and high output.

Abstract: Disclosed is a high performance nitride semiconductor having a reverse leak current characteristic with two-dimensional electron gas as a conductive layer. A desired impurity is diffused into or a nitride semiconductor to which a desired impurity is added is re-grown on the bottom surface and the side face portion of a recessed portion formed by dry etching using chlorine gas on the upper surface of a nitride semiconductor stacked film to increase resistance of the side face portion of the nitride semiconductor stacked film contacting an anode electrode, reducing the reverse leak current.

Abstract: A high performance high-electron mobility transistor (HEMT) design and methods of manufacturing the same are provided. This design introduces a bias layer in to the HEMT allowing the transistor to be fed with alternating current (AC) alone without the need for a negative direct current (DC) bias power supply.

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 transistor includes a first layer of a first type disposed over a buffer layer and having a first concentration of a first material. A first layer of a second type is disposed over the first layer of the first type, and a second layer of the first type is disposed over the first layer of the second type. The second layer of the first type having a second concentration of a first material that is greater than the first concentration of the first material. A source and a drain are spaced laterally from one another and are disposed over the buffer layer. A gate disposed over at least a portion of the second layer of the first type and disposed within a recessed area defined by the first and second layers of the first type and the first layer of the second type.

Abstract: An InGaAs n-channel quantum well heterostructure for use in a complementary transistor having a Sb-based p-channel. The heterostructure includes a buffer layer having a lattice constant intermediate that of the n- and p-channel materials and which is configured to accommodate the strain produced by a lattice-constant mismatch between the n-channel and p-channel materials.

Abstract: Portions of a top compound semiconductor layer are recessed employing a gate electrode as an etch mask to form a source trench and a drain trench. A low temperature epitaxy process is employed to deposit a semiconductor material including at least one elemental semiconductor material in the source trench and the drain trench. Metallization is performed on physically exposed surfaces of the elemental semiconductor material portions in the source trench and the drain trench by depositing a metal and inducing interaction with the metal and the at least one elemental semiconductor material. A metal semiconductor alloy of the metal and the at least one elemental semiconductor material can be performed at a temperature lower than 600° C. to provide a high electron mobility transistor with a well-defined device profile and reliable metallization contacts.

Abstract: Provided is a capacitorless memory device. The device includes a semiconductor substrate, an insulating layer disposed on the semiconductor substrate, a storage region disposed on a partial region of the insulating layer, a channel region disposed on the storage region to provide a valence band energy offset between the channel region and the storage region, a gate insulating layer and a gate electrode sequentially disposed on the channel region, and source and drain regions connected to the channel region and disposed at both sides of the gate electrode. A storage region having different valence band energy from a channel region is disposed under the channel region unit so that charges trapped in the storage region unit cannot be easily drained. Thus, a charge retention time may be increased to improve data storage capability.

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: According to an example embodiment, a power electronic device includes a first semiconductor layer, a second semiconductor layer on a first surface of the first semiconductor layer, and a source, a drain, and a gate on the second semiconductor layer. The source, drain and gate are separate from one another. The power electronic device further includes a 2-dimensional electron gas (2DEG) region at an interface between the first semiconductor layer and the second semiconductor layer, a first insulating layer on the gate and a second insulating layer adjacent to the first insulating layer. The first insulating layer has a first dielectric constant and the second insulating layer has a second dielectric constant less than the first dielectric constant.

Abstract: An insulating layer, an undoped first GaN layer and an AlGaN layer are laminated in this order on a surface of a semiconductor substrate. A surface barrier layer formed by a two-dimensional electron gas is provided in an interface between the first GaN layer and the AlGaN layer. A recess (first recess) which reaches the first GaN layer but does not pierce the first GaN layer is formed in a surface layer of the AlGaN layer. A first high withstand voltage transistor and a control circuit are formed integrally on the aforementioned semiconductor substrate. The first high withstand voltage transistor is formed in the first recess and on a surface of the AlGaN layer. The control circuit includes an n-channel MOSFET formed in part of the first recess, and a depression type n-channel MOSFET formed on a surface of the AlGaN layer.

Abstract: Enhancement-mode GaN devices having a gate spacer, a gate metal material and a gate compound that are self-aligned, and a methods of forming the same. The materials are patterned and etched using a single photo mask, which reduces manufacturing costs. An interface of the gate spacer and the gate compound has lower leakage than the interface of a dielectric film and the gate compound, thereby reducing gate leakage. In addition, an ohmic contact metal layer is used as a field plate to relieve the electric field at a doped III-V gate compound corner towards the drain contact, which leads to lower gate leakage current and improved gate reliability.

Abstract: Provided is a power device. The power device may include a two-dimensional electron gas (2-DEG) layer in a portion corresponding to a gate electrode pattern since a second nitride layer is further formed on a lower portion of the gate electrode pattern after a first nitride layer is formed and thus, may be capable of performing a normally-OFF operation. Accordingly, the power device may adjust generation of the 2-DEG layer based on a voltage of a gate, and may reduce power consumption. The power device may regrow only the portion corresponding to the gate electrode pattern or may etch a portion excluding the portion corresponding to the gate electrode pattern and thus, a recess process may be omissible, a reproducibility of the power device may be secured, and a manufacturing process may be simplified.

Abstract: According to an example embodiment, a high electron mobility transistor (HEMT) includes a substrate, a buffer layer on the substrate, a channel layer on the buffer layer, and a barrier structure on the channel layer. The buffer layer includes a 2-dimensional electron gas (2DEG). A polarization of the barrier structure varies in a region corresponding to a gate electrode. The HEMT further includes and the gate electrode, a source electrode, and a drain electrode on the barrier structure.

Abstract: A method for fabricating a semiconductor device including: forming a silicon layer on an upper face of a nitride semiconductor layer including a channel layer of a FET; thermally treating the nitride semiconductor layer in the process of forming the silicon layer or after the process of forming the silicon layer; and forming an insulating layer on an upper face of the silicon layer after the process of forming the silicon layer.

Abstract: This invention relates to a semiconductor layer structure. The semiconductor layer structure described includes a substrate and a buffer layer deposited onto the substrate. The semiconductor layer structure is characterized in that a drain voltage threshold lower than the breakdown voltage threshold is determined by isolating ions that are selectively implanted in just one region of the substrate into the substrate, wherein charge can dissipate from the one contact through the buffer layer towards a substrate region without isolating ions, if the one potential deviates from the other at least by the drain voltage threshold, and wherein the substrate region without isolating ions is located underneath the one contact. The semiconductor layer structure described allows dissipation of currents induced by induction in blocking active structures without damaging the active structures.

Abstract: A semiconductor device having a source electrode and a drain electrode formed over a semiconductor substrate, a gate electrode formed over the semiconductor substrate and disposed between the source electrode and the drain electrode, a protection film made of an insulating material and formed between the source electrode and the gate electrode and between the drain electrode and the gate electrode, and a gate side opening formed at least in one of a portion of the protection film-between the source electrode and the gate electrode and a portion of the protection film between the drain electrode and the gate electrode and disposed away from all of the gate electrode, the source electrode and the drain electrode.

Abstract: A High Electron Mobility Transistor (HEMT) includes a first III-V compound layer having a first band gap, and a second III-V compound layer having a second band gap over the first III-V compound layer. The second band gap is greater than the first band gap. A crystalline interfacial layer is overlying and in contact with the second III-V compound layer. A gate dielectric is over the crystalline interfacial layer. A gate electrode is over the gate dielectric. A source region and a drain region are over the second III-V compound layer, and are on opposite sides of the gate electrode.

Abstract: High electron mobility transistors (HEMTs) and methods of manufacturing the same. A HEMT may include a channel layer and a channel supply layer, and the channel supply layer may be a multilayer structure. The channel supply layer may include an etch stop layer and an upper layer on the etch stop layer. A recess region may be in the upper layer. The recess region may be a region recessed to an interface between the upper layer and the etch stop layer. A gate electrode may be on the recess region.

Abstract: There are disclosed herein various implementations of a semiconductor structure and method. The semiconductor structure comprises a substrate, a transition body over the substrate, and a group III-V intermediate body having a bottom surface over the transition body. The semiconductor structure also includes a group III-V device layer over a top surface of the group III-V intermediate body. The group III-V intermediate body has a continuously reduced impurity concentration wherein a higher impurity concentration at the bottom surface is continuously reduced to a lower impurity concentration at the top surface.

Abstract: A compound semiconductor device includes a compound semiconductor laminated structure, a passivation film formed on the compound semiconductor laminated structure and having a through-hole, and a gate electrode formed on the passivation film so as to plug the through-hole. A grain boundary between different crystalline orientations is formed in the gate electrode, and a starting point of the grain boundary is located apart from the through-hole on a flat surface of the passivation film.

Abstract: A circuit structure includes a substrate, a nucleation layer of undoped aluminum nitride, a graded buffer layer comprising aluminum, gallium, nitrogen, one of silicon and oxygen, and a p-type conductivity dopant, a ungraded buffer layer comprising gallium, nitrogen, one of silicon and oxygen, and a p-type conductivity dopant without aluminum, and a bulk layer of undoped gallium nitride over the ungraded buffer layer. The various dopants in the graded buffer layer and the ungraded buffer layer increases resistivity and results in layers having an intrinsically balanced conductivity.

Abstract: The present invention reduces the dynamic on resistance in the channel layer of a GaN device by etching a void in the nucleation and buffer layers between the gate and the drain. This void and the underside of the device substrate may be plated to form a back gate metal layer. The present invention increases the device breakdown voltage by reducing the electric field strength from the gate to the drain of a HEMT. This electric field strength is reduced by placing a back gate metal layer below the active region of the channel. The back gate metal layer may be in electrical contact with the source or drain.

Abstract: According to example embodiments, a HEMT includes a channel layer, a channel supply layer on the channel layer, a source electrode and a drain electrode spaced apart on the channel layer, a depletion-forming layer on the channel supply layer, and a plurality of gate electrodes on the depletion-forming layer between the source electrode and the drain electrode. The channel supply layer is configured to induce a two-dimensional electron gas (2DEG) in the channel layer. The depletion-forming layer is configured to form a depletion region in the 2DEG. The plurality of gate electrodes include a first gate electrode and a second gate electrode spaced apart from each other.

Abstract: To provide a semiconductor device in which a rectifying element capable of reducing a leak current in reverse bias when a high voltage is applied and reducing a forward voltage drop Vf and a transistor element are integrally formed on a single substrate. A semiconductor device has a transistor element and a rectifying element on a single substrate. The transistor element has an active layer formed on the substrate and three electrodes (source electrode, drain electrode, and gate electrode) disposed on the active layer. The rectifying element has an anode electrode disposed on the active layer, a cathode electrode which is the drain electrode, and a first auxiliary electrode between the anode electrode and cathode electrode.

Abstract: A semiconductor device containing a GaN FET has n-type doping in at least one III-N semiconductor layer of a low-defect layer and an electrical isolation layer below a barrier layer. A sheet charge carrier density of the n-type doping is 1 percent to 200 percent of a sheet charge carrier density of the two-dimensional electron gas.

Abstract: The invention relates to a method for producing silicon semiconductor wafers and components having layer structures of III-V layers for integrating III-V semiconductor components. The method employs SOI silicon semiconductor wafers having varying substrate orientations, and the III-V semiconductor layers are produced in trenches (28, 43, 70) produced by etching within certain regions (38, 39), which are electrically insulated from each other, of the active semiconductor layer (24, 42) by means of a cover layer or cover layers (29) using MOCVD methods.

Abstract: Disclosed are embodiments of a junction field effect transistor (JFET) structure with one or more P-type silicon germanium (SiGe) or silicon germanium carbide (SiGeC) gates (i.e., a SiGe or SiGeC based heterojunction JFET). The P-type SiGe or SiGeC gate(s) allow for a lower pinch off voltage (i.e., lower Voff) without increasing the on resistance (Ron). Specifically, SiGe or SiGeC material in a P-type gate limits P-type dopant out diffusion and, thereby ensures that the P-type gate-to-N-type channel region junction is more clearly defined (i.e., abrupt as opposed to graded). By clearly defining this junction, the depletion layer in the N-type channel region is extended. Extending the depletion layer in turn allows for a faster pinch off (i.e., requires lower Voff). P-type SiGe or SiGeC gate(s) can be incorporated into conventional lateral JFET structures and/or vertical JFET structures. Also disclosed herein are embodiments of a method of forming such a JFET structure.

Abstract: The present invention relates to fabrication of enhancement mode and depletion mode High Electron Mobility Field Effect Transistors on the same die separated by as little as 10 nm. The fabrication method uses selective decomposition and selective regrowth of the Barrier layer and the Cap layer to engineer the bandgap of a region on a die to form an enhancement mode region. In these regions zero or more devices may be fabricated.

Abstract: There is provided a light emitting device in which low power consumption can be realized even in the case of a large screen. The surface of a source signal line or a power supply line in a pixel portion is plated to reduce a resistance of a wiring. The source signal line in the pixel portion is manufactured by a step different from a source signal line in a driver circuit portion. The power supply line in the pixel portion is manufactured by a step different from a power supply line led on a substrate. A terminal is similarly plated to made the resistance reduction. It is desirable that a wiring before plating is made of the same material as a gate electrode and the surface of the wiring is plated to form the source signal line or the power supply line.

Abstract: An i-GaN layer (electron transit layer), an n-GaN layer (compound semiconductor layer) formed over the i-GaN layer (electron transit layer), and a source electrode, a drain electrode and a gate electrode formed over the n-GaN layer (compound semiconductor layer) are provided. A recess portion is formed inside an area between the source electrode and the drain electrode of the n-GaN layer (compound semiconductor layer) and at a portion separating from the gate electrode.

Abstract: There are provided a semiconductor device and a method for manufacturing the same.

Abstract: A compound semiconductor device includes: a compound semiconductor multilayer structure; a gate insulating film on the compound semiconductor multilayer structure; and a gate electrode, wherein the gate electrode includes a gate base portion on the gate insulating film and a gate umbrella portion, and a surface of the gate umbrella portion includes a Schottky contact with the compound semiconductor multilayer structure.

Abstract: A protection clamp is provided between a first terminal and a second terminal, and includes a multi-gate high electron mobility transistor (HEMT), a current limiting circuit, and a forward trigger control circuit. The multi-gate HEMT includes a drain/source, a source/drain, a first depletion-mode (D-mode) gate, a second D-mode gate, and an enhancement-mode (E-mode) gate disposed between the first and second D-mode gates. The drain/source and the first D-mode gate are connected to the first terminal and the source/drain and the second D-mode gate are connected to the second terminal. The forward trigger control and the current limiting circuits are coupled between the E-mode gate and the first and second terminals, respectively. The forward trigger control circuit provides an activation voltage to the E-mode gate when a voltage of the first terminal exceeds a voltage of the second terminal by a forward trigger voltage.

Abstract: The present invention relates to a nitride semiconductor device One aspect of the present invention provides 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.

Abstract: In one embodiment, a floating body field-effect transistor includes a pair of source/drain regions having a floating body channel region received therebetween. The source/drain regions and the floating body channel region are received over an insulator. A gate electrode is proximate the floating body channel region. A gate dielectric is received between the gate electrode and the floating body channel region. The floating body channel region has a semiconductor SixGe(1-x)-comprising region. The floating body channel region has a semiconductor silicon-comprising region received between the semiconductor SixGe(1-x)-comprising region and the gate dielectric. The semiconductor SixGe(1-x)-comprising region has greater quantity of Ge than any quantity of Ge within the semiconductor silicon-comprising region. Other embodiments are contemplated, including methods of forming floating body field-effect transistors.

Abstract: Substrates of GaN over silicon suitable for forming electronics devices such as heterostructure field effect transistors (HFETs), and methods of making the substrates, are disclosed. Voids in a crystalline Al2O3 film on a top surface of a silicon wafer are formed. The top surface of the silicon wafer is along the <111> silicon crystal orientation. A plurality of laminate layers is deposited over the voids and the Al2O3 film. Each laminate layer includes an AN film and a GaN film. A transistor or other device may be formed in the top GaN film.

Abstract: A semiconductor device includes a nitride semiconductor layer having a (0001) face and a (000-1) face, formed above a common substrate; a (0001) face forming layer provided partially between the substrate and the nitride semiconductor layer; a source electrode, a drain electrode, and a gate electrode, provided on the nitride semiconductor layer having the (0001) face; and a hole extracting electrode provided on the nitride semiconductor layer having the (000-1) face.

Abstract: A compound semiconductor device includes a plurality of high-resistance crystalline silicon epitaxial layers and a plurality of activated dopant regions disposed in a same region of at least some of the epitaxial layers so that the activated dopant regions are aligned in a vertical direction perpendicular to a main surface of the epitaxial layers. The compound semiconductor device further includes an III-nitride compound semiconductor device structure disposed on the main surface of the epitaxial layers. The III-nitride compound semiconductor device structure has a source, a drain and a gate. An electrically conductive structure is formed from the activated dopant regions. The electrically conductive structure extends in the vertical direction through the epitaxial layers with the activated dopant regions toward the III-nitride compound semiconductor device structure, and is electrically connected to the source.

Abstract: A method of manufacturing a heterostructure device is provided that includes implantation of ions into a portion of a surface of a multi-layer structure. Iodine ions are implanted between a first region and a second region to form a third region. A charge is depleted from the two dimensional electron gas (2DEG) channel in the third region to form a reversibly electrically non-conductive pathway from the first region to the second region. On applying a voltage potential to a gate electrode proximate to the third region allows electrical current to flow from the first region to the second region.

Abstract: A method for fabricating a gate structure for a field effect transistor having a buffer layer on a substrate, a channel layer and a barrier layer over the channel layer includes forming a gate of a first dielectric, forming first sidewalls of a second dielectric on either side and adjacent to the gate, selectively etching into the buffer layer to form a mesa for the field effect transistor, depositing a dielectric layer over the mesa, planarizing the dielectric layer over the mesa to form a planarized surface such that a top of the gate, tops of the first sidewalls, and a top of the dielectric layer over the mesa are on the same planarized surface, depositing metal on the planzarized surface, annealing to form the gate into a metal silicided gate, and etching to remove excess non-silicided metal.

Abstract: A semiconductor device including at least a p-channel field-effect transistor region formed above a compound semiconductor substrate. The p-channel field-effect transistor region includes an undoped buffer layer; a p-type channel layer formed in contact with the buffer layer; a p-type source region and a p-type drain region formed in the channel layer, being separated with each other; and an n-type gate region formed above the channel layer and between the source region and the drain region. The buffer layer is formed having either a multilayer structure including a hole diffusion control layer with a band gap larger than the channel layer, or a single layer structure including only the hole diffusion control layer.

Abstract: Semiconductor devices and methods for making semiconductor devices are disclosed herein. A method configured in accordance with a particular embodiment includes forming a stack of semiconductor materials from an epitaxial substrate, where the stack of semiconductor materials defines a heterojunction, and where the stack of semiconductor materials and the epitaxial substrate further define a bulk region that includes a portion of the semiconductor stack adjacent the epitaxial substrate. The method further includes attaching the stack of semiconductor materials to a carrier, where the carrier is configured to provide a signal path to the heterojunction. The method also includes exposing the bulk region by removing the epitaxial substrate.

Abstract: Embodiments include high electron mobility transistors (HEMT). In embodiments, a gate electrode is spaced apart by different distances from a source and drain semiconductor region to provide high breakdown voltage and low on-state resistance. In embodiments, self-alignment techniques are applied to form a dielectric liner in trenches and over an intervening mandrel to independently define a gate length, gate-source length, and gate-drain length with a single masking operation. In embodiments, III-N HEMTs include fluorine doped semiconductor barrier layers for threshold voltage tuning and/or enhancement mode operation.

Abstract: A predisposed high electron mobility transistor (HEMT) is disclosed. The predisposed HEMT includes a buffer layer, a HEMT channel layer on the buffer layer, a first HEMT barrier layer over the HEMT channel layer, and a HEMT cap layer on the first HEMT barrier layer. The HEMT cap layer has a drain region, a source region, and a gate region. Further, the HEMT cap layer has a continuous surface on the drain region, the source region, and the gate region. When no external voltage is applied between the source region and the gate region, the gate region either depletes carriers from the HEMT channel layer or provides carriers to the HEMT channel layer, thereby selecting a predisposed state of the predisposed HEMT.

Abstract: A protection circuit including a multi-gate high electron mobility transistor (HEMT), a forward conduction control block, and a reverse conduction control block is provided between a first terminal and a second terminal. The multi-gate HEMT includes an explicit drain/source, a first depletion-mode (D-mode) gate, a first enhancement-mode (E-mode) gate, a second E-mode gate, a second D-mode gate, and an explicit source/drain. The drain/source and the first D-mode gate are connected to the first terminal and the source/drain and the second D-mode gate are connected to the second terminal. The forward conduction control block turns on the second E-mode gate when a voltage difference between the first and second terminals is greater than a forward conduction trigger voltage, and the reverse conduction control block turns on the first E-mode gate when the voltage difference is more negative than a reverse conduction trigger voltage.

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: The present invention provides a semiconductor device having such a structure formed by sequentially laminating a lower barrier layer composed of lattice-relaxed AlxGa1-xN (0?x?1), a channel layer composed of InyGa1-yN (0?y?1) with compressive strain and a contact layer composed of AlzGa1-zN (0?z?1), wherein a two-dimensional electron gas is produced in the vicinity of an interface of said InyGa1-yN channel layer with said AlzGa1-zN contact layer; a gate electrode is formed so as to be embedded in the recessed portion with intervention of an insulating film, which recessed portion is formed by removing a part of said AlzGa1-zN contact layer by etching it away until said InyGa1-yN channel layer is exposed; and, ohmic electrodes are formed on the AlzGa1-zN contact layer. Thus, the semiconductor device has superior uniformity and reproducibility of the threshold voltage while maintaining a low gate leakage current, and is also applicable to the enhancement mode type.