Abstract: A semiconductor device 100 contains an undoped GaN channel layer 105, an AlGaN electron donor layer 106 provided on the undoped GaN channel layer 105 as being brought into contact therewith, an undoped GaN layer 107 provided on the AlGaN electron donor layer 106, a source electrode 101 and a drain electrode 103 provided on the undoped GaN layer 107 as being spaced from each other, a recess 111 provided in the region between the source electrode 101 and the drain electrode 103, as being extended through the undoped GaN layer 107, a gate electrode 102 buried in the recess 111 as being brought into contact with the AlGaN electron donor layer 106 on the bottom surface thereof, and an SiN film 108 provided on the undoped GaN layer 107, in the region between the gate electrode 102 and the drain electrode 103.

Abstract: In a group III nitride-type field effect transistor, the present invention reduces a leak current component by conduction of residual carriers in a buffer layer, and achieves improvement in a break-down voltage, and enhances a carrier confinement effect (carrier confinement) of a channel to improve pinch-off characteristics (to suppress a short channel effect). For example, when applying the present invention to a GaN-type field effect transistor, besides GaN of a channel layer, a composition-modulated (composition-gradient) AlGaN layer in which aluminum composition reduces toward a top gradually or stepwise is used as a buffer layer (hetero buffer).

Abstract: An electron supply layer (13) is a layer which forms a heterojunction with a channel layer (12) and contains InzAlxGa1-zxN (0?z<1, 0<x<1, 0<x+z<1). On the electron supply layer (13), a gate electrode (17) is formed in contact with the electron supply layer (13). The Al composition ratio x1 at the interface between the electron supply layer (13) and the channel layer (12) and the Al composition ratio xa at the interface between the electron supply layer (13) and the gate electrode (17) satisfy the following conditions: x1/2?xa<x1 and x1?0.3.

Abstract: An ohmic electrode structure of a nitride semiconductor device having a nitride semiconductor. The ohmic electrode structure is provided with a first metal film formed on the nitride semiconductor and a second metal film formed on the first metal film. The first metal film is composed of at least one material selected from a group consisting of V, Mo, Ti, Nb, W, Fe, Hf, Re, Ta and Zr. The second metal film is composed of at least one material different from that of the first metal film (102), selected from a group consisting of V, Mo, Ti, Nb, W, Fe, Hf, Re, Ta, Zr, Pt and Au.

Abstract: There is provided a technology for obtaining an electrode having a low contact resistance and less surface roughness. There is provided an electrode comprising a semiconductor film 101, and a first metal layer 102 and a second metal layer 103 sequentially stacked in this order on the semiconductor film 101, characterized in that the first metal film 102 is formed of Al, and the second metal film 103 is formed of at least one metal selected from the group consisting of Nb, W, Fe, Hf, Re, Ta and Zr.

Abstract: There is provided a technology for obtaining an electrode having a low contact resistance and less surface roughness. There is provided an electrode comprising a semiconductor film 101, and a first metal layer 102 and a second metal layer 103 sequentially stacked in this order on the semiconductor film 101, characterized in that the first metal film 102 is formed of Al, and the second metal film 103 is formed of at least one metal selected from the group consisting of Nb, W, Fe, Hf, Re, Ta and Zr.

Abstract: The present invention provides a Schottky electrode for a nitride semiconductor device having a high barrier height, a low leak current performance and a low resistance and being thermally stable, and a process for production thereof. The Schottky electrode for a nitride semiconductor has a layered structure that comprises a copper (Cu) layer being in contact with the nitride semiconductor and a first electrode material layer formed on the copper (Cu) layer as an upper layer. As the first electrode material, a metal material which has a thermal expansion coefficient smaller than the thermal expansion coefficient of copper (Cu) and starts to undergo a solid phase reaction with copper (Cu) at a temperature of 400° C. or higher is employed.

Abstract: An electric-field control electrode (5) is formed between a gate electrode (2) and a drain electrode (3). A multilayered film including a SiN film (21) and a SiO2 film (22) is formed below the electric-field control electrode (5). The SiN film (21) is formed so that a surface of an AlGaN electron supply layer (13) is covered with the SiN film (21).

Abstract: A field effect transistor includes a semiconductor layer structure including GaN channel layer 12 and AlGa electron supply layer 13, source electrode 1 and drain electrode 3 which are formed on electron supply layer 13 so as to be separated from each other, gate electrode 2 formed between source electrode 1 and drain electrode 3, and SiON film 23 formed on electron supply layer 13. Gate electrode 2 has a field plate portion 5 that projects toward drain electrode 3 in the form of an eave on SiON film 23. The thickness of a portion (field plate layer 23a) of SiON film 23 lying between field plate portion 5 and electron supply layer 13 gradually increases from gate electrode 2 to drain electrode 3.

Abstract: An ohmic electrode structure of a nitride semiconductor device having a nitride semiconductor. The ohmic electrode structure is provided with a first metal film formed on the nitride semiconductor and a second metal film formed on the first metal film. The first metal film is composed of at least one material selected from a group consisting of V, Mo, Ti, Nb, W, Fe, Hf, Re, Ta and Zr. The second metal film is composed of at least one material different from that of the first metal film (102), selected from a group consisting of V, Mo, Ti, Nb, W, Fe, Hf, Re, Ta, Zr, Pt and Au.

Abstract: The present invention provides a semiconductor device capable of suppressing current collapse, and also of preventing dielectric breakdown voltage and gain from lowering so as to perform high-voltage operation and realize an ideal high output. On a substrate (101), there are formed a buffer layer (102) made of a first GaN-based semiconductor, a carrier traveling layer (103) made of a second GaN-based semiconductor and a carrier supplying layer (104) made of a third GaN-based semiconductor. A recess structure (108) is made by eliminating a part of a first insulation film (107) and a part of the carrier supplying layer (104). Next, a gate insulation film (109) is deposited, and then a gate electrode (110) is formed so as to fill up the recess portion (108) and cover on over an area where the first insulation film (107) remains so that its portion on the drain electrode side is longer than that on the source electrode side.

Abstract: There is provided a technology for obtaining an electrode having a low contact resistance and less surface roughness. There is provided an electrode comprising a semiconductor film 101, and a first metal layer 102 and a second metal layer 103 sequentially stacked in this order on the semiconductor film 101, characterized in that the first metal film 102 is formed of Al, and the second metal film 103 is formed of at least one metal selected from the group consisting of Nb, W, Fe, Hf, Re, Ta and Zr.

Abstract: A GaN semiconductor device with improved heat resistance of the Schottky junction electrode and excellent power performance and reliability is provided. In this semiconductor device having a Schottky gate electrode 17 which is in contact with an AlGaN electron supplying layer 14, a gate electrode 17 comprises a laminated structure wherein a first metal layer 171 formed of any of Ni, Pt and Pd, a second metal layer 172 formed of any of Mo, Pt, W, Ti, Ta, MoSi, PtSi, WSi, TiSi, TaSi, MoN, WN, TiN and TaN, and a third metal layer formed of any of Au, Cu, Al and Pt. Since the second metal layer comprises a metal material having a high melting point, it works as a barrier to the interdiffusion between the first metal layer and the third metal layer, and the deterioration of the gate characteristics caused by high temperature operation is suppressed.

Abstract: A field plate portion (5) overhanging a drain side in a visored shape is formed in a gate electrode (2). A multilayered film including a SiN film (21) and a SiO2 film (22) is formed beneath the field plate portion (5). The SiN film (21) is formed so that a surface of an AlGaN electron supply layer (13) is covered therewith.

Abstract: A semiconductor device includes, on a substrate (101), a buffer layer (102), and an channel layer (104), consisting essentially of semiconductor of a wultzite compound of group III-V, having a (0001) plane as a principal plane. The channel layer is subjected to compressive strain. A carrier supplying layer (103) is interposed between the channel layer (104) and the buffer layer (102). The carrier supplying layer (103) consists essentially of semiconductor of a wultzite compound of group III-V as a main component. N-type impurities are doped into the entire or part of the carrier supplying layer (103).

Abstract: An electric-field control electrode (5) is formed between a gate electrode (2) and a drain electrode (3). A multilayered film including a SiN film (21) and a SiO2 film (22) is formed below the electric-field control electrode (5). The SiN film (21) is formed so that a surface of an AlGaN electron supply layer (13) is covered with the SiN film (21).

Abstract: A GaN semiconductor device with improved heat resistance of the Schottky junction electrode and excellent power performance and reliability is provided. In this semiconductor device having a Schottky gate electrode 17 which is in contact with an AlGaN electron supplying layer 14, a gate electrode 17 comprises a laminated structure wherein a first metal layer 171 formed of any of Ni, Pt and Pd, a second metal layer 172 formed of any of Mo, Pt, W, Ti, Ta, MoSi, PtSi, WSi, TiSi, TaSi, MoN, WN, TiN and TaN, and a third metal layer formed of any of Au, Cu, Al and Pt. Since the second metal layer comprises a metal material having a high melting point, it works as a barrier to the interdiffusion between the first metal layer and the third metal layer, and the deterioration of the gate characteristics caused by high temperature operation is suppressed.

Abstract: A group III nitride semiconductor device of field effect transistor type having improved productivity, reduced parasitic capacitances adapted for excellent device performance in high-speed operation as well as good heat diffusion characteristics. The device includes an epitaxial growth layer of a group III nitride semiconductor with a buffer layer laid under it, formed on an A plane (an (11-20) plane) of a sapphire. Thereon a gate electrode, a source electrode, a drain electrode, and pad electrodes are formed, and a ground conductor layer is formed on the back face of the sapphire substrate. A thickness of said sapphire substrate tsub satisfies the following Equation (1).

Abstract: An object of the present invention is to improve, in a group III nitride semiconductor device, the productivity, the heat diffusion characteristic and the device performance in high-speed operation, and, therefor, in a group III nitride semiconductor device of the present invention, an epitaxial growth layer 13 of a group III nitride semiconductor with a buffer layer 12 laid under it is formed on a sapphire substrate 11 in which an A plane (an (11-20) plane) is set to be the principal plane, and thereon a gate electrode 16, a source electrode 15 and a drain electrode 17 are formed, wherein a thickness of the single crystalline sapphire substrate is specifically set to be 100 &mgr;m or less.

Abstract: A hetero-junction FET has an intermediate layer including n-type-impurity doped layer between an electron supply layer and an n-type cap layer. The intermediate layer cancels the polarized negative charge generated between the electron supply layer and the n-type cap layer by ionized positive charge, thereby reducing the barrier against the electrons and source/drain resistance.