Abstract: This hetero-junction bipolar transistor includes a first n-type GaN layer, an AlxGa1-xN layer (0.1?x?0.5), an undoped GaN layer having a thickness of not less than 20 nm, a Mg-doped p-type GaN layer having a thickness of not less than 100 nm, and a second n-type GaN layer which are sequentially stacked. The first n-type GaN layer and the AlxGa1-xN layer form an emitter, the undoped GaN layer and the p-type GaN layer form a base, and the second n-type GaN layer forms a collector. During non-operation, two-dimensional hole gas is formed in a part of the undoped GaN layer near the hetero interface between the AlxGa1-xN layer and the undoped GaN layer. When the thickness of the p-type GaN layer is b [nm], the hole concentration of the p-type GaN layer is p [cm?3], and the concentration of the two-dimensional hole gas is Ps [cm?2], p×b×10?7+Ps?1×1013 [cm?2] is satisfied.

Abstract: Provided are a semiconductor device and a bidirectional field effect transistor which can easily overcome the tradeoff relation between the high voltage resistance and high speed in the semiconductor device using a polarization super junction, realize both the high voltage resistance and elimination of the occurrence of current collapse, operate at a high speed, and further the loss is low. The semiconductor device comprises a polarization super junction region and a p-electrode contact region. The polarization super junction region comprises an undoped GaN layer 11, an undoped AlxGa1-xN layer 12 with a thickness not smaller than 25 nm and not larger than 47 nm and 0.17?x?0.35, an undoped GaN layer 13 and a p-type GaN layer 14. When the reduced thickness tR is defined as tR=u+v(1+w×10?18) for the thickness u [nm] of the undoped GaN layer 13, the thickness v [nm] and the Mg concentration w [cm?3] of the p-type GaN layer 14, tR?0.864/(x?0.134)+46.0 [nm] is satisfied.

Abstract: Provided is a semiconductor element in which a two-dimensional hole gas with an enough concentration can exist, even though the p-type GaN layer is not provided on the topmost surface of the polarization super junction region. The semiconductor element comprises a polarization super junction region comprising an undoped GaN layer 11 with a thickness a [nm] (a is not smaller than 10 nm and not larger than 1000 nm), an AlxGa1-xN layer 12 and an undoped GaN layer 13. The Al composition x and the thickness t [nm] of the AlxGa1-xN layer 12 satisfy the following equation t??(a)x?(a) Where ? is expressed as Log (?)=p0+p1 log (a)+p2{log (a)}2 (p0=7.3295, p1=?3.5599, p2=0.6912) and ? is expressed as ?=p?0+p?1 log (a)+p?2{log (a)}2 (p?0=?3.6509, p?1=1.9445, p?2=?0.3793).

Abstract: A low-loss GaN-based semiconductor device is provided. The semiconductor device has the InzGa1-zN layer (where 0?z<1), the AlxGa1-xN layer (where 0<x<1), the InyGa1-yN layer (where 0?y<1) and the p-type InwGa1-wN layer (where 0?w<1) which are sequentially stacked on a base substrate of a C-plane sapphire substrate, etc. At a non-operating time, the two-dimensional hole gas is formed in the InyGa1-yN layer in the vicinity part of a hetero-interface between the AlxGa1-xN layer and the InyGa1-yN layer, and the two-dimensional electron gas is formed in the InzGa1-zN layer in the vicinity part of a hetero-interface between the InzGa1-zN layer and the AlxGa1-xN layer.

Abstract: A low-loss GaN-based semiconductor device is provided. The semiconductor device has the InzGa1-zN layer (where 0?z<1), the AlxGa1-xN layer (where 0<x<1), the InyGa1-yN layer (where 0?y<1) and the p-type InwGa1-wN layer (where 0?w<1) which are sequentially stacked on a base substrate of a C-plane sapphire substrate, etc. At a non-operating time, the two-dimensional hole gas 15 is formed in the InyGa1-yN layer in the vicinity part of a hetero-interface between the AlxGa1-xN layer and the InyGa1-yN layer, and the two-dimensional electron gases is formed in the InzGa1-zN layer in the vicinity part of a hetero-interface between the InzGa1-zN layer and the AlxGa1-xN layer.

Abstract: The method for manufacturing a semiconductor device comprises steps of: forming a growth mask with a plurality of openings directly or indirectly upon a substrate that comprises a material differing from GaN-based semiconductor; and growing a plurality of island-like GaN-based semiconductor layers upon the substrate using the growth mask in the (0001) plane orientation in a manner such that the 1-100 direction extends in a direction parallel to the striped openings of the growth mask.

Abstract: A chemical vapor deposition apparatus is provided. The chemical vapor deposition apparatus includes a susceptor support base and a susceptor, and configured to rotate the susceptor with a rotary shaft, a gap as wide as about 1 mm or more is provided along the boundary between the support base and the perimeter of the susceptor to prevent Ga from forming bridges between the support base and the susceptor during growth of III-V compound semiconductors such as GaN, thereby preventing disturbance of rotation.