Nitride semiconductor

Patent metadata

Field	Value
Publication number	US-2016254378-A1
Application number	US-201415032398-A
Country	US
Kind code	A1
Filing date	Sep 1, 2014
Priority date	Nov 6, 2013
Publication date	Sep 1, 2016
Grant date	—

Abstract

According to this GaN-based HFET, resistivity ρ of a semi-insulating film forming a gate insulating film is 3.9×10 9 Ωcm. The value of this resistivity ρ is a value derived when the current density is 6.25×10 −4 (A/cm 2 ). By inclusion of the gate insulating film by a semi-insulating film having a resistivity ρ=3.9×10 9 Ωcm, a withstand voltage of 1000 V can be obtained. Meanwhile, the withstand voltage abruptly drops as the resistivity of the gate insulating film exceeds 1×10 11 Ωcm, and the gate leak current increases when the resistivity of the gate insulating film drops below 1×10 7 Ωcm.

First claim

1 . A nitride semiconductor comprising:
a substrate; an initial growth layer formed on the substrate; a buffer layer formed on the initial growth layer; a superlattice buffer layer formed on the buffer layer; a channel layer which is formed on the superlattice buffer layer and which is composed of a plurality of layers; and a barrier layer formed on the channel layer, wherein the superlattice buffer layer is formed by alternately stacking high-Al content layers which have the composition Al x Ga 1-x N (0.5≦x≦1.0) and a thickness a and low-Al content layers which have the composition Al y Ga 1-y N (0≦y≦0.3) and a thickness b, the channel layer is joined to the superlattice buffer layer and is formed by stacking at least an Al z Ga 1-z N layer and a GaN layer in that order from the superlattice buffer layer side, and the Al composition of the AlzGa 1-z N layer is the same as the average Al composition of the superlattice buffer layer.

2 . The nitride semiconductor according to claim 1 , wherein the Al composition z of the Al z Ga 1-z N layer of the channel layer is given by the following equation:
z =( a×x+b×y )/( a+b ).

3 . The nitride semiconductor according to claim 1 , wherein the barrier layer includes an Al w Ga 1-w N layer and the Al composition w of the Al w Ga 1-w N layer is greater than the Al composition z of the Al z Ga 1-z N layer of the channel layer.

4 . The nitride semiconductor according to claim 1 , wherein the thickness a of the high-Al content layers in the superlattice buffer layer ranges from 1 nm to 5 nm and the thickness b of the low-Al content layers ranges from 22 nm to 30 nm.

5 . The nitride semiconductor according to claim 2 , wherein the barrier layer includes an Al w Ga 1-w N layer and the Al composition w of the Al w Ga 1-w N layer is greater than the Al composition z of the Al z Ga 1-z N layer of the channel layer.

6 . The nitride semiconductor according to claim 2 , wherein the thickness a of the high-Al content layers in the superlattice buffer layer ranges from 1 nm to 5 nm and the thickness b of the low-Al content layers ranges from 22 nm to 30 nm.

7 . The nitride semiconductor according to claim 3 , wherein the thickness a of the high-Al content layers in the superlattice buffer layer ranges from 1 nm to 5 nm and the thickness b of the low-Al content layers ranges from 22 nm to 30 nm.

Assignees

• Sharp Kk

Inventors

• Inoue Yushi
• Ogawa Atsushi
• Ito Nobuyuki
• Teraguchi Nobuaki

Classifications

• H10P14/3416

  Nitrides · CPC title

• H10P14/3252

  Alternating layers, e.g. superlattice · CPC title

• H10P14/3216

  Nitrides · CPC title

• H10P14/2905

  Silicon, silicon germanium or germanium · CPC title

• H10D62/8503

  Nitride Group III-V materials, e.g. AlN or GaN · CPC title