Normally-off-type heterojunction field-effect transistor

Patent metadata

Field	Value
Publication number	US-9269801-B2
Application number	US-201214369027-A
Country	US
Kind code	B2
Filing date	Dec 12, 2012
Priority date	Dec 27, 2011
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

A normally-off-type HFET includes: an undoped Al w Ga 1-w N layer of t 1 thickness, an undoped Al x Ga 1-x N layer of t 2 thickness and an undoped GaN channel layer of t ch thickness that are sequentially stacked; a source electrode and a drain electrode separated from each other and electrically connected to the channel layer; an undoped Al y Ga 1-y N layer of t 3 thickness formed between the source electrode and the drain electrode on the channel layer; an Al z Ga 1-z N layer of t 4 thickness formed in a shape of a mesa on a partial area of the Al y Ga 1-y N layer between the source electrode and the drain electrode; and a Schottky barrier type gate electrode formed on the Al z Ga 1-z N layer, in which conditions of y>x>w>z, t 1 >t 4 >t 3 and 2wt ch /(x−w)>t 2 >1 nm are satisfied.

First claim

The invention claimed is:

1. A normally-off-type HFET comprising:
an undoped Al w Ga 1-w N layer of t 1 thickness, an undoped Al x Ga 1-x N layer of t 2 thickness and an undoped GaN channel layer of t ch thickness that are sequentially stacked;
a source electrode and a drain electrode separated from each other and electrically connected to said channel layer;
an undoped Al y Ga 1-y N layer of t 3 thickness formed between said source electrode and said drain electrode on said channel layer;
an Al z Ga 1-z N layer of t 4 thickness formed in a shape of a mesa on a partial area of said Al y Ga 1-y N layer between said source electrode and said drain electrode; and
a Schottky barrier type gate electrode formed on said Al z Ga 1-z N layer,
conditions of y>x>w>z, t 1 >t 4 >t 3 and 2wt ch /(x−w)>t 2 >1 nm being satisfied.

2. The normally-off-type HFET according to claim 1 , wherein a condition of w−z>0.03 is satisfied.

3. The normally-off-type HFET according to claim 1 , wherein a condition of t 4 /t 3 >4 is satisfied.

4. The normally-off-type HFET according to claim 1 , wherein said Al z Ga 1-z N layer is undoped.

5. The normally-off-type HFET according to claim 1 , wherein the gate electrode comprises an Ni/Au stacked layer, a WN layer, a TiN layer, a W layer, or a Ti layer.

6. The normally-off-type HFET according to claim 1 , wherein said Al w Ga 1-w N layer, said Al x Ga 1-x N layer, said GaN channel layer, said Al y Ga 1-y N layer, and said Al z Ga 1-z N layer each have a Ga polarity in which a Ga atomic plane appears on a (0001) plane of an upper surface side.

7. A normally-off-type HFET comprising:
an undoped Al w Ga 1-w N layer of t 1 thickness and an undoped GaN channel layer of t ch thickness that are sequentially stacked;
a source electrode and a drain electrode separated from each other and electrically connected to said channel layer;
an undoped Al y Ga 1-y N layer of t 3 thickness formed between said source electrode and said drain electrode on said channel layer;
an Al z Ga 1-z N layer of t 4 thickness formed in a shape of a mesa on a partial area of said Al y Ga 1-y N layer between said source electrode and said drain electrode; and
a Schottky barrier type gate electrode formed on said Al z Ga 1-z N layer,
conditions of y>w>z and t 1 >t 4 >t 3 being satisfied.

Assignees

• Sharp Kk

Inventors

• Twynam John Kevin

Classifications

• H10D62/824

  comprising only Group III-V materials heterojunctions, e.g. GaN/AlGaN heterojunctions · CPC title

• H10D62/8503

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

• H10D64/64

  Electrodes comprising a Schottky barrier to a semiconductor · CPC title

• H10D62/85

  being Group III-V materials, e.g. GaAs · CPC title

• H10D30/6738

  Schottky barrier electrodes · CPC title