High electron mobility transistor comprising an InAs/InGaAs superlattice

Claim 2

The device as set forth in claim 1, further comprising an InAlAs charge supply layer (5) formed between said InGaAs channel layer and said superlattice layer.

Claim 3

The device as set forth in claim 1, further comprising: a first InAlAs layer (6a) formed beneath said superlattice layer; and a second InAlAs layer (6b) formed on said superlattice layer.

Claim 4

The device as set forth in claim 1, wherein a ratio of an average lattice constant of said superlattice layer to a lattice constant of said InP substrate is approximately 0.995 to 1.005.

Claim 5

The device as set forth in claim 1, wherein each of said InAs and said AlAs of said superlattice layer is thinner than approximately 4 nm.

Claim 6

The device as set forth in claim 1, wherein a thickness ratio of said InAs and said AlAs of said superlattice layer is approximately 0.5 to 2.

Claim 7

The device as set forth in claim 1, wherein said superlattice layer is thinner than approximately 25 nm.

Claim 8

A heterojunction field effect type semiconductor device comprising: an Inp substrate (1); an InGaAs channel layer (3) formed over said InP substrate; and a superlattice layer (13, 14, 17, 18) formed by periods of InAs/AlGaAs and over said InGaAs channel layer.

Claim 9

The device as set forth in claim 8, further comprising an InAlAs charge supply layer (5) formed between said InGaAs channel layer and said superlattice layer.

Claim 10

The device as set forth in claim 8, further comprising: a first InAlAs layer (6a) formed beneath said superlattice layer; and a second InAlAs layer (6b) formed on said superlattice layer.

Claim 11

The device as set forth in claim 8, wherein a ratio of an average lattice constant of said superlattice layer to a lattice constant of said InP substrate is approximately 0.995 to 1.005.

Claim 12

The device as set forth in claim 8, wherein each of said InAs and said AlGaAs of said superlattice layer is thinner than approximately 4 nm.

Claim 13

The device as set forth in claim 8, wherein a thickness ratio of said InAs and said AlGaAs of said superlattice layer is approximately 0.5 to 2.

Claim 14

The device as set forth in claim 9, wherein said superlattice layer is thinner than approximately 25 nm.

Claim 15

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a superlattice layer (11) formed by periods of one two-molecules-thick InAs layer (11a) and one three-molecules-thick AlAs layer (11b) on said InAlAs carrier supply layer; and electrodes (7S, 7D, 7G) formed on said superlattice layer.

Claim 16

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a superlattice layer (12) formed by periods of one two-molecules-thick InAs layer (12a) and one two-molecules-thick AlAs layer (12b) on said InAlAs carrier supply layer; and electrodes (7S, 7D, 7G) formed on said superlattice layer.

Claim 17

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a superlattice layer (13) formed by periods of one two-molecules-thick InAs layer (13a) and one three-molecules-thick AlGaAs layer (13b) on said InAlAs carrier supply layer; and electrodes (7S, 7D, 7G) formed on said superlattice layer.

Claim 18

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a superlattice layer (14) formed by periods of one two-molecules-thick InAs layer (14a) and one two-molecules-thick AlGaAs layer (14b) on said InAlAs carrier supply layer; and electrodes (7S, 7D, 7G) formed on said superlattice layer.

Claim 19

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a first InAlAs Schottky layer (6a) formed on said InAlAs carrier supply layer; a superlattice layer (15) formed by periods of one two-molecules-thick InAs layer (15a) and one four-molecules-thick AlAs layer (15b) on said first InAlAs Schottky layer; s second InAlAs Schottky layer (6b) formed on said supperlattice layer; and electrodes (7S, 7D, 7G) formed on said second InAlAs Schottky layer.

Claim 20

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a first InAlAs Schottky layer (6a) formed on said InAlAs carrier supply layer; a superlattice layer (16) formed by periods of one two-molecules-thick InAs layer (16a) and one two-molecules-thick AlAs layer (16b) on said first InAlAs Schottky layer; s second InAlAs Schottky layer (6b) formed on said supperlattice layer; and electrodes (7S, 7D, 7G) formed on said second InAlAs Schottky layer.

Claim 21

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a first InAlAs Schottky layer (6a) formed on said InAlAs carrier supply layer; a superlattice layer (17) formed by periods of one two-molecules-thick InGaAs layer (17a) and one four-molecules-thick AlAs layer (17b) on said first InAlAs Schottky layer; s second InAlAs Schottky layer (6b) formed on said supperlattice layer; and electrodes (7S, 7D, 7G) formed on said second InAlAs Schottky layer.

Claim 22

A heterojunction field effect type semiconductor device comprising: an InP substrate (1); an undoped InAlAs buffer layer (2) formed on said InP substrate; an undoped InGaAs channel layer (3) formed on said InAlAs buffer layer; an undoped InAlAs spacer layer (4) formed on said InGaAs channel layer; a doped InAlAs carrier supply layer (5) formed on said InAlAs spacer layer; a first InAlAs Schottky layer (6a) formed on said InAlAs carrier supply layer; a superlattice layer (18) formed by periods of one two-molecules-thick InAs layer (18a) and one two-molecules-thick AlGaAs layer (18b) on said first InAlAs Schottky layer; s second InAlAs Schottky layer (6b) formed on said supperlattice layer; and electrodes (7S, 7D, 7G) formed on said second InAlAs Schottky layer.