Process of making strain-free, carbon-doped epitaxial layers and products so made

Claim 2

A process of epitaxially depositing a strain-free carbon-doped p + -type GaAs layer on a substrate comprising: (a) doping with carbon a GaAs layer during its epitaxial deposition on a substrate to achieve a carbon content level in said layer of at least about 1×10 19 cm -3 ; and (b) co-doping said GaAs layer during its said epitaxial deposition with carbon doping also with an isovalent and isoelectronic dopant to strain the resultant lattice structure of said GaAs layer in a direction opposite to that induced by said carbon doping; (c) the amount of said co-dopant being proportional to the amount of carbon introduced into said GaAs layer; (d) said isovalent and isoelectric dopant being one of a group consisting of indium and antimony; (e) the amount of said indium co-dopant to counteract the strain due to said carbon-doping is derived from the following equation: ##EQU6## where a GaAs is the normal lattice constant of GaAs (5.6534 Å), a 1 is the lattice constant of carbon doped GaAs as given by equation 1, and x In is the mole fraction of indium require to be added to said carbon-doped GaAs layer.

Claim 3

The process of claim 1 wherein the counteraction of the strain due to the addition of said indium co-dopant is given by Vegard's law as a 2 =a GaAs +0.405.x In where a 2 is the lattice constant of the GaAs lattice due to the addition of indium.

Claim 4

The process of claim 1 wherein the lattice constant (a 3 ) of said carbon-doped GaAs layer is derived from the formula a 1 =a GaAs -2.0937.x C where x C is the mole fraction of carbon in the solid, based on a lattice constant of 3.5597 A for diamond.

Claim 5

The process of claim 1 wherein said proportional amount of said antimony co-dopant to said amount of carbon dopant is: ##EQU7## where x C is about 0.1, and where the lattice constant for gallium antimonide (GaSb) is 6.0954 Å.

Claim 6

A process of epitaxially growing a high performance GaAs device comprising: (a) forming a substrate of semi-insulating GaAs; (b) forming an n + -type GaAs buffer layer on said substrate; (c) forming an n + -type GaAs collector layer on said buffer layer; (d) forming a p + -type carbon-doped GaAs base layer on said collector layer, said base layer being strain-free, possessing a carbon content level of at least about 1×10 19 cm -3 and being co-doped with an isovalent and isoelectronic dopant straining the lattice structure of said GaAs base layer in a direction opposite to that induced by said carbon doping; and (e) forming an n-type GaAs emitter layer on said strain-free base layer; the amount of said co-dopant being proportional to the amount of carbon introduced into said GaAs layer, and the amount of said co-dopant to counteract the strain due to said carbon-doping being derived from the following equation: ##EQU8## where a GaAs is the normal lattice constant of GaAs (5.6534 Å), a 1 is the lattice constant of carbon doped GaAs as given by equation 1, and x In is the mole fraction of the co-dopant required to be added to said carbon-doped GaAs layer.

Claim 7

A process of epitaxially growing a high performance GaAs device comprising: (a) forming a substrate of semi-insulating GaAs; (b) forming an n + -type GaAs buffer layer on said substrate; (c) forming an n + -type GaAs collector layer on said buffer layer; (d) forming a p + -type carbon-doped GaAs base layer on said collector layer, said base layer being strain-free, possessing a carbon content level of at least about 1×10 19 cm -3 and being co-doped with an isovalent and isoelectronic dopant straining the lattice structure of said GaAs base layer in a direction opposite to that induced by said carbon doping; and (e) forming an n-type GaAs emitter layer on said strain-free base layer; the amount of said co-dopant being proportional to the amount of carbon introduced into said GaAs layer, and the amount of said co-dopant to counteract the strain due to said carbon-doping being derived from the following equation: ##EQU8## where a GaAs is the normal lattice constant of GaAs (5.6534 Å), a 1 is the lattice constant of carbon doped GaAs as given by equation 1, and x In is the mole fraction of the co-dopant required to be added to said carbon-doped GaAs layer.

Claim 8

The process of claim 5 wherein said carbon content level of said carbon-doped GaAs layer is about 1×10 20 cm -3 , and wherein said isovalent and isoelectronic dopant is one of a group of consisting of indium and antimony.

Claim 9

The process of claim 5 wherein the counteraction of the strain due to the addition of said indium co-dopant is given by Vegard's law as a 2 =a GaAs +0.405.x In where a 2 is the lattice constant of the GaAs lattice due to the addition of indium, and wherein the lattice constant (a 1 ) of said carbon-doped GaAs layer is derived from the formula a 1 =a GaAs -2.09737.x C where x C is the mole fraction of carbon in the solid, based on a lattice constant of 3.5597 Å for diamond.

Claim 10

The process of claim 7 wherein said proportional amount of said indium co-dopant to said amount of carbon dopant is: ##EQU9## where x C is about 0.1, and where the lattice constant for indium arsenide (InAs) is 6.05838 Å.

Claim 11

A process of epitaxially growing a high performance GaAs device comprising: (a) forming a substrate of semi-insulating GaAs; (b) forming an n + -type GaAs buffer layer on said substrate; (c) forming an n + -type GaAs collector layer on said buffer layer; (d) forming a p + -type carbon-doped GaAs base layer on said collector layer, said base layer being strain-free, possessing a carbon content level of at least about 1×10 19 cm -3 and being co-doped with an isovalent and isoelectronic dopant straining the lattice structure of said GaAs base layer in a direction opposite to that induced by said carbon doping; and (e) forming an n-type GaAs emitter layer on said strain-free base layer; (f) the lattice constant (a1) of said carbon-doped GaAs layer being derived from the formula a1=aGaAs-2.09737.xC where xC is the mole fraction of carbon in the solid, based on a lattice constant of 3.5597 A for diamond; (g) said isovalent and isoelectronic dopant being one of a group consisting of indium and antimony; (h) the amount of said isovalent and isoelectronic co-dopant being proportional to the amount of carbon introduced into said GaAs layer; (i) said proportional amount of said antimony co-dopant to said amount of carbon dopant being: ##EQU10## where xC is about 0.1, and where the lattice constant for gallium antimonide (GaSb) is about 6.0954 Å.

Claim 12

A process of epitaxially growing a high performance GaAs device comprising: (a) forming a substrate of semi-insulating GaAs; (b) forming an n + -type GaAs buffer layer on said substrate; (c) forming an n + -type GaAs collector layer on said buffer layer; (d) forming a p + -type carbon-doped GaAs base layer on said collector layer, said base layer being strain-free, possessing a carbon content level of at least about 1×10 19 cm -3 and being co-doped with an isovalent and isoelectronic dopant straining the lattice structure of said GaAs base layer in a direction opposite to that induced by said carbon doping; and (e) forming an n-type GaAs emitter layer on said strain-free base layer; (f) the lattice constant (a1) of said carbon-doped GaAs layer being derived from the formula a1=aGaAs-2.09737.xC where xC is the mole fraction of carbon in the solid, based on a lattice constant of 3.5597 A for diamond; (g) said isovalent and isoelectronic dopant being one of a group consisting of indium and antimony; (h) the amount of said isovalent and isoelectronic co-dopant being proportional to the amount of carbon introduced into said GaAs layer; (i) said proportional amount of said antimony co-dopant to said amount of carbon dopant being: ##EQU10## where xC is about 0.1, and where the lattice constant for gallium antimonide (GaSb) is about 6.0954 Å.