Growth technique for high efficiency gallium arsenide impatt diodes

Claim 2

A PROCESS FOR FABRICATING A HIGH EFFICIENCY GALLIUM ARSENIDE SCHOTTKY BARRIER DIODE COMPRISING. A. DEPOSITING AT LEAST ONE LAYER OF GALLIUM ARSENIDE ON A FIRST SURFACE OF A GALLIUM ARSENIDE SUBSTRATE BY VAPOR PHASE EPITAXY FROM MATERIALS INCLUDING A SOURCE OF GALLIUM, A SOURCE OF ARSENIC, AND A CONDUCTIVITY-TYPE DETERMINING IMPURITY, THE MATERIALS BEING TRANSPORTED TO THE SUBSTRATE BY A CARRIER GAS OF HYDROGEN, B. FORMING A THIN FILM OF GALLIUM ARSENIDE, RANGING IN THICKNESS FROM 100 ANGSTROMS TO 700 ANGSTROMS, WHICH INCLUDES A RELATIVELY HIGHER CONCENTRATION OF THE IMPURITY AS COMPARED WITH THE DEPOSITED GALLIUM ARSENIDE LAYER BY INJECTING SUBSTANTIALLY INSTANTANEOUSLY INTO THE CARRIER GAS AT CONSTANT PRESSURE A CONSTANT VOLUME OF A GAS CONTAINING A PREDETERMINED CONCENTRATION OF THE IMPURITY, THE INJECTION OCCURING DURING THE DEPOSITION OF THE GALLIUM ARSENIDE LAYER, C. FORMING AN ELECTRICAL CONTACT ON A SECOND SURFACE OF THE GALLIUM ARSENIDE SUBSTRATE, AND D. FORMIMG A RECTIFYING BARRIER CONTACT ON THE DEPOSITED GALLIUM ARSENIDE LAYER

Claim 3

The process of claim 1 in which prior to depositing a layer of gallium arsenide, the first surface of the gallium arsenide substrate is chloride-etched by a process including injecting substantially instantaneously into a carrier gas at constant pressure a constant volume of hydrogen chloride.

Claim 4

The process of claim 1 including: a. depositing at least one layer of gallium arsenide on a first surface of a gallium arsenide substrate by vapor phase epitaxy from materials including a source of gallium, a source of arsenic, and a conductivity-type determining impurity, the materials being transported to the substrate by a carrier gas of hydrogen; b. forming a thin film of gallium arsenide, ranging in thickness from 100 Angstroms to 700 Angstroms, which include a relatively higher concentration of the impurity as compared with the deposited gallium arsenide layer by injecting substantially instantaneously into the carrier gas at constant pressure a constant volume of a gas containing a predetermined concentration of the impurity, the injection occurring during the deposition of the gallium arsenide layer; c. continuing depositing the gallium arsenide layer to a desired thickness; d. forming an electrical contact on a second surface of the gallium arsenide substrate; and e. forming a Schottky barrier contact on the deposited gallium arsenide layer.

Claim 5

The process of claim 3 including: a. depositing in sequence two layers of gallium arsenide on a first chloride-etched surface of a gallium arsenide substrate by vapor phase epitaxy from materials including gallium, arsenic trichloride and a source of n-type determining impurity of sulfur, the materials being transported to the substrate by a carrier gas of hydrogen, in which a first layer of gallium arsenide having a carrier concentration of about 1 X 1017 cm-3 to 1 X 1018 cm-3 AND a thickness of about 2 Mu m to 6 Mu m is deposited on a gallium arsenide substrate having a resistivity of about 0.003 ohm-cm and in which a second layer of gallium arsenide having a carrier concentration of 1 X 1015 cm-3 to 1 X 1016 cm-3 and having a thickness ranging from 4 Mu m to 8 Mu m is deposited on the first layer; b. forming a thin film of gallium arsenide during deposition of the second gallium arsenide layer, the thin film ranging in thickness from 100 Angstroms to 700 Angstroms and including a carrier charge Q ranging from 1 X 1012 cm-2 to 3 X 1012 cm-2 by injecting substantially instantaneously at constant pressure a constant volume of a gas containing from 100 ppm to 1000 ppm H2S/H2; c. continuing depositing the second gallium arsenide layer to a desired thickness; d. forming an ohmic contact on a second surface of the gallium arsenide substrate; and e. forming a Schottky barrier contact on the second gallium arsenide layer.

Claim 6

The process of claim 3 which additionally includes a step of etching at least portions of the first gallium arsenide layer by a process including injecting substantially instantaneously into a carrier gas at constant pressure a constant volume of hydrogen chloride, prior to depositing the second layer of gallium arsenide.