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US 4,968,642 AGranted
Method of making a gallium arsenide phosphide-, mixed crystal-epitaxial wafer
AssigneeMitsubishi Chemical Industries Limited
InventorsHisanori Fujita, Masaaki Kanayama, Takeshi Okano
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Abstract
An epitaxial wafer for producing arrays of GaAsP-LEDs comprises, in the GaAs.sub.1-x P.sub.x layer with varying X, a layer region(s) with a discontinuous variance of x along the thickness of the GaAs.sub.1-x P.sub.x layer. This layer region(s) contribute to a uniformity in the brightness of the light emission of LEDs formed in the epitaxial wafer.
Claims8
A process for preparing a graded gallium phosphide mixed crystal on a substrate which comprises:
- (1) heating a substrate on which the graded layer is to be deposited to a gallium arsenide phosphide graded mixed crystal forming temperature;
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- (2) contacting the heated substrate with a gaseous mixture containing HCl, phosphine, arsine, gallium chloride, a gaseous dopant and hydrogen, wherein the atomic ratio of arsenic to phosphorus is varied from about 56:1 to about 3.5:1, and the gaseous mixture always contains arsenic and phosphorus during the graded mixed crystal deposition for a sufficient length of time to form the mixed crystal graded layer.
A process for preparing a graded gallium arsenide phosphide mixed crystal on a substrate which comprises:
- (1) placing a crystalline substrate of gallium arsenide or gallium phosphide in an epitaxial reactor;
- (2) placing metallic gallium, at a separate location, in said reactor;
- (3) replacing the air in said reactor with an inert gas, and thereafter introducing hydrogen gas while raising the reactor temperature;
- (4) after the temperature of the metallic-gallium reaches about 830.degree. C., and the temperature of the substrate reaches about 750.degree. C., a gaseous HCl is introduced into said reactor downstream of said metallic-gallium to etch the substrate;
- (5) discontinuing the gaseous HCl and feeding into the reactor hydrogen gas containing diethyltellurium;
- (6) introducing gaseous HCl into the reactor so that it comes into contact with the surface of the metallic gallium;
- (7) subsequently feeding arsine and phosphine, in a hydrogen gas, into the reactor to form a graded layer, and wherein the flow rate of arsine is gradually decreased and the flow rate of phosphine gradually increased for a period of time to form a graded layer;
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- (8) thereafter maintaining the flow rates constant to form a constant layer.
6 more elements
Dependencies are inferred from the claim text.