Method for making uniform single crystal semiconductors epitaxially

Claim 2

covering the seed with a saturated solution of gallium and gallium arsenide, the solution being at a first temperature higher than the minimum nucleation temperature of gallium arsenide, while maintaining the seed at a second temperature lower than the first temperature, and

Claim 3

A process for growing single crystal semiconductor gallium arsenide in an open tube and in an atmosphere of a gas which is non-reactive with gallium arsenide, comprising the steps of: a. forming a saturated solution of gallium and a charge of gallium arsenide at a saturation temperature higher than the minimum nucleation temperature of gallium arsenide; b. covering a seed of gallium arsenide with the saturated solution while maintaining the seed at a temperature lower than of the solution; c. increasing the temperature of the seed and the saturated solution such that the saturated solution is converted into a nonsaturated solution, thereby allowing a surface part of the seed to be dissolved in the nonsaturated solution and creating a virgin surface on the seed for subsequent nucleation; d. lowering the temperature of the seed below the temperature of the top of the nonsaturated solution to create a temperature gradient from the top of the nonsaturated solution to the seed, lowering the temperature of the seed and the nonsaturated solution substantially equally at a predetermined rate to convert the nonsaturated solution into a saturated solution, and adding arsenic to the saturated solution from a source of arsenic for maintaining saturation of the saturated solution during the subsequent nucleation, the gradient and the equal rate of decline of the seed temperature and the solution temperature causing substantially uniform nucleation of gallium arsenide on the virgin surface of the seed; and e. stabilizing the seed temperature and the solution temperature and maintaining the gradient and the stabilized temperatures during formation of the single crystal while maintaining the saturation of the saturated solution.

Claim 4

A process for growing single crystal semiconductor gallium arsenide in an open tube and in an atmosphere of a gas which is non-reactive with gallium arsenide, comprising the steps of: a. forming a saturated solution of gallium and a charge of gallium arsenide at a saturation temperature higher than the minimum nucleation temperature of gallium arsenide; b. covering a seed of gallium arsenide with the saturated solution while maintaining the seed at a temperature lower than of the solution; c. increasing the temperature of the seed and the saturated solution such that the saturated solution is converted into a nonsaturated solution, thereby allowing a surface part of the seed to be dissolved in the nonsaturated solution and creating a virgin surface on the seed for subsequent nucleation; d. lowering the temperature of the seed below the temperature of the top of the nonsaturated solution to create a temperature gradient from the top of the nonsaturated solution to the seed, lowering the temperature of the seed and the nonsaturated solution substantially equally at a predetermined rate to convert the nonsaturated solution into a saturated solution, and adding arsenic to the saturated solution from a source of arsenic for maintaining saturation of the saturated solution during the subsequent nucleation, the gradient and the equal rate of decline of the seed temperature and the solution temperature causing substantially uniform nucleation of gallium arsenide on the virgin surface of the seed; and e. stabilizing the seed temperature and the solution temperature and maintaining the gradient and the stabilized temperatures during formation of the single crystal while maintaining the saturation of the saturated solution.

Claim 5

The process claimed in claim 1 wherein said step of forming the saturated solution further comprises the step of dissolving crystals of the gallium arsenide in the gallium solvent, the solvent having a lower melting point than the gallium arsenide.

Claim 6

increasing thereafter the temperature of the seed and the saturated solution to a third temperature to convert the saturated solution into a nonsaturated solution to permit the surface layer to dissolve into the nonsaturated solution; B. depositing gallium arsenide on the virgin surface by lowering the temperature of the seed below the minimum nucleation temperature of gallium arsenide to commence deposition of gallium arsenide on the seed while establishing a decreasing temperature gradient of the solution from the third temperature to the minimum nucleation temperature at the seed; C. stabilizing the temperature of the seed and the saturated solution at an isothermal temperature to continue the deposition of gallium arsenide to uniform growth; and D. providing sources of gallium arsenide and arsenic for replenishment of the solution during said temperature lowering and stabilization steps.

Claim 7

increasing thereafter the temperature of the seed and the saturated solution to a third temperature to convert the saturated solution into a nonsaturated solution to permit the surface layer to dissolve into the nonsaturated solution; B. depositing gallium arsenide on the virgin surface by lowering the temperature of the seed below the minimum nucleation temperature of gallium arsenide to commence deposition of gallium arsenide on the seed while establishing a decreasing temperature gradient of the solution from the third temperature to the minimum nucleation temperature at the seed; C. stabilizing the temperature of the seed and the saturated solution at an isothermal temperature to continue the deposition of gallium arsenide to uniform growth; and D. providing sources of gallium arsenide and arsenic for replenishment of the solution during said temperature lowering and stabilization steps.

Claim 8

The process claimed in claim 1 wherein said step of forming the saturated solution further comprises the steps of liquefying the gallium solvent and then causing vaporized arsenic from the arsenic source to react with part of the liquefied gallium solvent to form gallium arsenide, the remainder of the gallium solvent dissolving the gallium arsenide until the saturated solution results.

Claim 9

A process for growing single crystal gallium arsenide in an open tube and in an atmosphere of a gas which is non-reactive with gallium arsenide, comprising the steps of: A. removing a surface layer from a seed of gallium arsenide to provide a virgin surface on the seed, said removing step comprising the steps of:

Claim 10

A process for growing single crystal gallium arsenide in an open tube and in an atmosphere of a gas which is non-reactive with gallium arsenide, comprising the steps of: A. removing a surface layer from a seed of gallium arsenide to provide a virgin surface on the seed, said removing step comprising the steps of:

Claim 11

The process claimed in claim 4 wherein the third temperature is at least 675* C and wherein the temperature gradient is at most 10 centigrade degrees.

Claim 12

The process claimed in claim 4 wherein the third temperature is between 700* and 1,240* C and wherein the temperature gradient is between 1 and 5 centigrade degrees.