US3870575A — Fabricating a gallium phosphide device

Claim 1

Independent Claim 94 words

A METHOD OF FABRICATING A GALLIUM PHOSPHIDE DEVICE COMPRISING THE STEPS OF: A. PROVIDING A SUBSTRATE OF N-TYPE GALLIUM PHOSPHIDE, B. FORMING A MELT OF GALLIUM-GALLIUM PHOSPHIDE SOLUTION INCLUDING A P-TYPE IMPURITY, SAID IMPURITY HAVING A CONCENTRATION THAT MAINTAINS APPROXIMATELY EQUILIBRIUM WITH THAT OF THE AMBIENT VAPOR PHASE, AND C. GROWING A P-TYPE EPITAXIAL LAYER ON SAID SUBSTRATE FROM SAID MELT, SAID IMPURITY CONCENTRATION THEREIN BEING NOT MORE THAN ND/2.486 K X 10**20 MOL % WHEREIN ND (CM-3) IS THE CARRIER CONCENTRATION IN SAID SUBSTRATE AND K IS A DISTRIBUTION COEFFICIENT OF SAID IMPURITY.

Claim 2

Independent Claim 94 words

A METHOD OF FABRICATING A GALLIUM PHOSPHIDE DEVICE COMPRISING THE STEPS OF: A. PROVIDING A SUBSTRATE OF N-TYPE GALLIUM PHOSPHIDE, B. FORMING A MELT OF GALLIUM-GALLIUM PHOSPHIDE SOLUTION INCLUDING A P-TYPE IMPURITY, SAID IMPURITY HAVING A CONCENTRATION THAT MAINTAINS APPROXIMATELY EQUILIBRIUM WITH THAT OF THE AMBIENT VAPOR PHASE, AND C. GROWING A P-TYPE EPITAXIAL LAYER ON SAID SUBSTRATE FROM SAID MELT, SAID IMPURITY CONCENTRATION THEREIN BEING NOT MORE THAN ND/2.486 K X 10**20 MOL % WHEREIN ND (CM-3) IS THE CARRIER CONCENTRATION IN SAID SUBSTRATE AND K IS A DISTRIBUTION COEFFICIENT OF SAID IMPURITY.

Claim 3

Independent Claim 96 words

A method of fabricating a gallium phosphide device comprising the steps of: a. providing a substrate of N-type gallium phosphide; b. forming a melt of gallium-gallium phosphide solution including a P-type impurity, said impurity having a concentration that maintains approximately equilibrium with that of the ambient vapor phase; and c. growing a P-type epitaxial layer on said substrate from said melt, said impurity concentration therein being not more than nd/2.486 k X 10 20 mol % wherein nd (cm 3) is the carrier concentration in said substrate and k is a distribution coefficient of said impurity.

Claim 4

Independent Claim 96 words

A method of fabricating a gallium phosphide device comprising the steps of: a. providing a substrate of N-type gallium phosphide; b. forming a melt of gallium-gallium phosphide solution including a P-type impurity, said impurity having a concentration that maintains approximately equilibrium with that of the ambient vapor phase; and c. growing a P-type epitaxial layer on said substrate from said melt, said impurity concentration therein being not more than nd/2.486 k X 10 20 mol % wherein nd (cm 3) is the carrier concentration in said substrate and k is a distribution coefficient of said impurity.

Claim 5

Dependent Claim 16 words

A method in accordance with claim 1, wherein said substrate contains tellurium as an N-type impurity.

Claim 6

Dependent Claim 13 words

A method in accordance with claim 1, wherein said melt also contains oxygen.

Claim 7

Dependent Claim 15 words

A method in accordance with claim 3, wherein said oxygen is supplied from gallium trioxide.

Claim 8

Dependent Claim 28 words

A method in accordance with claim 3, wherein said impurity is selected from the group consisting of zinc and cadmium to form a recombination center with said oxygen.

Claim 9

Dependent Claim 18 words

A method in accordance with claim 1, wherein said melt further contains nitrogen to form a recombination center.

Claim 10

Dependent Claim 30 words

A method in accordance with claim 1, wherein a P-N junction is formed substantially between said substrate and said epitaxial layer so that a recombination center exists near said junction.

Claim 11

Independent Claim 211 words

A method of fabricating a gallium phosphide device in a heating furnace through which a quartz tube extends which comprises: a. causing a carrier gas to flow as a stream through said tube from one end to the other; b. placing a boat within said tube; c. placing an N-type gallium phosphide substrate in said boat at the downstream end thereoF; d. placing a melt of gallium-gallium phosphide having gallium trioxide therein in the upstream end of said boat; e. vaporizing zinc into said carrier gas upstream of the boat; f. maintaining the temperature of the melt at a point where the zinc vapor is dissolved in the melt in such an amount that the partial pressure of zinc in the melt reaches equilibrium with the vapor pressure of zinc in the carrier gas, an amount of zinc therein in the equilibrium state being selected equal to or lower than nd/2.486 k X 10 20 mol %, wherein nd (cm 3) is the concentration of the N-type impurity in the substrate and k is a distribution coefficient of said zinc; and g. thereafter causing the melt containing acceptor impurity of zinc and donor impurity of deep level oxygen to overflow the gallium phosphide substrate to form an epitaxial growth layer thereon.

Claim 12

Independent Claim 211 words

A method of fabricating a gallium phosphide device in a heating furnace through which a quartz tube extends which comprises: a. causing a carrier gas to flow as a stream through said tube from one end to the other; b. placing a boat within said tube; c. placing an N-type gallium phosphide substrate in said boat at the downstream end thereoF; d. placing a melt of gallium-gallium phosphide having gallium trioxide therein in the upstream end of said boat; e. vaporizing zinc into said carrier gas upstream of the boat; f. maintaining the temperature of the melt at a point where the zinc vapor is dissolved in the melt in such an amount that the partial pressure of zinc in the melt reaches equilibrium with the vapor pressure of zinc in the carrier gas, an amount of zinc therein in the equilibrium state being selected equal to or lower than nd/2.486 k X 10 20 mol %, wherein nd (cm 3) is the concentration of the N-type impurity in the substrate and k is a distribution coefficient of said zinc; and g. thereafter causing the melt containing acceptor impurity of zinc and donor impurity of deep level oxygen to overflow the gallium phosphide substrate to form an epitaxial growth layer thereon.

Claim 13

Dependent Claim 30 words

A method in accordance with claim 8, wherein the furnace maintains the melt at a temperature between 1,050*C. and 1,150*C. at the time it is caused to overflow the substrate.

Claim 14

Dependent Claim 29 words

A method in accordance with claim 8, wherein the furnace maintains the melt at a temperature of approximately 1,100*C. at the time it is caused to overflow the substrate.

Claim 15

Dependent Claim 39 words

A method in accordance with claim 9, wherein the temperature of the furnace in the region of said substrate is maintained at approximately 950*C. before the coating step and wherein the zinc is vaporized at approximately 500*C. to 570*C.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-03-10	1978-09-09	1979-03-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-03-10	1982-09-09	1983-03-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-03-10	1986-09-09	1987-03-11	$7700.00	Window Closed / Lapsed

Fabricating a gallium phosphide device

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