Preparation process of compound semiconductor
First Claim
1. A process for preparing compound semiconductor thin films in which an organometallic compound cotaining an element of Group III or II and a hydride containing an element of Group V or VI are transported over a heated substrate and are subjected to thermal decomposition, whereby a III-V or 11-VI compound semiconductor is grown over said heated substrate, the process comprising:
- repeating a cycle consisting of the following steps, whereby a III-V or II-VI compound semiconductor is grown over said heated substrate by forming alternating layers of an element of Group III or II and an element of Group V or VI, respectively;
(a) introducing over said heated substrate a carrier gas comprising a hydride containing an element of Group V or VI and present in a first concentration, said carrier gas further comprising at least one organometallic compound containing an element of Group III or II and present in a concentration, to thermally decompose the organometallic compound and form a layer of at least one element of Group III or II, wherein said first concentration of said hydride is a molar fraction ranging from a value which corresponds to the equilibrium molar fraction of said element of Group V or VI on said III-V or II-VI compound semiconductor at the temperature of said heated substrate up to a value at which said element of Group V or VI is not substantially incorporated into said layer of at least one element of Group III or II;
(b) interrupting the introduction of said organometallic compound;
(c) introducing over said heated substrate a carrier gas comprising a hydride containing an element of Group V or VI and present in a second concentration, which second concentration is higher in hydride than said first concentration, to thermally decompose the hydride and form a layer of an element of Group V or VI on top of said layer of an element of Group III or II; and
(d) interrupting the introduction of said hydride at said second concentration.
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Accused Products
Abstract
A compound semiconductor thin film is formed by growing a plurality of molecular layers one over another. According to the present invention, while a carrier gas and a small quantity of hydride containing an element in Group V or VI are normally flowed, an organometallic compound which is diluted with hydrogen and which contains an element in Group III or II and a hydride which is diluted with hydrogen and which contains an element in Group V or VI are alternately introduced over a substrate so that an atomic layer of an element in Group III or II and an atomic layer of an element in Group V or VI are alternately grown over the substrate. According to this method, grown layers having a high degree of purity can be obtained. A portion such as a Ga-Ga two-layer structure formed in the growth of a surface of an element in Group III or II can easily be eliminated by the introduction of a hydrogen halide so that the surface defects and deep levels are significantly decreased and perfect crystals can be obtained. According to the present invention, a high-concentration doping of a III-V compound semiconductor becomes possible. The method of the present invention is advantageous in the fabrication of high-speed FETs and multi-quantum-well lasers using compound semiconductors.
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Citations
26 Claims
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1. A process for preparing compound semiconductor thin films in which an organometallic compound cotaining an element of Group III or II and a hydride containing an element of Group V or VI are transported over a heated substrate and are subjected to thermal decomposition, whereby a III-V or 11-VI compound semiconductor is grown over said heated substrate, the process comprising:
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repeating a cycle consisting of the following steps, whereby a III-V or II-VI compound semiconductor is grown over said heated substrate by forming alternating layers of an element of Group III or II and an element of Group V or VI, respectively; (a) introducing over said heated substrate a carrier gas comprising a hydride containing an element of Group V or VI and present in a first concentration, said carrier gas further comprising at least one organometallic compound containing an element of Group III or II and present in a concentration, to thermally decompose the organometallic compound and form a layer of at least one element of Group III or II, wherein said first concentration of said hydride is a molar fraction ranging from a value which corresponds to the equilibrium molar fraction of said element of Group V or VI on said III-V or II-VI compound semiconductor at the temperature of said heated substrate up to a value at which said element of Group V or VI is not substantially incorporated into said layer of at least one element of Group III or II; (b) interrupting the introduction of said organometallic compound; (c) introducing over said heated substrate a carrier gas comprising a hydride containing an element of Group V or VI and present in a second concentration, which second concentration is higher in hydride than said first concentration, to thermally decompose the hydride and form a layer of an element of Group V or VI on top of said layer of an element of Group III or II; and (d) interrupting the introduction of said hydride at said second concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for preparing compound semiconductor thin films in which an organometallic compound containing an element of Group III or II and a hydride containing an element of Group V or VI are introduced over a heated substrate and are subjected to thermal decomposition, whereby a III-V or II-VI compound semiconductor is grown over said heated substrate, the process comprising:
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repeating a cycle consisting of the following steps, whereby a III-V or II-VI compound semiconductor is grown over said heated substrate by forming alternating layers of an element of Group III or II and an element of Group V or VI, respectively; (a) introducing over said heated substrate a first carrier gas comprising a hydride containing an element of Group V or VI and present in a first concentration, said first carrier gas further comprising at least one organometalIic compound containing an element of Group III or II and present in a concentration, to thermally decompose the organometallic compound and form a layer of at least one element of Group III or II, wherein said first concentration of said hydride is a molar fraction ranging from a value which corresponds to the equilibrium molar fraction of said element of Group V or VI on said III-V or II-VI compound semiconductor at the temperature of said heated substrate up to a value at which said element of Group V or VI is not substantially incorporated into said layer of at least one element of Group III or II; (b) interrupting the introduction of said organometallic compound; and (c) introducing over said heated substrate a second carrier gas comprising a hydride containing an element of Group V or VI and present in a second concentration, which second concentration is higher in hydride than said first concentration, to thermally decompose the hydride and form a layer of an element of Group V or VI on top of said layer of at least one element of Group III or II; and (d) interrupting the introduction of said hydride at said second concentration; and (e) introducing over said heated substrate a third carrier gas comprising a hydrogen halide and present in halide which is diluted by a third carrier gas to a concentration of said hydrogen halide. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A process for preparing compound semiconductor thin films, comprising:
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repeating a cycle consisting of the following steps, whereby a compound semiconductor which is an arsenide of a Group III or II element is grown over said heated substrate by forming alternating layers of at least one element of Group III or II and arsenic, respectively; (a) introducing over said heated substrate a carrier gas comprising hydrogen and arsine (AsH3) present in a first concentration, said carrier gas further comprising at least one organometallic compound containig an element of Group III or II and present in a concentration, to thermally decompose the organometallic compound and form a layer of at least one of Group III or II, wherein said first concentration of arsine is a molar fraction ranging from a value which corresponds to the equilibrium molar fraction of arsenic on said III-V or II-VI compound semiconductor at the temperature of said heated substrate up to a value at which said arsenic is not substantially incorporated into said layer of at least one element of Group III or II; (b) interrupting the introduction of said organometallic compound; (c) introducing said heated substrate a carrier gas comprising hydrogen and arsine (AsH3) and present in a second concentration, which second concentration is higher in arsine (AsH3) than said first concentration, to thermally decompose the arsine (AsH3) and form a layer of arsenic on top of said layer of at least one element of Group III or II; and introducing in any of steps (a) through (c), of said cycle silane (SiH4), thereby doping said III-V or II-VI compound semiconductor.
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20. A process for preparing compound semiconductor thin films, comprising:
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repeating a cycle consisting of the following steps, whereby a III-V compound semiconductor is grown over said heated substrate by forming alternating layers of an element of Group III and an element of Group V, respectively; (a) introducing over said heated substrate a carrier gas comprising hydrogen and a hydride containing an element of Group V and present in a first concentration, said carrier gas further comprising at least one organometallic compound containing an element of Group III and present in a concentration, to thermally decompose the organometallic compound and form a layer of at least one element of Group III, wherein said first concentration of said hydride is a molar fraction ranging from a value which corresponds to the equilibrium molar fraction of said element of Group V on said III-V compound semiconductor at the temperature of said heated substrate up to a value at which said element of Group V is not substantially incorporated into said layer of at least one element of Group III; (b) interrupting the introduction of said organometallic compound; (c) introducing on said heated substrate a carrier gas comprising hydrogen and a hydride containing an element of Group V and present in a second concentration, which second concentration is higher in hydride than said first concentration, to thermally decompose the hydride and form a layer of an element of Group V on top of said layer of at least one element of Group III; (d) interrupting the introduction of said hydride at said second concentration; (e) introducing over said heated substrate a hydrogen halide which is diluted by said hydrogen carrier gas; (f) interrupting the introduction of said hydrogen halide; and (g) introducing over said heated substrate said carrier gas comprising hydrogen together with a compound containing an element in Group IV, VI or II, thereby doping said III-V compound semiconductor. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification