Process for producing silicon carbide crystals having increased minority carrier lifetimes
First Claim
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1. A process for producing silicon carbide crystals having increased minority carrier lifetimes, comprising:
- growing at a growth temperature to form a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime;
heating said silicon carbide crystal to a temperature greater than its growth temperature to dissociate at least some of said recombination centers to decrease the concentration thereof; and
thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow to reduce the recombination of said dissociated recombination centers to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime.
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Abstract
A process is described for producing silicon carbide crystals having increased minority carrier lifetimes. The process includes the steps of heating and slowly cooling a silicon carbide crystal having a first concentration of minority carrier recombination centers such that the resultant concentration of minority carrier recombination centers is lower than the first concentration.
17 Citations
45 Claims
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1. A process for producing silicon carbide crystals having increased minority carrier lifetimes, comprising:
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growing at a growth temperature to form a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime; heating said silicon carbide crystal to a temperature greater than its growth temperature to dissociate at least some of said recombination centers to decrease the concentration thereof; and thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow to reduce the recombination of said dissociated recombination centers to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 23, 44, 45)
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13. A process for producing silicon carbide crystals having increased minority carrier lifetimes, comprising:
heating a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime and thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime, wherein the heating and cooling steps comprise heating and cooling a silicon carbide crystal under conditions to provide a silicon carbide crystal exhibiting a minority carrier lifetime of at least about 30 microseconds (μ
s).
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18. A process for the production of a device comprising a silicon carbide crystal exhibiting increased minority carrier lifetime, comprising:
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growing at a growth temperature to form a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime; heating said silicon carbide crystal to a temperature greater than its growth temperature to dissociate at least some of said recombination centers to decrease the concentration thereof; thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow to reduce the recombination of said dissociated recombination centers to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime; and incorporating said silicon carbide crystal into a device. - View Dependent Claims (19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30)
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31. A process for the production of a device comprising a silicon carbide crystal exhibiting increased minority carrier lifetime comprising heating a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime and thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime, wherein the heating and cooling steps comprise heating and cooling a silicon carbide crystal under conditions to provide a silicon carbide crystal exhibiting a minority carrier lifetime of at least about 30microseconds (μ
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incorporating said silicon carbide crystal into a device.
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32. A process for producing silicon carbide crystals having increased minority carrier lifetimes, comprising:
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growing at a growth temperature to form a silicon carbide crystal having a first concentration of minority carrier recombination centers resulting in a first minority carrier lifetime; heating said silicon carbide crystal to a temperature greater than its growth temperature; and thereafter cooling the heated silicon carbide crystal at a rate of about 2°
C. per minute or less to provide a silicon carbide crystal having a second concentration of minority carrier recombination centers that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime. - View Dependent Claims (33, 34, 35, 36, 37)
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38. A process for producing silicon carbide crystals having increased minority carrier lifetimes, comprising:
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growing at a growth temperature to form a silicon carbide crystal having a first concentration of intrinsic defects and a first minority carrier lifetime; heating said silicon carbide crystal to a temperature that decreases the concentration of intrinsic defects; and thereafter cooling the heated silicon carbide crystal at a rate sufficiently slow so that the silicon carbide crystal has a second concentration of intrinsic defects that is lower than the first concentration thereby providing a material having an increased minority carrier lifetime. - View Dependent Claims (39, 40, 41, 42, 43)
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Specification