Epitaxial wafer for hetero-junction bipolar transistor and hetero-junction bipolar transistor
AssigneeSumitomo Chemical Company, Limited
InventorsTakeshi Meguro, Shinjiro Fujio
Life of this patent
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Abstract
An epitaxial wafer for a heterojunction bipolar transistor and a heterojunction bipolar transistor capable of reducing the resistance of the sub-collector layer without reducing the current amplification factor are provided. In an epitaxial wafer for a heterojunction bipolar transistor including a sub-collector layer made of n-type GaAs, the sub-collector layer contains n-type impurities having a covalent radius that is smaller than the covalent radius of the substitution site and n-type impurities having a covalent radius that is larger than the covalent radius of the substitution site.
Claims4
An epitaxial wafer for a heterojunction bipolar transistor comprising:
- a sub-collector layer made of n-type GaAs, the sub-collector layer containing n-type impurities having a covalent radius that is smaller than the covalent radius of the substitution site and n-type impurities having a covalent radius that is larger than the covalent radius of the substitution site,
- wherein in the sub-collector layer, a sum ((A)+(B)) of a concentration (A) of the n-type impurities having a covalent radius that is smaller than the covalent radius of the substitution site and a concentration (B) of the n-type impurities having a covalent radius that is larger than the covalent radius of the substitution site is equal to or greater than 3×1018 cm−3 and equal to or less than 1×1019 cm−3.
A heterojunction bipolar transistor comprising:
- a sub-collector layer made of n-type GaAs, the sub-collector layer containing n-type impurities having a covalent radius that is smaller than the covalent radius of the substitution site and n-type impurities having a covalent radius that is larger than the covalent radius of the substitution site,
- wherein in the sub-collector layer, a sum ((A)+(B)) of a concentration (A) of the n-type impurities having a covalent radius that is smaller than the covalent radius of the substitution site and a concentration (B) of the n-type impurities having a covalent radius that is larger than the covalent radius of the substitution site is equal to or greater than 3×1018 cm−3 and equal to or less than 1×1019 cm−3.
Dependencies are inferred from the claim text.