| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that the lower current becomes, the smaller current gain becomes in a region with a low collector current. SOLUTION: By an electron supply layer 23, the generation of a recombination current via an electron-capturing center is inhibited for improving a current gain. Layer structure includes an n-type GaAs collector electrode layer 5 where 5×1018 cm-3 Si is doped on a GaAs substrate 6, an undoped GaAs collector layer 4, a p-type GaAs base layer 3 where 4×1019 cm-3 C is doped, a second emitter layer 22 of an n-type InGaP emitter layer 2 where 3×1017 cm-3 Si is doped, a first emitter layer 21 of an n-type GaAs where 3×1017 cm-3 Si is doped, an emitter electrode layer 1 of an n-type InGaAs where 2×1019 cm-3 Si is doped, and an electron supply layer 23 that is provided on the interface between the first and second emitter layers 21 and 22. Electron concentration that is supplied from the electron supply layer 23 is Si doping concentration and layer thickness where a sheet concentration of 1×1012 cm-2 is achieved.
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