| 摘要 |
PROBLEM TO BE SOLVED: To improve high-frequency characteristic of a heterojunction bipolar transistor by achieving both the high current amplification rate and low base resistance. SOLUTION: In a carbon-doped AlxGa1-xAs base layer 3 of a heterojunction bipolar transistor, the concentration of carbon-hydrogen bonds is at least 10% that of carbon. The carbon-hydrogen bonds form traps in the base layer 3. When electrons are injected from the emitter, they are captured by the traps in the base layer and thereby are stabilized. The traps which capture the electrons suppress the recombination current caused by traps characteristic of the material, realizing a high-current amplification rate. Moreover, by including a heat treatment process in the formation of an element, hydrogen is released and emitted from the carbon-hydrogen bonds in an outside base layer 6, which increases the density of carriers in the outside base layer 6 and thereby realizes a low base resistance.
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