| 摘要 |
PURPOSE: A double hetero-junction bipolar transistor(DHBT) having a ballistic collector structure is provided to increase a breakdown voltage thereof. CONSTITUTION: The transistor includes a GaAs sub-collector layer formed on a semiconductor substrate, an InGaP collector layer, an Al(x)Ga(1-x)As grading layer(14), the first GaAs spacer layer, a GaAs base layer, the second GaAs spacer layer, an InGaP or AlGaAs emitter layer, and a GaAs emitter cap layer. In particular, the InGaP collector layer is composed of the first n- collector layer formed on the GaAs sub-collector layer, the first n+ collector layer(16) formed on the first n- collector layer, a p+ collector layer(15) formed on the first n+ collector layer(16), and the second n- collector layer formed on the p+ collector layer(15). Preferably, the first and second n- collector layers may have an n-type impurity concentration of about 5x10¬16/cm¬3, while the first n+ collector layer(16) and the p+ collector layer(15) may have an impurity concentration of about 5x10¬18/cm¬3. In addition, the Al(x)Ga(1-x)As grading layer(14) may have an n-type impurity concentration of about 5x10¬16/cm¬3.
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