COMPOUND SEMICONDUCTOR DEVICE AND METHOD OF MAKING THE SAME

The compound semiconductor device comprises a first semiconductor layer to be a sub-collector region of a hetero junction bipolar transistor and substrate of a laser diode, a second semiconductor layer to be a collector region formed on first semiconductor layer, a third semiconductor layer to be a base region formed on the second layer, a fourth semiconductor layer to be an emitter region formed on the third layer, a fifth semiconductor layer to be a cap layer formed on the fourth layer, a T-shaped emitter electrode formed on the fifth layer, a second semiconductor layer to be a clad layer formed on the first layer, a sixth semiconductor layer to be an active layer formed on the second layer, a seventh semiconductor layer to be a clad layer formed on the sixth layer, a eighth semiconductor layer to be a cap layer formed on the seventh layer, an electrode in contact with a predetermined portion of the eighth layer, high resistance region overlapped with second semiconductor layer, and a common electrode on an exposed region between the hetero junction bipolar transistor and laser diode.