SEMICONDUCTOR MATERIAL HAVING BIPOLAR TRANSISTOR STRUCTURE AND SEMICONDUCTOR DEVICE USING SAME

摘要

An epitaxial substrate (20) having a collector layer (22), a base layer (23) and an emitter layer (24) formed on a semi-insulating GaAs substrate (21) further comprises a hole blocking layer (22C) which is formed in the collector layer (22) for preventing flow-in of holes from the base layer (23). With this structure, a collector current flow is suppressed when the electron speed is saturated due to a rise in the collector current density, thereby preventing a thermal runaway of the collector current without using a ballast resistor or the like. The thermal runaway of the collector current can be also prevented by providing an additional layer (2C) in the collector layer (2) so that an electron barrier is formed in a conduction band with electrons accumulated due to a rise in the collector current density.