Contactless electroreflectance characterization of GaInP/GaAs heterojunction bipolar transistor structures

We have characterized two GaInP/GaAs (001) heterojunction bipolar transistor structures, fabricated by organometallic chemical vapor deposition and chemical beam epitaxy, using contactless electroreflectance, including the dependence of the signals on the polarization {[110] and [11̄0]} of the incident radiation. The ordering parameters deduced from the polarization dependence of the GaInP emitter signals are consistent with transmission electron microscope measurements. From the observed Franz–Keldysh oscillations we have evaluated the electric fields in the collector/base and emitter/base regions. In general, these fields are in good agreement with a calculation based on a comprehensive, self-consistent model, including the photovoltaic effect.