Band lineup for a GaInP/GaAs heterojunction measured by a high-gain <i>N</i> <i>p</i> <i>n</i> heterojunction bipolar transistor grown by metalorganic chemical vapor deposition

Abstract

A GaInP(N)/GaAs( p) heterojunction bipolar transistor was fabricated by metalorganic chemical vapor deposition (MOCVD) for the first time. The common-emitter current gain exceeded 200 at a current density around 10 A/cm2 and the offset voltage was as small as 50 mV. Thermionic emission theory indicates that the conduction-band discontinuity (ΔEc) at GaInP/GaAs heterointerface is as small as 30 meV at room temperature and this value was more than 160 meV smaller than 0.19–0.22 eV obtained by the C-V profile method. The band-gap energy for MOCVD-grown GaInP was 60 meV smaller than the intrinsic band-gap energy (1.91 eV), but this value is too small to explain the difference between the present ΔEc value and the previously reported ΔEc value.