Band lineup for a GaInP/GaAs heterojunction measured by a high‐gain Npn heterojunction bipolar transistor grown by metalorganic chemical vapor deposition

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.