InGaP/GaAs Heterojunction Bipolar Transistors with an Ultra-High Carbon-Doped Base (p=1.5×1021cm-3)

Abstract

In0.5Ga0.5P/GaAs heterojunction bipolar transistors (HBTs) having a heavily carbon (C)-doped GaAs base with an ultra-high hole concentration of 1.5×1021 cm-3 were successfully fabricated by metalorganic molecular beam epitaxy (MOMBE) for the first time. Tertiarybutylphosphine (TBP), elemental In and elemental Ga were used as source materials for the growth of In0.5Ga0.5P emitter and trimethylgallium (TMG) and elemental arsenic ( As4) for the growth of GaAs base. Abrupt change of composition was obtained at the heterointerface between InGaP emitter and heavily C-doped GaAs base, suggesting no defect formation due to heavy doping in the base. Small signal current gain (h fe) of 16 and DC current gain (h FE) of 12 were obtained for devices with a base thickness of 15 nm despite the ultra-high doping in the base layer. To our knowledge, this is the first report on the InGaP/GaAs HBTs with an ultra-high C-doped base layer.