Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures Processing Measurement and Phenomena · 1994 · 19 citations · 0 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsDopingIii-v SemiconductorsRare-earth-doped MaterialsSemiconductor Device MaterialsSemiconductor HeterostructuresSemiconductor PhysicsCurrent GainDoped SemiconductorsDoping Effects On Device PerformanceHeterojunction Bipolar TransistorsHole TransportMolecular Beam EpitaxySemiconductor DopingSubstrate Temperature Effects
Carbon tetrabromide was used to dope (In,Ga)As layers lattice matched to InP grown by solid-source molecular beam epitaxy. The maximum hole density depended on substrate temperature. A hole concentration as high as 7.5×1019 cm−3 was achieved at a substrate temperature of 450 °C with reduced As2 flux. Variations in arsenic flux intensity were found to have little effect on the doping density. Hole mobility was comparable to the mobility of Be-doped material grown in our MBE system and to the mobility of CCl4-doped material grown elsewhere. We observed a short-term doping memory effect which we attribute to desorption of CBr4 from growth chamber internal surfaces due to radiant heat from column III ovens. (In,Al)As/(In,Ga)As Npn heterojunction bipolar transistors fabricated using CBr4 doping for the (In,Ga)As base layer with p=2×1019 cm−3 exhibited a dc current gain of eight.