Huang, Chao-HsingChao-HsingHuangLin, Hao-HsiungHao-HsiungLin2009-03-182018-07-062009-03-182018-07-061993https://www.scopus.com/inward/record.uri?eid=2-s2.0-0027656219&doi=10.1016%2f0038-1101%2893%2990158-M&partnerID=40&md5=1f053c01ec84e6bfb548818cf89fc5a4In this study, the characteristics of InAlAs/InGaAs double heterojunction bipolar transistors (DHBT's) with abrupt and graded base-collector junction structures are investigated. We find that because of the large conduction band discontinuity between the InGaAs base and the InAlAs collector, the base-collector abrupt heterojunction notch will accumulate a two-dimensional electron gas (2DEG) and the heterojunction spike will be pushed up. Therefore, poor knee-shape and reach-through effects appear in the device even with a 500 Å-thick undoped InGaAs layer sandwiched between the base and collector. This finding has never been observed in DHBT's with small band discontinuity material systems such as InP/InGaAs and AlGaAs/GaAs. The InAlAs/InGaAs DHBT with a graded base-collector junction shows no knee-shape and reach-through effects, because the heterojunction notch has been smoothed out. © 1993.application/pdf613796 bytesapplication/pdfen-USElectrons; Gases; Heterojunctions; Semiconducting indium compounds; Double heterojunction bipolar transistors; Electron gas; Heterojunction bipolar transistors; Bipolar transistorsjournal article10.1016/0038-1101(93)90158-M2-s2.0-0027656219http://ntur.lib.ntu.edu.tw/bitstream/246246/145997/1/06.pdf