InGaAs/InP double-heterojunction bipolar transistors with step graded InGaAsP between InGaAs base and InP collector grown by metalorganic chemical vapor deposition

Abstract

We have fabricated InGaAs/InP double-heterojunction bipolar transistors (DHBTs) grown by metalorganic chemical vapor deposition (MOCVD). By inserting step graded InGaAsP layers between p+-InGaAs base and n−-InP collector, the current gain of DHBTs with the graded layers was about twice as large as that without the graded layers, and the dependence of collector current on collector/emitter voltage was smaller than that without graded layers. The current gain was measured up to 2300 with 25×25 μm2 emitter area at a collector current density of 1×104 A/cm2.

GSMBE growth of InGaAsP step-graded composite collector structure applied to DHBT

“…Thereby InP/InGaAs/InP double heterojunction HBT (DHBT) has been attracted much attention for millimeter wave power applications. While the breakdown voltage of InP/InGaAs/InP DHBT benefits from the use of wide band gap collector of InP, the potential barrier at the base-collector (B-C) junction due to the conduction band discontinuity can result in poor device performance [6][7][8]. Many structures on B-C junction design to resolve the problem were proposed, such as with an InGaAs/InP superlattice, with a thin n+-InP insert layer, and with a step-graded InGaAsP composite collector structure [8][9][10][11].…”

InP/InGaAs/InP DHBT structures with graded composition base grown by gas source molecular beam epitaxy

“…InP/InGaAs/InP double heterojunction bipolar transistor (DHBT) can efficiently promote the breakdown voltage due to its wide band gap of InP collector [4]. For DHBTs, however, the potential barrier at the base-collector (B-C) junction due to the conduction band discontinuity can result in current blocking effect, which causes poor device characteristics [4][5][6]. In order to eliminate the barrier, many structures in B-C junction were proposed, such as using InGaAs/InAlAs superlattice structures and inserting a thin undoped InGaAs spacer at the B-C junction [7][8][9][10].…”

Carbon-doped InP∕In0.53Ga0.47As single and double heterojunction bipolar transistors grown by solid-source molecular-beam epitaxy

“…However, due to the large conduction band discontinuity between the InGaAs base and InP collector, InP / InGaAs DHBTs typically suffer from the current blocking effect. So far, various design schemes have been proposed to suppress the current blocking effect, such as those using a composite collector, [9][10][11] pn-pair doping, 12 InGaAsP graded layers, 13 and staggered energy band lineup of a InP / GaAsSb heterojunction. 14 Although the last two approaches are ideal as far as potential barrier due to conduction band discontinuity is concerned, special and complex optimization for the growth conditions is needed to obtain good step-graded InGaAsP or GaAsSb materials.…”