Low Turn-on Voltage InGaP / GaAsSb / GaAs DHBT Grown by MOCVD
In this work, an InGaP/GaAsSb/GaAs DHBT with carbon doping up to 4E19/cm GaAsSb base was studied. A current gain of 115 at the collector current density of 25KA/cm2 was achieved for the Rbs of about 530ohm/sq. Over 100mV turn-on voltage and knee voltage reduction and 2/3 offset voltage were obtained for the GaAsSb based HBT compared with the standard InGaP/GaAs SHBT. The DC gain of the device is less temperature dependence (the DC gain variation is less than 3% for the temperature range from 25 degree C to 100 degree C.) due to the larger valence band discontinuity between InGaP emitter and GaAsSb base, compare with the standard InGaP/GaAs SHBT. These results indicate that GaAsSb is a great choice for the base material of a low turn-on voltage HBT.
InGaP/GaAsSb/GaAs DHBTs with low turn-on voltage and high current gain
An InGaP/GaAsSb/GaAs double heterojunction bipolar transistor (DHBT) is presented. It features the use of a fully strained pseudomorphic GaAsSb (Sb composition: 10.4%) as the base layer and an InGaP layer as the emitter, which both eliminates the misfit dislocations and increases the valence band discontinuity at the InGaP/GaAsSb interface. A current gain of 200 has been obtained from the InGaP/GaAsSb/GaAs DHBT, which is the highest value obtained from GaAsSb base GaAs-based HBTs. The turn-on voltage of the device is typically 0.914 V for the 10.4% Sb composition, which is 0.176 V lower than that of traditional InGaP/GaAs HBT. The results show that GaAsSb is a suitable base material for reducing the turn-on voltage of GaAs HBTs.
A concept of general monotonicity and applications
In this paper we investigate properties of the general monotone sequences and functions, a generalization of monotone sequences and functions as well as of those of bounded variation. Some applications to various problems of analysis are given. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim