Sr. Bahl et Ja. Delalamo, PHYSICS OF BREAKDOWN IN INALAS N(+)-INGAAS HETEROSTRUCTURE FIELD-EFFECT TRANSISTORS/, I.E.E.E. transactions on electron devices, 41(12), 1994, pp. 2268-2275
InAlAs/n(+)-InGaAs HFET's on InP have demonstrated a high breakdown vo
ltage in spite of the narrow bandgap of the InGaAs channel. In order t
o understand this unique feature, we have carried out a systematic tem
perature-dependent study of off-state breakdown. We find that off-stat
e breakdown at room-temperature is drain-gate limited and that the bre
akdown voltage shows a negative temperature coefficient. Based on thes
e and other findings, we propose that off-state breakdown is a two-ste
p process. First, electrons are injected by thermionic-field emission
from the gate to the insulator, Second, electrons enter into the high-
field drain-gate region of the channel hot, and relax their energy thr
ough impact-ionization. This combined mechanism explains,our experimen
tal observations that L off-state breakdown in InAlAs/n(+)-InGaAs HFET
's depends both on channel and insulator design, Our findings are rele
vant to other InAlAs/InGaAs HFET's, such as the MODFET, as well as HFE
T's based on other narrow-bandgap materials.