Dc. Wang et al., CURRENT CONDUCTION IN QUANTUM-WELL INFRARED PHOTODETECTORS UNDER LOW-BIAS OPERATION, Applied physics letters, 68(18), 1996, pp. 2532-2534
Device operation under low applied bias voltage has been examined for
both p-type and n-type quantum well infrared photodetectors. Under low
electric fields and at low temperatures, the carrier lifetime in the
quantum well bound states is large compared to the intrawell carrier s
cattering time, allowing the carriers to thermalize in the heavily dop
ed quantum wells. This thermalization process partially or fully decou
ples the statistical fluctuations in carrier transport through a barri
er region from one section to the next. Therefore, the device can be t
hought of as M statistically independent sections in series, where M i
s equal to the ratio of active device length over the extended state c
arrier trajectory. Based on this concept and the additional assumption
that the charge transport process is emission limited, the dark curre
nt was calculated for four different devices. The excellent agreement
between the measured and calculated dark current-voltage characteristi
cs confirms our model assumptions. (C) 1996 American Institute of Phys
ics.