Vertical transport and electroluminescence in InAs/GaSb/InAs structures: GaSb thickness and hydrostatic pressure studies

We have measured the current-voltage (formula presented) of type-II InAs/GaSb/InAs double heterojunctions (DHET’s) with “GaAs like” interface bonding and GaSb thickness between 0 and 1200 Å. A negative differential resistance (NDR) is observed for all DHET’s with GaSb thickness >60 Å below which a dramatic change in the shape of the (formula presented) and a marked hysteresis is observed in some samples. The temperature dependence of the (formula presented) is found to be very strong below this critical GaSb thickness. The (formula presented) characteristics of selected DHET’s are also presented under hydrostatic pressures up to 11 kbar. Finally, a midinfrared electroluminescence is observed at 1 bar with a threshold at the NDR valley bias. The band profile calculations presented in the analysis are markedly different to those given in the literature and arise due to the positive charge that it is argued will build up in the GaSb layer under bias. We conclude that the dominant conduction mechanism in DHET’s is most likely to arise out of an inelastic electron-heavy-hole interaction similar to that observed in single heterojunctions with “GaAs like” interface bonding, and not out of resonant electron-light-hole tunneling as proposed by Yu et al. A Zener tunneling mechanism is shown to contribute to the background current beyond NDR.