Dg. Austing et al., THE PRESSURE-DEPENDENCE OF THE TUNNELING CURRENT IN SINGLE-BARRIER ALAS GAAS STRUCTURES/, Semiconductor science and technology, 10(5), 1995, pp. 616-623
The current-voltage (I-V) characteristics at 77 K are presented up to
a pressure of 16 kbar for an AlAs/GaAs single-barrier structure and an
AlAs/GaAs double-barrier structure behaving like a single-barrier str
ucture. The current is first seen to rise with pressure and then fall
at higher pressure close to and beyond the type I to type II transitio
n-a signature for the involvement of the X profile. We present one mod
el to account for this behaviour in both the low-pressure regime and t
he new high-pressure regime. For the latter we stress the importance o
f the pinning of the Fermi level in the contacts by the lowest confine
d X state in the AlAs region, which leads to band bending and the form
ation of depletion barriers in the contacts. Additionally, we contrast
the behaviour of these indirect-gap barrier structures with that of a
direct-gap Al0.36Ga0.64As/GaAs structure over the same pressure range
, and discuss the possible origin of the falling background current in
AlAs/GaAs double-barrier structures displaying X-X interwell and mixe
d X-Gamma resonances in the high-pressure regime.