Z. Othaman et al., UNAMBIGUOUS IDENTIFICATION OF X-POINT-RELATED RESONANCES IN GAAS ALAS/GAAS TUNNEL-DIODES UNDER HYDROSTATIC-PRESSURE/, Semiconductor science and technology, 8(7), 1993, pp. 1483-1486
We have performed detailed investigations of an asymmetrically doped G
aAs/AlAs/GaAs tunnel diode in which a 2D accumulation layer forms at t
he emitter/barrier interface under forward bias. The systematic applic
ation of hydrostatic pressure at 77 K leads to the development of a we
ll resolved peak in dl/dV in forward bias above 2 kbar. The peak shift
s approximately linearly downwards in voltage as the pressure is incre
ased in constant steps. Comparison with self-consistent theoretical ca
lculations enables us to unambiguously identify the peak as arising fr
om resonant tunnelling between the electron states in the accumulation
layer and the longitudinal X-point subbands of the AlAs barrier. To o
ur knowledge this is the first time that quantitative agreement betwee
n theory and experiment has been achieved and places our interpretatio
n beyond question. Our conclusions have important implications for the
optimization of microwave diodes based on such structures.