CHARGE ACCUMULATION, IN GAAS ALGAAS TRIPLE BARRIER RESONANT-TUNNELINGSTRUCTURES/

In this article we present photoluminescence and photoluminescence exc itation spectroscopy data from three triple barrier resonant tunneling structures. The spectroscopic techniques are used to estimate the cha rge accumulation in both tunneling quantum wells of the devices as a f unction of bias. The charging behavior is extremely asymmetrical, with significant charge accumulation only in the quantum well adjacent to the emitter region of the device and not in the quantum well adjacent to the collector region, irrespective of the direction of bias. This a symmetry in the charging behavior is analogous to highly asymmetrical double barrier resonant tunneling structures. However, due to the two quantum wells present in the triple barrier design it provides a more flexible system to study charge density dependent effects. We also pre sent evidence for negatively charged exciton formation in the first qu antum well for both directions of applied bias. (C) 1998 American Inst itute of Physics. [S0021-8979(98)04502-2].