Charge accumulation in GaAs/AlGaAs triple barrier resonant tunneling structures

Abstract

In this article we present photoluminescence and photoluminescence excitation spectroscopy data from three triple barrier resonant tunneling structures. The spectroscopic techniques are used to estimate the charge accumulation in both tunneling quantum wells of the devices as a function 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 asymmetry 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 present evidence for negatively charged exciton formation in the first quantum well for both directions of applied bias.