Charge transfer dynamics in an electron-hole bilayer device: capacitance oscillations and hysteretic behavior

The capacitance and differential conductance of MBE-grown AlGaAs/GaAs p-i-n diodes are investigated. In these devices, the p-doped layer, an adjacent intrinsic spacer, and a central barrier are composed of AlGaAs. A voltage bias applied between the doped layers enables the accumulation of two-dimensional electrons and holes at the barrier, forming a closely spaced electron-hole bilayer (EHB) system. Surprisingly, the details of the doping scheme have a profound effect on the characteristics of the EHB. In particular, with the dopants placed in a layer with a larger band gap, large conductance and capacitance oscillations are observed, making the observation of excitonic effects virtually impossible. In this article, we report new experiments and analyses that clarify not only the origins but also the quantitative details of the oscillations.