Quantum oscillations under photoexcitation involve direct and indirect excitons and quantum photocapacitance in GaAs/AlAs/InAs p-i-n diode

We explore the quantum dynamics at the interface of a single barrier GaAs/AlAs p-i-n device having InAs quantum dots embedded inside AlAs layer. We observe systematic quantum oscillations in photocapacitance measurements when the sample is optically excited at 10 K. Two sharp peaks in the photocapacitance spectra imply the presence of direct and indirect excitons formed inside the InAs quantum dot and at the interface of quantum dot and the triangular GaAs quantum well, respectively. Spectral peak shifts with increasing applied bias complies with the change of energy levels of triangular quantum well due to effective electric field. Presence of two-dimensional electron and hole gases near the GaAs/AlAs interface certainly point towards the involvement of quantum capacitance. In addition, we also discuss how the formation of excitonic dipoles affects such quantum capacitance. Moreover, periodic variation of negative differential resistance in photocurrent oscillations also correlate with photoconductance oscillations. Understanding the quantum dynamics of carriers involving quantum capacitance and negative differential resistance will help us to explain the many-body physics of these interfacial excitons and its applications.