Donor binding energy and thermally activated persistent photoconductivity in high mobility (001) AlAs quantum wells

TL;DR

This study investigates the donor binding energies and thermally activated persistent photoconductivity in high mobility (001) AlAs quantum wells, revealing how illumination and temperature affect electron densities and doping efficiencies.

Contribution

It provides new measurements of donor binding energies and demonstrates the thermal activation behavior of persistent photoconductivity in AlAs quantum wells.

Findings

Deep donor binding energy of 65.2 meV in dark conditions

Persistent photoconductivity saturates after annealing at 30 K

Dark and post-illumination doping efficiencies are quantified

Abstract

A doping series of AlAs (001) quantum wells with Si delta-modulation doping on both sides reveals different dark and post-illumination saturation densities, as well as temperature dependent photoconductivity. The lower dark two-dimensional electron density saturation is explained assuming deep binding energy of Delta_DK = 65.2 meV for Si-donors in the dark. Persistent photoconductivity (PPC) is observed upon illumination, with higher saturation density indicating shallow post-illumination donor binding energy. The photoconductivity is thermally activated, with 4 K illumination requiring post-illumination annealing to T = 30 K to saturate the PPC. Dark and post-illumination doping efficiencies are reported.