Direct measurement of the density and energy level of compensating acceptors and their impact on the conductivity of n-type Ga2O3 films

Abstract

Intrinsic and extrinsic point defects often act as electron traps in oxide-based semiconductors and significantly impact their electrical and optical properties. Here, we show how to measure the density, energy level, and trapping cross section of the compensating acceptors that act as electron traps in Ga2O3 films, and we introduce the sheet trap number or the sheet compensating acceptor number as an essential parameter to fully describe the electrical transport properties of semiconductors. Si-doped β-Ga2O3 thin films were fabricated homoepitaxially by metalorganic chemical vapor deposition and studied by thermally stimulated luminescence spectroscopy, temperature dependent Hall-effect measurements, and secondary ion mass spectroscopy to investigate the compensating acceptor defects responsible for suppressing conductivity in the films. A deep level defect of energy in the range of 0.50–0.65 eV was identified as a compensating acceptor. The correlation between the electrical properties and its concentration and characteristics was established. This work shows how to quantify the density of compensating acceptors in semiconductors and directly relate it to the electrical transport properties, which should significantly advance the development of semiconductors and devices.