Combining steady-state photo-capacitance spectra with first-principles calculations: the case of Fe and Ti in β-Ga2O3

• Published in: New journal of physics Vol. 22; no. 6; pp. 063033 - 63048
• Main Authors: Zimmermann, C, Kalmann Frodason, Y, Rønning, V, Varley, J B, Vines, L
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01-06-2020
• Subjects: Computer simulation; Deep level transient spectroscopy; Defects; defects in semiconductors; First principles; first-principles calculations; Gallium oxides; Iron; Levels; MATERIALS SCIENCE; Mathematical analysis; Photocapacitance; Physics; Spectra; Spectrum analysis; Steady state; steady-state photo-capacitance; Titanium; wide band gap semiconductors; β-Ga; β-Ga2O3
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/ab8e5b

In this study, we demonstrate an approach to identify defects in wide band gap semiconductors by comparing accumulatively-recorded derivative steady-state photo-capacitance (SSPC) spectra to simulations using results from first-principles calculations. Specifically, we present a method to simulate SSPC spectra which adopts inputs both from first-principles calculations and the experimental conditions. The applicability of the developed method is demonstrated using the cases of subsitutional Fe (FeGa) and Ti (TiGa) defects in β-Ga2O3. Using deep-level transient spectroscopy, we identify defect levels associated with FeGaI0/− (EA = 0.66 eV), FeGaII0/− (EA = 0.79 eV) and TiGaII+/0 (EA = 1.03 eV) in the β-Ga2O3 samples studied here. Accumulatively-recorded SSPC spectra reveal several defect levels labeled T1EFG-T6EFG with onsets for optical absorption between 1.5 eV and 4.3 eV. The signature T1EFG consists of several overlapping defect signatures, and is identified as being related to FeGaI0/−, FeGaII0/− and TiGaII+/0 by comparing measured and simulated accumulatively-recorded derivative SSPC spectra.