Abstract
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 (EA = 0.66 eV), (EA = 0.79 eV) and (EA = 1.03 eV) in the β-Ga2O3 samples studied here. Accumulatively-recorded SSPC spectra reveal several defect levels labeled – with onsets for optical absorption between 1.5 eV and 4.3 eV. The signature consists of several overlapping defect signatures, and is identified as being related to , and by comparing measured and simulated accumulatively-recorded derivative SSPC spectra.
Highlights
Defects have a pronounced influence on the electrical and optical properties of semiconductors, and are fundamentally important in determining the expected performance of a given semiconductor device
Fe- and Ti-related charge state transition levels which have recently been identified by deep-level transient spectroscopy (DLTS) in β-Ga2O3 [8, 23] are used to verify the validity of our method, and thereby, we identify the corresponding Steady-state photo-capacitance (SSPC) signatures related to FeGaI, FeGaII and TiGaII in β-Ga2O3
We presented a new method to combine SSPC measurements with first-principles calculations which can be used to reveal the identity of optical charge-state transition levels related to defects in wide band gap semiconductors
Summary
Defects have a pronounced influence on the electrical and optical properties of semiconductors, and are fundamentally important in determining the expected performance of a given semiconductor device. Many wide band gap semiconductors, such as monoclinic gallium sesquioxide (β-Ga2O3), have attracted considerable research interest due to promising properties for applications ranging from photo-detectors to power electronics [3,4,5,6]. It is, a particular challenge to study the electronic properties of defect levels in wide band gap semiconductors. This enables a wide range of study designs suitable for identifying extrinsic as well as intrinsic defects
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