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

## 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 $${\mathrm{Fe}}_{\text{GaI}}^{0/-}$$ (E A = 0.66 eV), $${\mathrm{Fe}}_{\text{GaII}}^{0/-}$$ (E A = 0.79 eV) and $${\mathrm{Ti}}_{\text{GaII}}^{+/\mathrm{0}}$$ (E A = 1.03 eV) in the β-Ga2O3 samples studied here. Accumulatively-recorded SSPC spectra reveal several defect levels labeled $${T}_{\mathrm{1}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$$–$${T}_{\mathrm{6}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$$ with onsets for optical absorption between 1.5 eV and 4.3 eV. The signature $${T}_{\mathrm{1}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$$ consists of several overlapping defect signatures, and is identified as being related to $${\mathrm{Fe}}_{\text{GaI}}^{0/-}$$, $${\mathrm{Fe}}_{\text{GaII}}^{0/-}$$ and $${\mathrm{Ti}}_{\text{GaII}}^{+/\mathrm{0}}$$ by comparing measured and simulated accumulatively-recorded derivative SSPC spectra.

- Authors:

- Publication Date:

- Research Org.:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office; Research Council of Norway

- OSTI Identifier:
- 1634857

- Alternate Identifier(s):
- OSTI ID: 1668493

- Report Number(s):
- LLNL-JRNL-806785

Journal ID: ISSN 1367-2630

- Grant/Contract Number:
- AC52-07NA27344; 251131

- Resource Type:
- Published Article

- Journal Name:
- New Journal of Physics

- Additional Journal Information:
- Journal Name: New Journal of Physics Journal Volume: 22 Journal Issue: 6; Journal ID: ISSN 1367-2630

- Publisher:
- IOP Publishing

- Country of Publication:
- United Kingdom

- Language:
- English

### Citation Formats

```
Zimmermann, C., Kalmann Frodason, Y., Rønning, V., Varley, J. B., and Vines, L. Combining steady-state photo-capacitance spectra with first-principles calculations: the case of Fe and Ti in β-Ga2O3. United Kingdom: N. p., 2020.
Web. doi:10.1088/1367-2630/ab8e5b.
```

```
Zimmermann, C., Kalmann Frodason, Y., Rønning, V., Varley, J. B., & Vines, L. Combining steady-state photo-capacitance spectra with first-principles calculations: the case of Fe and Ti in β-Ga2O3. United Kingdom. doi:10.1088/1367-2630/ab8e5b.
```

```
Zimmermann, C., Kalmann Frodason, Y., Rønning, V., Varley, J. B., and Vines, L. Wed .
"Combining steady-state photo-capacitance spectra with first-principles calculations: the case of Fe and Ti in β-Ga2O3". United Kingdom. doi:10.1088/1367-2630/ab8e5b.
```

```
@article{osti_1634857,
```

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

author = {Zimmermann, C. and Kalmann Frodason, Y. and Rønning, V. and Varley, J. B. and Vines, L.},

abstractNote = {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 ${\mathrm{Fe}}_{\text{GaI}}^{0/-}$ (E A = 0.66 eV), ${\mathrm{Fe}}_{\text{GaII}}^{0/-}$ (E A = 0.79 eV) and ${\mathrm{Ti}}_{\text{GaII}}^{+/\mathrm{0}}$ (E A = 1.03 eV) in the β-Ga2O3 samples studied here. Accumulatively-recorded SSPC spectra reveal several defect levels labeled ${T}_{\mathrm{1}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$–${T}_{\mathrm{6}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$ with onsets for optical absorption between 1.5 eV and 4.3 eV. The signature ${T}_{\mathrm{1}}^{\mathrm{E}\mathrm{F}\mathrm{G}}$ consists of several overlapping defect signatures, and is identified as being related to ${\mathrm{Fe}}_{\text{GaI}}^{0/-}$, ${\mathrm{Fe}}_{\text{GaII}}^{0/-}$ and ${\mathrm{Ti}}_{\text{GaII}}^{+/\mathrm{0}}$ by comparing measured and simulated accumulatively-recorded derivative SSPC spectra.},

doi = {10.1088/1367-2630/ab8e5b},

journal = {New Journal of Physics},

number = 6,

volume = 22,

place = {United Kingdom},

year = {2020},

month = {6}

}

DOI: 10.1088/1367-2630/ab8e5b

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