Unusual conduction mechanism of n-type β-Ga2O3: A shallow donor electron paramagnetic resonance analysis

• Published in: Journal of applied physics 2020-09, Vol.128 (12)
• Main Authors: von Bardeleben, H. J., Cantin, J. L.
• Format: Article
• Language: English
• Subjects: Applied physics; Clustering; Conduction bands; Conduction electrons; Electron paramagnetic resonance; Electron spin; Electrons; Frequency ranges; Gallium oxides; Hopping conduction; Ionization; Line broadening; Line shape; Room temperature; Signal processing; Spectrum analysis; Spin resonance; Temperature; Temperature dependence; Zinc oxide
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0023546

We have investigated the conduction mechanism in n-type, Si doped β-Ga2O3 bulk samples and evidenced carrier dynamics in the GHz frequency range at room temperature by electron paramagnetic resonance (EPR) spectroscopy. The Si shallow donor EPR and conduction electron spin resonance (CESR) spectra show an unusual temperature dependence of the linewidth and line shape, which reveals a variable range hopping conduction and donor clustering. The temperature dependence of the EPR signal intensity can be fitted with two thermally activated processes with energies of 4 meV and 40 meV in the below and above 40 K temperature range. The value of 40 meV is attributed to the ionization energy of the Si shallow donor, indicating that hopping proceeds via the conduction band. Above T = 130 K and up to room temperature, the conduction electron spin resonance (CESR) can be observed with a decreasing linewidth of ΔB