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Optical Properties of Mist CVD Grown α-Ga2O3

Muazzam, UU and Chavan, P and Raghavan, S and Muralidharan, R and Nath, DN (2020) Optical Properties of Mist CVD Grown α-Ga2O3. In: IEEE Photonics Technology Letters, 32 (7). pp. 422-425.

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Official URL: https://doi.org/10.1109/LPT.2020.2976450


We report on the study of optical properties of mist CVD grown α-Ga2O3 with the observation of excitonic absorption in spectral responsivity measurements. 163 nm of Ga2O3 was grown on sapphire using Ga-(acac)3 as the starting solution at a substrate temperature of 450°C. The film was found to be crystalline and of α-phase with an on-axis full width at half maximum (FWHM) of 92 arcsec as confirmed from X-ray diffraction scans. The Eliott-Toyozawa model was used to deduce band gap and excitonic binding energy from the absorption spectrum. The exciton binding energy was extracted to be 90 meV with large Gaussian spread of 0.195 eV. From spectral responsivity (S.R) measurements, a similar value of excitonic binding energy was found. This unusually huge binding energy is attributed to strong interaction between longitudinal optical (LO) phonons and excitons. Further, metal-semiconductor-metal (MSM) photodetectors (PD) with lateral inter-digitated geometry were fabricated on the film. A sharp band edge was observed at 229 nm ( 5.42 eV) in the spectral response with peak responsivity of 1 A/W at a bias of 20 V. The UV to visible rejection ratio was found to be 100 while the dark current was measured to be 0.1 nA at a bias voltage of 20 V. © 1989-2012 IEEE.

Item Type: Journal Article
Publication: IEEE Photonics Technology Letters
Publisher: Institute of Electrical and Electronics Engineers Inc.
Additional Information: Copyright of this article belongs to the Institute of Electrical and Electronics Engineers Inc.
Keywords: Absorption spectroscopy; Energy gap; Excitons; Gallium compounds; Optical properties; Photodetectors; Photons; Sapphire; Semiconductor quantum wells, Exciton-binding energy; Excitonic absorption; Longitudinal optical phonons; Metal semiconductor metal photodetector; Mist CVD; Spectral responsivity; Substrate temperature; UV photodetectors, Binding energy
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 22 Apr 2021 08:59
Last Modified: 10 Sep 2022 07:22
URI: https://eprints.iisc.ac.in/id/eprint/65054

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