The new oxide paradigm for solid state ultraviolet photodetectors
| Autor: | Ryan McClintock, Xavier Arrateig, Manijeh Razeghi, S. Harel, Ferechteh H. Teherani, D. J. Rogers, Philippe Bove, E. Frisch, V. E. Sandana |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
business.industry Band gap Photodetector 02 engineering and technology Orders of magnitude (numbers) 021001 nanoscience & nanotechnology medicine.disease_cause 01 natural sciences Spectral line Pulsed laser deposition 010309 optics Responsivity chemistry.chemical_compound chemistry 0103 physical sciences Silicon carbide medicine Optoelectronics 0210 nano-technology business Ultraviolet |
| Zdroj: | Oxide-based Materials and Devices IX. |
| DOI: | 10.1117/12.2319505 |
| Popis: | The bandgap of wurzite ZnO layers grown on 2 inch diameter c-Al2O3 substrates by pulsed laser deposition was engineered from 3.7 to 4.8 eV by alloying with Mg. Above this Mg content the layers transformed from single phase hcp to mixed hcp/fcc phase before becoming single phase fcc above a bandgap of about 5.5 eV. Metal-Semiconductor-Metal (MSM) photodetectors based on gold Inter-Digitated-Transducer structures were fabricated from the single phase hcp layers by single step negative photolithography and then packaged in TO5 cans. The devices gave over 6 orders of magnitude of separation between dark and light signal with solar rejection ratios (I270 : I350) of over 3 × 105 and dark signals of 300 pA (at a bias of -5V). Spectral responsivities were engineered to fit the “Deutscher Verein des Gas- und Wasserfaches” industry standard form and gave over two decade higher responsivities (14 A/W, peaked at 270 nm) than commercial SiC based devices. Homogeneous Ga2O3 layers were also grown on 2 inch diameter c-Al2O3 substrates by PLD. Optical transmission spectra were coherent with a bandgap that increased from 4.9 to 5.4 eV when film thickness was decreased from 825 to 145 nm. X-ray diffraction revealed that the films were of the β-Ga2O3 (monoclinic) polytype with strong (-201) orientation. β-Ga2O3 MSM photodetectors gave over 4 orders of magnitude of separation between dark and light signal (at -5V bias) with dark currents of 250 pA and spectral responsivities of up to 40 A/W (at -0.75V bias). It was found that the spectral responsivity peak position could be decreased from 250 to 230 nm by reducing film thickness from 825 to 145 nm. This shift in peak responsivity wavelength with film thickness (a) was coherent with the apparent bandgap shift that was observed in transmission spectroscopy for the same layers and (b) conveniently provides a coverage of the spectral region in which MgZnO layers show fcc/hcp phase mixing. |
| Databáze: | OpenAIRE |
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