High-gain Zn1-xMgxO-based ultraviolet photodetectors on Al2O3 and LiGaO2 substrates
Abbreviated Journal Title
Phys. Status Solidi-Rapid Res. Lett.
lithium gallates; molecular beam epitaxy; zinc oxide films; ultraviolet; photodetectors; EPITAXIAL-GROWTH; MGXZN1-XO ALLOY; THIN-FILMS; ALGAN; ZNO; Materials Science, Multidisciplinary; Physics, Applied; Physics, ; Condensed Matter
We report the fabrication and characterization of highly responsive ZnMgO-based ultraviolet (UV) photodetectors in the metal-semiconductor-metal (MSM) configuration for solar-blind/visible-blind optoelectronic application. MSM devices were fabricated from wurtzite Zn1-xMgx O/ZnO (x approximate to 0.44) thin-film heterostructures grown on sapphire (-Al2O3) substrates and w-Zn1-xMgx O (x approximate to 0.08), grown on nearly lattice-matched lithium gallate (LiGaO2) substrates, both by radio-frequency plasma-assisted molecular beam epitaxy (PAMBE). Thin film properties were studied by AFM, XRD, and optical transmission spectra, while MSM device performance was analyzed by spectral photoresponse and current-voltage techniques. Under biased conditions, -Al2O3 grown devices exhibit peak responsivity of approximate to 7.6 A/W at 280 nm while LiGaO2 grown samples demonstrate peak performance of approximate to 119.3 A/W, albeit in the UV-A regime (approximate to 324 nm). High photoconductive gains (76, 525) and spectral rejection ratios (approximate to 10(3), approximate to 10(4)) were obtained for devices grown on -Al2O3 and LiGaO2, respectively. Exemplary device performance was ascribed to high material quality and in the case of lattice-matched LiGaO2 films, decreased photocarrier trapping probability, presumably due to low-density of dislocation defects. To the best of our knowledge, these results represent the highest performing ZnO-based photodetectors on LiGaO2 yet fabricated, and demonstrate both the feasibility and substantial enhancement of photodetector device performance via growth on lattice-matched substrates. ((c) 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
Physica Status Solidi-Rapid Research Letters
"High-gain Zn1-xMgxO-based ultraviolet photodetectors on Al2O3 and LiGaO2 substrates" (2015). Faculty Bibliography 2010s. 6729.