High-Gain Zn1-XMgX O-Based Ultraviolet Photodetectors On Al2O3 And Ligao2Substrates

Keywords

Lithium gallates; Molecular beam epitaxy; Ultraviolet photodetectors; Zinc oxide films

Abstract

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 ~ 0.44) thin-film heterostructures grown on sapphire (α-Al2O3) substrates and w-Zn1-xMgx O (x ~ 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, α-Al2O3 grown devices exhibit peak responsivity of ~7.6 A/W at 280 nm while LiGaO2 grown samples demonstrate peak performance of ~119.3 A/W, albeit in the UV-A regime (~324 nm). High photoconductive gains (76, 525) and spectral rejection ratios (~103, ~104) were obtained for devices grown on α-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.

Publication Date

1-1-2015

Publication Title

Physica Status Solidi - Rapid Research Letters

Volume

9

Issue

1

Number of Pages

82-86

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/pssr.201409311

Socpus ID

84921433437 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84921433437

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