Deep-ultraviolet photodetectors from epitaxially grown NixMg1−xO

Abstract

Deep-ultraviolet (DUV) photodetectors were fabricated from high quality NixMg1−xO epitaxially grown by plasma-assisted molecular beam epitaxy on an approximately lattice matched MgO ⟨100⟩ substrate. A mid-range Ni composition (x=0.54) NixMg1−xO film was grown for DUV (λpeak<300 nm) photoresponse and the film was characterized by reflected high-energy electron diffraction, Rutherford backscattering spectroscopy, x-ray diffraction, and optical transmission measurements. Photoconductive detectors were then fabricated by deposition of symmetric interdigitated contacts (10 nm Pt/150 nm Au) with contact separations of 5, 10, and 15 μm. The detectors exhibited peak responsivities in the DUV (λpeak≈250 nm) as high as 12 mA/W, low dark currents (Idark<25 nA), and DUV:visible rejection ratio of approximately 800:1.