Thermally stable visible-blind diamond photodiode using tungsten carbide Schottky contact

Abstract

We have developed a thermally stable, deep-ultraviolet (DUV) photodiode using tungsten carbide (WC) Schottky and Ti/WC ohmic contacts for a boron-doped homoepitaxial p-diamond epilayer. Effects of thermal annealing in an argon ambient on the electrical and photoresponse properties were investigated. Annealing at temperatures up to 550°C improves the rectifying current-voltage characteristics, resulting in a dramatic enhancement of DUV responsivity at 220nm by a factor of 4×103. A blind ratio as large as 105 between DUV and visible light has been achieved at a reverse bias as small as 1V. Development of the thermally stable WC-based Schottky and ohmic contacts provides a route for stable operation of a diamond photodetector at high temperatures.

Single‐Crystalline ZnS Nanobelts as Ultraviolet‐Light Sensors

“…[16][17][18] Being compared with all existing alternative materials, such as indirect band-gap diamond ($5.5 eV) and direct bandgap semiconductor ZnO ($3.4 eV), ZnS has a higher potential as a UV detector in this specific wavelength regime. [19,20] Despite the abundant research on the growth and optical properties of 1D ZnS nanostructures, [21][22][23] a study on nanostructure-based devices (in particular, UV sensors) has not yet been initiated, and presents a challenge. Very recently, we have developed a facile and effective thermalevaporation route for the synthesis of multiangular-branched ZnS nanostructures composed of needle-shaped tips with sharp UVlight band-gap emission and broad visible-light emission.…”

Large deep-ultraviolet photocurrent in metal-semiconductor-metal structures fabricated on as-grown boron-doped diamond

“…19 In summary, MSM structures with a very low dark current and a very high-UV photocurrent have been successfully achieved on as-grown boron-doped homoepitaxial diamond thin film. The spectral photoresponse shows six orders of magnitude discrimination between deep-UV and visible light for an applied voltage of 1 V. The degradation of the dark current after the high-temperature annealing was predictable and could be considerably reduced using a metalliccompound Schottky contact as a tungsten-carbide contact which was demonstrated thermally stable up to 550°C on diamond by Liao et al 27 High gain value was measured, which is contradicted the MSM Schottky device. A tentative plausible explanation refers to the reduction of the Schottky barrier height provoked by the illumination and the trapping states at the interface, which are a known fact in hydrogenated diamond surfaces.…”

Single Schottky-barrier photodiode with interdigitated-finger geometry: Application to diamond

“…We have developed diamond SPDs with semitransparent dotted Schottky contacts 6,7 and proposed that boron could induce an electron trap in the p-diamond epilayer. Therefore, it is available to develop the diamond SPD able to operate in both photoconductive and depletion modes.…”