We report on a new approach to quickly synthesize high-quality single crystalline wide band gap silicon carbide (SiC) films for development of high-performance deep ultraviolet (UV) photodetectors. The fabricated SiC based UV photodetectors exhibited high response while maintaining cost-effectiveness and size miniaturization. Focus of the experiments was on studies of electrical and electronic properties, as well as responsivity, response and recovery times, and repeatability of the deep UV photodetectors. Raman scattering spectroscopy and scanning electron microscope (SEM) were used to characterize the SiC materials. Analyses of the SEM data indicated that highly flat SiC thin films have been obtained. Based on the synthesized SiC, deep UV detectors are designed, fabricated, and tested with various UV wavelength lights at different radiation intensities. Temperature effect and bias effect on the photocurrent strength and signal-to-noise ratio, humidity effect on the response time and recovery time of the fabricated detectors have been carefully characterized and discussed. The detectors appear to have a very stable baseline and repeatability. The obtained responsivity is more than 40% higher compared to commercial detectors. The good performance of the photodetectors at operating temperature up to 300 °C remains nearly unchanged.

We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity. Deep UV detectors based on the obtained BNNSs were designed, fabricated, and tested. The bias and temperature effects on the photocurrent strength and the signal-to-noise ratio have been carefully characterized and discussed. A significant shift in the cut off wavelength of the BNNSs based photodetectors was observed suggesting a band gap reduction as a result of the BNNSs’ collective structure. The newly designed photodetector presented exceptional properties: a high sensitivity to weak intensities of radiation in both UVC and UVB range while remaining visible-blind, and a high signal-to-noise ratio operation even at temperatures as high as 400 °C. In addition, the BNNSs based photodetector exhibited potential for self-powered operation.

Diamond nanowires have recently drawn substantial attention because of their unique physical and chemical properties for electrochemical sensors, optoelectronics, and nanophotonics applications. However, diamond nanowire-based ultraviolet photodetectors have not been reported because of the challenges involved in synthesizing crystalline diamond nanowires with controllable morphologies and, more fundamentally, the material's high carrier concentration with low mobilities that limits the obtainable photoresponsivity. The synergetic integration of ultrananocrystalline diamond (UNCD) nanowires with nanoplasmonic enhancement by noble metal nanoparticles is a very promising approach to overcome these shortcomings. Here we report the fabrication of boron-doped ultrananocrystalline diamond nanowires functionalized with the platinum nanoparticles to form self-powered ultraviolet photodetectors that exhibit an ultrahigh photoresponsivity of 388 Amp/Watt at 300 nm wavelength, a fast response time around 20 ms, and a good UV/visible rejection ratio of about 5 orders of magnitude under zero-bias condition.

High-quality single crystalline Gallium Nitride (GaN) semiconductor has been synthesized using molecule beam epitaxy (MBE) technique for development of high-performance deep ultraviolet (UV) photodetectors. Thickness of the films was estimated by using surface profile meter and scanning electron microscope. Electronic states and elemental composition of the films were obtained using Raman scattering spectroscopy. The orientation, crystal structure and phase purity of the films were examined using a Siemens x-ray diffractometer radiation. The surface microstructure was studied using high resolution scanning electron microscopy (SEM). Two types of metal pairs: Al-Al, Al-Cu or Cu-Cu were used for interdigital electrodes on GaN film in order to examine the Schottky properties of the GaN based photodetector. The characterizations of the fabricated prototype include the stability, responsivity, response and recovery times. Typical time dependent photoresponsivity by switching different UV light source on and off five times for each 240 seconds at a bias of 2V, respectively, have been obtained. The detector appears to be highly sensitive to various UV wavelengths of light with very stable baseline and repeatability. The obtained photoresponsivity was up to 354 mA/W at the bias 2V. Higher photoresponsivity could be obtained if higher bias was applied but it would unavoidably result in a higher dark current. Thermal effect on the fabricated GaN based prototype was discussed.