AlGaN based highly sensitive radio-frequency UV sensor

Abstract

The response of the AlGaN based radio-frequency (rf) sensor to deep ultraviolet (UV) illumination was investigated. Illumination by UV light emitting diodes with wavelengths from 280 to 375 nm significantly decreased rf oscillator frequency due to change in the impedance of AlGaN-based metal-semiconductor-metal structure. The UV-induced frequency shift attains 400 kHz from the oscillator dark frequency of 144.5 MHz with the highest sensitivity of 40 kHz/(μW/cm2) at 280 nm wavelength and UV power density less than 7.4 μW/cm2. The AlGaN-based rf oscillator allows for a wireless visible-blind and solar-blind UV sensing.

A Photoresponsive Red‐Hair‐Inspired Polydopamine‐Based Copolymer for Hybrid Photocapacitive Sensors

“…In all cases, either depletion or metal-oxide-semiconductor (MOS) capacitance is changed upon illumination. [4][5][6][7][8][9][10] Despite satisfactory performances, however, inorganic photocapacitive detectors, like those based on Si, suffer from drawbacks relating to high costs and high environmental impact. An attractive alternative would be offered by soft, friendly and more easily processable organic semiconductors.…”

“…Unfortunately, organic photocapacitive and photoresistive detectors generally show a low photo-effi ciency, due to the narrow spectral responsiveness, and have been little investigated, with phthalocyanine-based systems being the most signifi cant examples. [4][5][6][7][8][9][10] A possible convenient means of circumventing the intrinsic limitations of organic photocapacitors is to create a hybrid photosensitive device by coating a silicon substrate with a suitable organic fi lm (such as a conjugated polymer) serving as an 'enhancement layer' for broadband UV-visible detection. [ 11,12 ] To fulfi ll this scope, the organic layer should exhibit a broadband spectral response, absorbing light at high energies where the silicon photo-response is poor, and should emit at longer wavelengths.…”

Tunable and Wireless Photoimpedance Light Sensor

“…Such sensors can easily be integrated into wireless RF circuits. Conventional photocapacitive devices like Schottky diodes [1,2] work only on change in trap occupancy in the space charge region under illumination, which is usually small. Demonstrated MOS photocapacitors [3][4][5] use the modulation of inversion layer under illumination.…”

Spectroscopic Ellipsometry investigation on anisotropic optical properties of sputtered AlN films

“…Therefore, It is used in ultraviolet polarizer, optoelectronic displays, high temperature devices and short wavelength light source/detector applications [1,3,4]. AlN and Al-rich AlGaN alloy films find a crucial role in UV-LED (covering wavelengths from 210 to 375 nm), where the insulating properties can be used in the fabrication of GaN, GaAs and InP based electronic, radio-frequency UV sensor and optical devices [5,6]. Since they have high figure of merit for piezoelectric response, they are suitable for ultra-small mechanical pressures.…”