Avalanche Photodetector Based on InAs/InSb Superlattice

This work demonstrates a mid-wavelength infrared InAs/InSb superlattice avalanche photodiode (APD). The superlattice APD structure was grown by molecular beam epitaxy on GaSb substrate. The device exhibits a 100 % cut-off wavelength of 4.6 µm at 150 K and 4.30 µm at 77 K. At 150 and 77 K, the device responsivity reaches peak values of 2.49 and 2.32 A/W at 3.75 µm under −1.0 V applied bias, respectively. The device reveals an electron dominated avalanching mechanism with a gain value of 6 at 150 K and 7.4 at 77 K which was observed under −6.5 V bias voltage. The gain value was measured at different temperatures and different diode sizes. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device.

Polymeric Transducers: An Inkjet Printed B-Field Sensor with Resistive Readout Strategy

Magnetic field sensors are successfully used in numerous application contexts such as position sensing, speed detection, current detection, contactless switches, vehicle detection, and electronic compasses. In this paper, an inkjet printed magnetic sensor, based on the magneto-mechanical sensing principle, is presented together with a physical model describing its physical behavior and experimental results. The main novelties of the proposed solution consist of its low cost, rapid prototyping (printing and drying time), disposability, and in the use of a commercial low-cost printer. A measurement survey has been carried out by investigating magnetic fields belonging to the range 0–27 mT and for different values of the excitation current forced in the actuation coil. Experimental results demonstrate the suitability of both the proposed sensing strategy and model developed. In particular, in the case of an excitation current of 100 mA, the device responsivity and resolution are 3700 µε/T and 0.458 mT, respectively.

Optical and Electrical Character of SICGe/SIC Heterojunction Phototransistor with Charge Compensation Layer

The optical properties of SiCGe epitaxial on 6H-SiC substrate by LPCVD were investigated by transmittance measurements. Swanepoel methods were used in order to calculate the optical properties of the sample. The result was use to simulation the performance of n-SiC/p-SiCGe/n-SiCGe heterojunction phototransistor with charge compensation layer. Simulation results show that with wide bandgap SiC emitter and p-type SiCGe charge-compensation layer, device responsivity doubled and breakdown voltage increased from 440V to 580V for the given structure

Evidence of Responsivity and Breakdown Voltage Improvement in SiCGe/SiC Phototransistor with Charge Compensation Layer

An n-SiC/p-SiCGe/n-SiCGe heterojunction phototransistor with charge compensation layer has been simulated with commercial simulator MEDICI. With wide bandgap SiC emitter and p-type SiCGe charge-compensation layer, device responsivity and breakdown voltage has been improved. It is found that with p-type SiCGe layer, the responsivity is nearly two times of without one. Furthermore, flat electrical field distribution during off-state enable it supports higher reverse bias, thus breakdown voltage increased from 450V to 580V for the given structure, and both breakdown voltage and responsivity increase with light absorption region length.

High-Performance Solar-Blind AlGaN Schottky Photodiodes

High-performance solar-blind AlGaN-based Schottky photodiodes have been demonstrated. The detectors were fabricated on MOCVD-grown AlGaN/GaN hetero-structures using a microwave-compatible fabrication process. Current-voltage, spectral responsivity, noise, and high-speed characteristics of the detectors were measured and analyzed. Dark currents lower than 1 pA at bias voltages as high as 30 V were obtained. True solar-blind detection was achieved with a cut-off wavelength lower than 266 nm. A peak device responsivity of 78 mA/W at 250 nm was measured under 15 V reverse bias. A visible rejection of more than 4 orders of magnitude was observed. The solar-blind photodiodes exhibited noise densities below the measurement setup noise floor of 3×10−29 A2/Hz around 10 KHz. High-speed measurements at the solar-blind wavelength of 267 nm resulted in 3-dB bandwidths as high as 870 MHz.