Field Effect Controlled Photoresistors Based on Chemically Deposited PbS Films

Abstract

MOS-like structures were obtained by chemical deposition of a polycrystalline PbS thin film on top of a silicon dioxide/Si substrate. Gold ohmic electrodes in coplanar configuration were subsequently deposited by vacuum evaporation on PbS surface (drain and source electrodes). The gate aluminum electrode was deposited on the back of the Si substrate. The dependence of the photoconductive signal, generated in the PbS film, on the gate voltage was studied for wavelengths ranging between 800 nm and 3000 nm at room temperature as well as at low temperatures. It was found that the relative variation of the signal could be as high as 50 % for gate voltages ranging between -30 V and +30 V. Two possible mechanisms are proposed to explain the signal variation with the gate voltage: 1) Variation of the depleted region's thickness in the PbS film, that leads to a variation of the conduction channel's resistance (the reference resistance called, also, the dark resistance), 2) The possible variation of the majority carriers (holes) life-time due to the electron blocking at the PbS/oxide interface when positive gate voltages are applied on the back electrode. Integrated IR detectors with controlled sensitivity in the 800-3000 nm range can be manufactured at a relatively low cost using the PbS/oxide/Si MOS-like structure.

Synthesis of single-crystal PbS nanorods via a simple hydrothermal process using PEO–PPO–PEO triblock copolymer as a structure-directing agent

“…Among these materials, PbS, as an important IV-VI semiconductor, is an attractive sulfide semiconductor with a special narrow direct band gap of 0.41 eV and a large excitation Bohr radius of 18 nm, which permits sizequantum confinement effects to be clearly visible even for the large particles [10]. With novel and excellent optical and electronic properties, nanoscaled PbS has been widely used for IR detectors [11], solar cells [12] and electroluminescent devices [13].…”

Simple and Productive Method to Develop Highly Sensitive and Fast Infrared Photodetector Using Spray Deposited Nanocrystalline PbS Thin Film

“…Lead sulfide (PbS) with a cubic structure and a small bandgap (0.4 eV) has reported high photosensitivity in the infrared (IR) range [1][2][3][4]. Along with this PbS nanostructures are also used as temperature sensors, solar cells, photomultipliers, photoresistors, and selective sensors based on lead ions [5][6][7]. One of the most intriguing properties of PbS and other lead chalcogenides is the significant increase in band gap energy with increasing temperature, which is the polar opposite of all other semiconductors [8].…”