Highly Sensitive Hydrogen Sulfide Sensor Based on GaN/GaInN Heterostructure

Abstract

Accurate detection of gases such as hydrogen sulfide in the exhaled human breath is of great interest for medical professionals as it can possibly help in the early detection of organ malfunction and other diseases. GaInN heterostructure sensors are sensitive to the changes in the surface potential caused by the adsorption of gas molecules. A quantum well (QW) placed close to the surface experiences a change in the quantum‐confined Stark effect and as a result shifts its photoluminescence signal. Several parameters of the GaInN sensors grown by metal organic vapor phase epitaxy are optimized such as the GaN cap layer, QW thickness, and doping concentration. Moreover, how various metal functionalization layers can improve its sensitivity and selectivity is investigated. Gold (Au) and Silver (Ag) shows sensitivity to hydrogen sulfide in the 10–100 parts per billion (ppb) range. Ammonia gas is also detected in the 5–10 range (ppm) with a sensor structure covered with a thin gold layer.