Photoconductivity of InGaN/GaN multiple quantum well heterostructures

Photocurrent and photoconductivity of InGaN/GaN multiple quantum well heterostructures as a function of applied reverse bias is investigated. Optical excitation was carried out in blue and violet regions of the spectrum, and temperature was ranging from 10 to 300 K. We observed characteristic features related to consequently moving space charge boundary through the quantum wells. For each quantum well there is a range of reverse bias with negative differential conductivity when excited by blue light. Frequency and temperature measurements revealed the presence of at least two different mechanisms that determine the photoconductivity of the structures.