Temperature Dependence of Dark Current in Quantum Well Infrared Detectors

The I-V characteristics of a bound-to-continuum QWIP device with Al(0.37)Ga(0.63)As barriers of 23 nm, In(0.1)Ga(0.9)As wells of 3.6 nm, and a doping three-dimensional density of carriers in the well of 10(exp 18) /cu cm were gathered and analyzed for various temperatures. The device was cooled with a closed cycle refrigerator, and the data were acquired using the Agilent 4155B Semiconductor Parameter Analyzer. Dark current in the device was qualitatively explained, then further examined with a thermionic emission model. Using this model and an iterative Matlab program we were able to establish the energy levels within the well. In addition, the dark current limited detectivity (D*) of the device was determined as a function of the temperature in the 10 - 170 K range. It was found that the D* degrades at temperatures above 80 K due to excess thermionic emission from the quantum well. The details of the laboratory setup and test system and process are included with the intent to provide future students with simple and comprehensive procedural insight. The original document contains color images.