Nanoscale Si/SiGe based quantum well infrared photodetectors

Abstract

In this study, the photoresponse of Si/ SiGe based quantum well infrared photodetector structures was investigated. Two samples of SiGe and other SiGeC quantum well heterostructures were grown. Carbon was incorporated to reduce the strain and to increase the film stability and the bandgap. After processing the responsitivity of the detector was measured as a function of wavelength using the UV- visible spectrophotometer. Highest responsitivity of 1151.55mA/W has been shown, which very well lies in the infrared region. We also tried to detect any intersubband transitions. However, they were not observed in the samples due to a number of reasons. To obtain further insights in the structural quality of sample photoluminescence spectroscopy detecting the interband electron-hole pair recombination was performed. With the rise in the temperature from 5K to 70K the PL peak shifted form about 1.13E to about 1.25E for Sio.75Geo.25 material. The X-ray diffraction measurements were also carried out. The diffraction pattern of the SiGeC sample looks similar to SiGe at the first glance. But on close analysis and comparison of the diffraction patterns, the reduction of strain is evident for the former case.