The effect of strain in InP/InGaAs quantum-well infrared photodetectors onthe operating wavelength

We report on InP/InGaAs quantum-well infrared photodetectors (QWIPs) that c over the spectral range from 8 to 11 mum. The only previously reported oper ating wavelength for QWIPs of the same material system was around 8 mum. Th e higher operating wavelengths were achieved by including the strain as an additional band gap engineering parameter. According to our calculations, t he InP/InGaAs lattice-mismatched multiple quantum well structures are suita ble for design QWIPs covering the 5.5-11 mum range. We demonstrate five dif ferent QWIP structures with bound-to-bound and bound-to-continuum transitio ns for photodetection in the 8-12 mum atmospheric window. The calculations are in very good agreement with the experimental data. We found that the In P/InGaAs material system is more flexible than GaAs/AlGaAs because it has a n additional degree of freedom-the strain for band gap engineering design. (C) 2001 American Institute of Physics.