“…Many efforts have been made to extend the cutoff wavelength of the In x Ga 1-x As photodetectors from about 1.7 lm (x = 0.53, lattice matched to InP substrate) to the longer wavelength side for the importance of the short wave infrared (SWIR) band of 1-3 lm [1][2][3][4][5][6][7][8][9][10][11], which exhibiting particular spectroscopic features including strong water absorption band around 1.4, 1.9 and 2.7 lm, as well as the high contrast for earth observation from the satellite [12]. However, to our knowledge the longest cutoff wavelength of the detectors at room temperature is still around 2.6-2.7 lm [2,11], which corresponding to a lattice mismatch of about 2.2% for x $ 0.85.…”