Wavelength extended InGaAs/InAlAs/InP photodetectors using n-on-p configuration optimized for back illumination

Using n-on-p InGaAs/InAlAs/InP heterojunction structure with relative thin Be doped linearly graded InxAl1-xAs as buffer layer, wavelength extended InGaAs photodiodes with 50% cutoff wavelength of 2.0 mu m and 2.4 mu m at room temperature have been grown by using gas source MBE with a convenient but reliable correlative ramping procedure, and their dark current performance in a wide temperature range have been investigated. For 300 pm diameter detectors at 290 K, typical R(0)A and dark current at 10 mV reverse bias are 760 Omega cm(2)/11.3 nA for cutoff wavelength of 2.0 mu m, and 104 Omega cm(2)/75.1 nA for cutoff wavelength of 2.4 mu m. Room temperature peak cletectivity D lambda P center dot reaches 13E11 cm Hz(1/2)/W and 6.5E10 cm Hz(1/2)/W, respectively measured using 900 K black body source. For back illumination the parameter optimization of n-on-p configuration is much easier than those of p-on-n, also the structure quality of the n-on-p is better than those of p-on-n because of the high Be doping in the linear graded buffer layer instead of Si. (C) 2008 Elsevier B.V. All rights reserved.