INFLUENCE OF GROWTH TEMPERATURES ON THE PHOTORESPONSE OF LOW-TEMPERATURE-GROWN GAAS-AS P-I-N-DIODES

We report a study of the sub-bandgap photoresponse of p-i-n photodetec tors with 1 mu m low-temperature intrinsic layers, and its dependence on the growth temperature of the intrinsic layer. Diodes with intrinsi c layers grown near 250 degrees C exhibit the highest photoresponse. T he photoresponse decreases gradually as the growth temperature is rais ed above 250 degrees C. For growth temperatures at or below 200 degree s C, a drastic drop in the photoresponse is observed, along with degra dation of crystal quality in the material. The extracted internal Scho ttky barrier heights are found to be within the range 0.7-0.8 eV.