Light‐induced defects in hydrogenated amorphous silicon observed by picosecond photoinduced absorption

Phosphorus‐doped and boron‐doped hydrogenated amorphous silicon were studied by photoinduced absorption (PA) in the time range from 2 to 1800 ps. Prolonged light exposure (ℏω=2.0 eV) causes PA to decay more rapidly. The data are fit to a multiple trapping model. Minority carriers get trapped at deep defect states whose density increases with light exposure. These results are consistent with the interpretation that the light‐induced defects in amorphous silicon are dangling bonds.