Complexes of vacancy at indium site with one to four hydrogen atoms and isolated hydrogen or hydrogen dimer and other infrared absorption lines, tentatively be assigned to hydrogen related defects were investigated by FTIR. Hydrogen can passivate imperfections, thereby eliminating detrimental electronic states from the energy bandgap.Incorporated hydrogen can introduce extended defects and generate electrically-active defects. Hydrogen also can acts as an actuator for creating of antistructure defects. Isolated hydrogen related defects(e.g. H12
+) may play an important role in the conversion of the annealed wafers from semiconducting to the semi-insulating behavior. H2
+ may be a deep donor, whose energy level is very near the iron deep acceptor level in the energy gap.