The deep level properties of S-, Se-, and Te-doped layers of In0.49Ga0.51P and In0.32Ga0.68P that had been grown by means of liquid phase epitaxy were studied by using deep level transient spectroscopic and capacitance-temperature measurements. It was found that all of the impurities formed deep donor states in In0.32Ga0.68, but only S did so in In0.49Ga0.51P. On the basis of the observed dependence of the deep level properties upon the impurity species, and of the existence of persistent photoconductivity, these impurity-related deep levels were attributed to DX centers. The activation energies of group-VI DX centers decreased as the mass number of the impurity atom increased. It was observed that the binding energies of S-related DX centers were larger than those of Se- and Te-related centers.

S.D.Kwon, H.K.Kwon, B.D.Choe, H.Lim: Applied Physics Letters, 1995, 67[17], 2533-5