Nd3+ photoluminescence and its implication on the excitation mechanisms of Nd3+ in Nd doped hydrogenated amorphous silicon alloyed with carbon

Nd3+ photoluminescence from Nd doped, hydrogenated amorphous silicon alloyed with carbon (a-Si:H:C) is investigated. Nd-doped, a-Si:H:C films were deposited using electron cyclotron resonance plasma enhanced chemical vapor deposition of SiH4 and CH4 with concurrent sputtering of Nd. Clear Nd3+ luminescence peaks can be observed when excited with 488 nm light, indicating that Nd3+ ions in a-Si:H:C are excited via carriers generated in the a-Si:H:C. The energetics of Nd-doped a-Si:H:C rule out defect-related Auger excitation via mid-gap states. Based on the temperature and pump power dependence of Nd3+ and intrinsic a-Si:H:C photoluminescence intensities, we identify excitation via Nd-related defects with a strong coupling to Nd3+ as a possible excitation mechanism for Nd in a-Si:H:C.