Synthesis of a-Si:H/μc-Si:H multilayer structures by hot wire chemical vapor deposition (HW-CVD) technique: Study of opto-electronic and photovoltaic properties

Abstract

Multilayer structures of the type a-Si:H/μc-Si:H were fabricated for the first time by hot wire chemical vapor deposition (HW-CVD) technique. These multilayers were studied for their opto-electronic and photovoltaic properties as a function of a-Si:H sublayer thickness. The microcrystalline phase of a-Si (μc-Si:H) of thickness 250 Å have been used to create drift field in these multilayer structures. The quantum size and photovoltaic effects are observed in these multilayer structures. The persistent photoconductivity measurements clearly indicate the existence of interface defects and spatial charge separation due to the formation of p-n junction field. The best photovoltaic performance was obtained with the fill factor 0.4062 and conversion efficiency ( η) 2.08% over an active area of 0.0132 cm 2. The advantage in these multilayer structures is that no hazardous gases are involved in the fabrication process because no intentional doping is performed and all depositions were carried out in a single deposition chamber.