Defect Formation During Deposition of Undoped a-Si:H BY PE-CVD

<jats:title>Abstract</jats:title><jats:p>Dependence of the as-grown defect concentration in PECVD undoped a-Si:H on the deposition parameters, i.e., substrate temperature and precursor density in the plasma produced by H<jats:sub>2</jats:sub> dilution of SiH<jats:sub>4</jats:sub> gas, is investigated. It is found that the defect density behaves similarly to the concentration of SiH<jats:sub>2</jats:sub> configuration in the films deposited at substrate temperatures below 300 °C. The defect concentration, however, varies proportionally to about the 3rd to 4th power of the SiH<jats:sub>2</jats:sub> concentration depending on the deposition condition. Based on the surface reaction mechanism proposed in our previous paper, a large enthalpy change is expected to accompany the bimolecular reaction of the adsorbed SiH<jats:sub>3</jats:sub> radicals, which incorporates the SiH<jats:sub>2</jats:sub> configuration into the network. Characteristics of the defect formation caused by tile breaking Si-Si bond near the growing surface owing to this energy is compared with those of the Staebler-Wronski effect. Both similarity in dependence on II atom concentration and difference in annealing temperature are discussed. It is concluded that the as-grown defects are most likely formed during deposition owing to the large enthalpy change accompanying the bimolecular surface reaction.</jats:p>