Properties of hydrogenated amorphous silicon prepared by alternatively repeating chemical-vapor deposition from disilane and hydrogen plasma treatment

Experimental studies have been carried out to characterize hydrogenated amorphous silicon prepared by alternatively repeating chemical-vapor deposition (CVD) from disilane and hydrogen plasma (HP) treatment (referred to as HP treated CVD a-Si:H). It has been found that hydrogen plasma treatment induces structural relaxation of Si network in addition to the passivation of Si dangling bonds. Two types of defect states with different Gaussian energy distribution exist in this material, and this type of distribution has been found to be common in undoped a-Si:H prepared by a variety of methods. High film quality, i.e., a low defect density (<1016 cm−3) and a fairly long ambipolar diffusion length (0.12 μm), and significant reduction of light-induced changes have been simultaneously achieved in HP treated CVD a-Si:H. Steady state transport of electrons and holes under illumination are controlled by the states other than neutral Si dangling bond state (D0). The behavior of these states with long exposure to light is different from that of D0.