Evaluation of oxygen precipitation behavior in n-type Czochralski-Si for photovoltaic by infrared tomography: Effects of carbon concentration and annealing process conditions

摘要

In this study, we evaluated the effects of carbon and annealing process conditions on the oxygen precipitation in an n-type Czochralski (Cz) wafer for solar cells by infrared light scattering tomography (IR-LST). It was confirmed that precipitates grow larger and denser as carbon concentration increase. Thus, carbon promotes oxygen precipitation. We also evaluated the effect of oxygen precipitation on the minority carrier lifetime by photoluminescence (PL) imaging. It was confirmed that the interface between the precipitate and the Si matrix is a dominant recombination center since the surface area of the precipitate obtained by IR-LST measurement and the PL intensity show good correlation. In addition, it was also confirmed that carbon is involved in the supply of interstitial oxygen to precipitates through the formation and extinction of the thermal donor. We believe that it is important to understand and control the effect of carbon of controlling the oxygen precipitation behavior. (C) 2018 The Japan Society of Applied Physics