Study on the deposition of amorphous silicon and ito thin films for heterojunction solar cell application

Abstract

In the heterojunction with intrinsic thin-layer (HIT) solar cell structure studied in this work, an intrinsic amorphous silicon (a-Si) layer followed by a n-type amorphous silicon was deposited on a p-type Czochralski (CZ) monocrystalline silicon (c-Si) wafer by plasma enhanced chemical vapor deposition (PECVD) method to form an heterojunction device. Then, indium tin oxide (ITO) layer was formed by DC magnetron sputtering as the top electrode and the anti-reflection coating layer. In order to obtain the high efficiency heterojunction structure, two important aspects were focused: improving the passivation properties of a-Si/c-Si heterojunction and reducing the light absorption and the sheet resistance of ITO layers. It was found that hydrogenated amorphous silicon (a-Si:H) layers can be grown at low substrate temperature, about 200°C. High-quality ITO layers with the sheet resistance less than 15 ohm/sq and the transmittance of about 70%, can be deposited at relatively low DC power (50W).