Inline RF sputtered TAZO films for applications in hydrogenated amorphous silicon thin film solar cells

摘要

In this paper, we aim to evaluate feasibility of replacing tin oxide (SnO_2) films by in-line sputtered (titanium, aluminum)-doped zinc oxide (TAZO) as a front electrode of hydrogenated amorphous silicon (a-Si:H) thin film solar cells. The HC1 wet-etching process and the device performances are investigated and optimized. The results show that the textured TAZO can have a lower sheet resistance of 7 Ω/square and a higher haze of 22% compared to commercial Asahi-U SnO_2 films. The a-Si:H solar cells with a TAZO front contact is found to have a low fill factor due to a poor TAZO/p-a-Si:H interface. However, the interface problem can be significantly improved by inserting a microcrystalline p-layer silicon thin-film. In addition, the reproducibility of the wet-etching process is investigated. The fluctuation in the haze of the etched TAZO films can be obviously reduced when a multi-step wet-etching process is used. Moreover, the light soaking test is performed on the TAZO films. Only slight degradation in film properties indicates high stability with respect to time. These results encourage potential adoption of cost-effective in-line sputtered TAZO films as an alternative for the front contact of a-Si:H thin film solar cells.