| AVS 58th Annual International Symposium and Exhibition | |
| Energy Frontiers Focus Topic | Monday Sessions |
| Session EN+PS-MoM |
| Session: | Plasmas for Photovoltaics & Energy Applications |
| Presenter: | Erwin Kessels, Eindhoven University of Technology, the Netherlands |
| Correspondent: | Click to Email |
Photovoltaics has become a very innovative field of research and manufacturing due to the continuous improvement in the solar cell cost/performance ratio and its tremendous growth opportunities (past average annual growth rate of 40%). Several innovations with respect to the improvement of the cell efficiency lie in the field of thin film technology, not only for thin-film solar cells but also for crystalline silicon solar cells which are currently still dominating the market (87% market share in 2010). One particular trend is the application of ultrathin films or “functional nanolayers” for solar cell interface engineering. In crystalline silicon technology these nanolayers have as a main application the reduction of charge carrier recombination at interfaces through “surface passivation”. Plasma-based deposition processes such as plasma-enhanced chemical vapor deposition (CVD) are key for the preparation of such films and recently the interest also shifted to (plasma-enhanced) atomic layer deposition (ALD) processes due to their precise growth control and their excellent uniformity and conformality [1]. Moreover, ultrathin films of < 10 nm have been found feasible in terms of reaching very-well passivated surfaces. In this contribution, the application of ultrathin films of various materials such as a-Si:H, a-SiNx:H, SiO2, and in particular Al2O3 will be addressed. The preparation methods will be described as well as the relevant surface reaction mechanisms during the film synthesis. Passivation and solar cell results will be presented with a main emphasis on the key mechanisms underlying the good passivation performance of the ultrathin films. Also the market feasibility of new ALD technologies, e.g., in terms of high throughput processing, will be addressed.
[1] Atomic layer deposition: prospects for solar cell manufacturing, W.M.M. Kessels, et al., Proc. 33rd IEEE Photovoltaic Specialist Conference, San Diego, U.S.A. (2008).