Self-aligned selective emitter plasma-etchback and passivation process for screen-printed silicon solar cells
- Sandia National Labs., Albuquerque, NM (United States)
- New Mexico Univ., Albuquerque, NM (United States)
- Solarex Corp., Frederick, MD (United States)
Plasma-enhanced chemical vapor deposition (PECVD) is a cost-effective, performance-enhancing technique that can provide surface passivation and produce an effective antireflection coating layer at the same time. To gain the full benefit from improved emitter surface passivation on cell performance, it is necessary to tailor the emitter doping profile so that the emitter is lightly doped between the gridlines, but heavily doped under them. This selectively patterned emitter doping profile has historically been obtained by using expensive photolithographic or screen-printed alignment techniques and multiple high-temperature diffusion steps. We built on a self-aligned emitter etchback technique first described by Spectrolab. We included PECVD-nitride deposition because the low- recombination emitter produced by the etchback requires good surface passivation for improved cell performance. The nitride also provides a good antireflection coating. We studied whether plasma-etching techniques can use standard screen-printed gridlines at etch masks to form self-aligned, patterned-emitter profiles on multicrystalline (MC-Si) cells from Solarex Corp. This investigation determined that reactive ion etching (RIE) is compatible with using standard, commercial, screen printed gridlines as etch masks to form self- aligned, selectively-doped emitter profiles. This process results in reduced gridline contact resistance when followed by PECVD treatments, an undamaged emitter surface easily passivated by plasma-nitride, and a less heavily doped emitter between gridlines for reduced emitter recombination. This allows for heavier doping beneath the gridlines for even lower contact resistance, reduced contact recombination, and better bulk defect gettering. Our results found improvement of half a percentage point in cell efficiency when the self-aligned emitter etchback was combined with the PECVD-nitride surface passivation treatment.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 368373
- Report Number(s):
- SAND-96-1920C; CONF-9608116-2; ON: DE96013900
- Resource Relation:
- Conference: 6. workshop on the role of impurities and defects in silicon device processing, Snowmass, CO (United States), 11-14 Aug 1996; Other Information: PBD: [1996]
- Country of Publication:
- United States
- Language:
- English
Similar Records
Self-aligned selective-emitter plasma-etchback and passivation process for screen-printed silicon solar cells
Plasma texturing, etching and passivation of multicrystalline silicon solar cells