Journal article
Low surface damage dry etched black silicon
Department of Micro- and Nanotechnology, Technical University of Denmark1
Anhalt University of Applied Sciences2
Silicon Microtechnology, Department of Micro- and Nanotechnology, Technical University of Denmark3
DTU Danchip, Technical University of Denmark4
Fraunhofer Center for Silicon Photovoltaics5
Nanoprobes, Department of Micro- and Nanotechnology, Technical University of Denmark6
Department of Energy Conversion and Storage, Technical University of Denmark7
Black silicon (bSi) is promising for integration into silicon solar cell fabrication flow due to its excellent light trapping and low reflectance, and a continuously improving passivation. However, intensive ion bombardment during the reactive ion etching used to fabricate bSi induces surface damage that causes significant recombination.
Here, we present a process optimization strategy for bSi, where surface damage is reduced and surface passivation is improved while excellent light trapping and low reflectance are maintained. We demonstrate that reduction of the capacitively coupled plasma power, during reactive ion etching at non-cryogenic temperature (-20°C), preserves the reflectivity below 1% and improves the effective minority carrier lifetime due to reduced ion energy.
We investigate the effect of the etching process on the surface morphology, light trapping, reflectance, transmittance, and effective lifetime of bSi. Additional surface passivation using atomic layer deposition of Al2O3 significantly improves the effective lifetime. For n-type wafers, the lifetime reaches 12 ms for polished and 7.5 ms for bSi surfaces.
For p-type wafers, the lifetime reaches 800 ls for both polished and bSi surfaces.
Language: | English |
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Publisher: | AIP Publishing LLC |
Year: | 2017 |
Pages: | 143101 |
ISSN: | 10897550 and 00218979 |
Types: | Journal article |
DOI: | 10.1063/1.4993425 |
ORCIDs: | Davidsen, Rasmus Schmidt , Plakhotnyuk, Maksym M. , 0000-0001-7973-678X , Stamate, Eugen , Hansen, Ole and Michael-Lindhard, Jonas |