"Forming Random-nanopores by Optimized 2-step Metal Assisted Etching Process" and "Humidity Degradation and Repair of ALD Al2O3 Passivated Silicon"
Teck Kong Chong and Wensheng Liang (Centre for Sustainable Energy Systems)
SOLAR SEMINAR SERIESDATE: 2013-06-13
TIME: 16:00:00 - 17:00:00
LOCATION: Ian Ross Seminar Room
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ABSTRACT:
Teck Kong Chong
Title: Forming Random-nanopores by Optimized 2-step Metal Assisted Etching Process
Abstract: We present a unique, reliable and cost effective 2-step metal-assisted-etching (MAE) texturing technique that forms random-nanopores. We demonstrate that the random-nanopore morphology is capable of suppressing front surface reflection more efficiently than not only the conventional acidic texturing but also the widely used random pyramid texture. We demonstrate that the angular reflectance distribution of our random-nanopores is intermediate between isotexture and random upright pyramid structures. We also have experimentally proved that random-nanopore texture indeed can outperform isotexture and random upright pyramid morphology when encapsulated. The uniformity and reproducibility of the morphology have also been verified. Due to its nano-scale feature size, it can be used for texturing both mono-crystalline (c-si) and multicrystalline (mc-si) silicon solar cells, thin film solar cells as well as the non-conventional solar cells such as SLIVER cells.
Wensheng Liang
Title: Humidity Degradation and Repair of ALD Al_2 O_3 Passivated Silicon
Abstract: The effect of humidity on boron diffused and undiffused silicon samples passivated by aluminum oxide (Al2O3) synthesized by atomic layer deposition (ALD) has been investigated. The passivation performance of single Al2O3 layers degrades apparently after 30-minute exposure in humidity at temperature 50a and above, which is much more quickly than samples passivated by thermal SiOx. It was found that, for boron diffused samples, the degradation rate is closely related with the ambient temperature, and the degradation is very slow if the ambient temperature is less than 50a.PECVD SiNx capping layers can efficiently act as a protection layer for Al2O3 to resist a damp-heat condition of 100% relatively humidity at 80. We experimentally demonstrate that the degraded passivation of a Al2O3 layer can be healed by light illumination, negative corona charge deposition and N2 anneal in low temperature. The observed behavior is under investigation and will be discussed more fully in the final version.
BIO:
Wensheng Liang received his B.Eng., M.Eng. from Northeastern University located in Shenyang, China. Now he is a PhD student in CSES doing research about solar cell surface passivation by ALD(Atomic Layer Deposition) Al2O3.
