We report on the attainment of high quality surface passivation of crystalline silicon using facile native oxide and plasma enhanced chemical vapour deposition SiNx. Using systematic measurements of excess carrier density dependent minority carrier lifetime, it is observed that the inferred interface defect density decreases with increasing native oxide thickness while the interface charge density remains unchanged with thickness, which ranges from 0.2 Å to 10 Å. A surface recombination velocity of 8 cm/s is attained corresponding to a native oxide layer thickness of ∼10 Å. Similar chemically grown oxide layer followed by SiNx deposition is shown to yield comparable passivation, indicating practical viability of the passivation scheme.
This article reports on the integration of facile native oxide-based passivation of crystalline silicon surfaces within the back amorphous-crystalline silicon heterojunction solar cell concept. The new passivation scheme consists of 1-nm thick native oxide and nominally 70-nm thick PECVD silicon nitride. The low temperature passivation scheme provides uniform high quality surface passivation and low parasitic optical absorption. The interdigitated doped hydrogenated amorphous silicon layers were deposited on the rear side of the silicon wafer using the direct current saddle field PECVD technique. A systematic analysis of a series of back amorphous-crystalline silicon heterojunction cells is carried out in order to examine the influence of the various cell parameters (interdigital gap, n-doped region width, ratio of widths of p, and n-doped regions) on cell performance. A photovoltaic conversion efficiency of 16.7% is obtained for an untextured cell illuminated under AM 1.5 global spectrum (cell parameters: V OC of 641 mV, J SC of 33.7 mA-cm -2 and fill factor of 77.3%). Copyright
We report on the use of conventional non-Bosch, non-cryogenic Reactive Ion Etching (RIE) processing to produce a range of low optical reflection morphologies on <100> silicon wafer. Tapered structures and nano dendritic-pillars are patterned into silicon over a pressure range of 550 - 700 mTorr at various run times. Low pressure RIE conditions yield tapered profiles while at higher pressures nano-pillars are produced. The optimized condition of 650 mTorr for 20-30 minutes yields uniform distribution of nano dendritic pillars resulting in a low average reflectance of 4.2% – without an additional antireflective coating. A simple kinetic Monte-Carlo model shows that nano-dendritic structures can be formed due to low etching rate of side walls and evolve into tapered structures over a longer run time. Refractive index profiles built from our simulated patterns and surface morphology of the samples yield calculated reflectance curves that correlate well with experimental results.
The two photon absorption (TPA) process is currently used to write high resolution microstructures for a variety of applications. Key parameters required to predict the final structure formation for this process are experimentally determined and reported in this article for two commercially available resists, Ormocore and SU-8. The measured TPA coefficients measured at 800 nm for Ormocore and SU-8 are 27 ± 6 and 28 ± 6 cm TW -1 , respectively. For Ormocore and SU-8 the dose required to write 35 and 50 lm high structures, respectively, were 54 ± 8 and 3.5 ± 0.5 J cm -3 , respectively, and the measured contrasts were 15 ± 2 lm per decade J -1 cm 3 and 55 ± 8 lm per decade J -1 cm 3 , respectively.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.