Black silicon photovoltaics

Abstract

35 words): An overview and comparison of different fabrication methods of black silicon is presented. Guidelines to optimize relevant parameters such as spatial frequencies and surface defect densities for optoelectronic applications such as photovoltaics will be given. Summary:The potential of silicon surfaces structured in the micro-and nanometer regime are widely known, e.g. in photovoltaic (PV) crystalline silicon (c-Si) solar cells [1][2], watersplitting by photo-electrochemical-catalysis (PEC) [3], phododiods [4], terahertz emitters[5], highly sensitive optical[6] and chemical detection devices [7], amongst many others. Black silicon offers extraordinary and broadband antireflection properties [8]. Additionally, strong randomizing light-trapping is achieved for weakly absorbed photons close to the band edge of c-Si, i.e. light trapping [9]. The enlarged area for 3-D structured p/n-junctions might be advantageous for charge carrier separation. But due to the strongly enlarged surface and a usually high surface defect density black silicon nanostructures exhibit rather low electronic surface quality leading to strong surface recombination. This drawback limits the performance of potential devices [10], [11]. Therefore, effective surface passivation is essential for nanostructured silicon and investigations to find a well suited passivation scheme are going on ever since b-Si has been used for electro-optical devices. In this work, different black silicon fabrication methods are compared. Investigated are the resulting morphologies, as well as optical and electronic properties. Different groups working on black silicon have cooperated for this study. As benchmark parameters, we used the optical absorption and the minority carrier lifetime after the passivation of the samples with thermal-atomic layer deposited Al2O3 [12]. The differences of the obtained black silicon samples fabricated by different proceesses, such as plasma etching, chemical etching or laser processing, are discussed. Based on our findings, we will give guidelines to optimize the relevant physical parameters, e.g. the spatial frequencies and the surface defect densities for optoelectronic applications. PTu2C.2.pdf

Black Silicon With Ultra‐Low Surface Recombination Velocity Fabricated by Inductively Coupled Power Plasma

“…For t RIE ≥5 min, R is very similar and lower than 2% in the full measurement range. The measured reflectance is slightly higher than what has been obtained previously using RIE texturing, where values down to less than 1% at normal incidence were obtained. We notice that the wafers used for this study are double‐side mirror‐polished, which have an initial higher R than saw‐damaged removed, solar‐grade wafers.…”

“…Extracting S textured from the stabilized lifetime data results in values close to S planar (10.6 cm s −1 ) only for t RIE of 1.5 and 2 min (12.9 and 13.6 cm s −1 , respectively). We note that texturing with ICP for 3 min or shorter times in our equipment results in S textured values (before degradation) on par with or even better than the state‐of‐the‐art for p‐type CZ (11 cm s −1 in the review by Otto et al, 20 cm s −1 in the record b‐Si cells by Savin et al and 10 cm s −1 reported by Allen et al). This indicates potential for further efficiency improvements of b‐Si solar cells made by RIE texturing, if CCP is omitted from the texturing process.…”

Black silicon back‐contact module with wide light acceptance angle

“…3 Black silicon surfaces can be achieved using different techniques that can be easily incorporated in the PV industry such as metalassisted wet-chemical etching (MACE), dry reactive ion etching (RIE), inductive couple plasma-reactive ion etching (ICP-RIE), laser structuring, and electrochemical etching. 4 Additionally, collateral benefits of b-Si have arisen recently improving low-cost substrates by removing saw surface damage in diamond-wire-sawn (DWS) wafers 5 or increasing the gettering effect during doping diffusion on Czochralski (CZ) c-Si solar cells. 6 All these advantages make black silicon etching a very attractive candidate to replace conventional acidic and alkaline texturizing approaches in the PV fabrication chain.…”

High Speed and Stable Solution‐Processed Triple Cation Perovskite Photodetectors

“…Currently, commercial photodetectors (PDs) are mainly made from the inorganic semiconductor materials, including Si, ZnO, GaN, and InGaAs . These devices show fast response and high responsivity due to their outstanding electrical and optical properties.…”