Organic passivation of silicon through multifunctional polymeric interfaces

Castillo, Mariela Lizet; Ugur, Asli; Sojoudi, Hossein; Nakamura, Nathan; Liu, Zhe; Lin, Fen; Brandt, Riley E.; Buonassisi, Tonio; Reeja‐Jayan, B.; Gleason, Karen K.

doi:10.1016/j.solmat.2016.10.050

Cited by 5 publications

(5 citation statements)

References 35 publications

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“…Yang et al and Castillo et al have examined the passivation capabilities of room temperature deposited/formed multifunctional polymeric films using chemical vapor deposition (CVD). While good passivation ( S < 10 cm s −1 ) has been achieved by this method, the use of a CVD system is not attractive for low cost and straightforward passivation.…”

Section: Types Of Temporary Surface Passivationmentioning

confidence: 99%

Temporary Surface Passivation for Characterisation of Bulk Defects in Silicon: A Review

Grant

Murphy

2017

Physica Rapid Research Ltrs

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Accurate measurements of the bulk minority carrier lifetime in high-quality silicon materials is challenging due to the influence of surface recombination. Conventional surface passivation processes such as thermal oxidation or dielectric deposition often modify the bulk lifetime significantly before measurement. Temporary surface passivation processes at room or very low temperatures enable a more accurate measurement of the true bulk lifetime, as they limit thermal reconfiguration of bulk defects and minimize bulk hydrogenation. In this article we review the state-of-the-art for temporary passivation schemes, including liquid immersion passivation based upon acids, halogen-alcohols and benzyl-alcohols, and thin film passivation usually based on organic substances. We highlight how exceptional surface passivation (surface recombination velocity below 1 cm s À1 ) can be achieved by some types of temporary passivation. From an extensive review of available data in the literature, we find p-type silicon can be best passivated by hydrofluoric acid containing solutions, with superacid-based thin films showing a slight superiority in the n-type case. We review the practical considerations associated with temporary passivation, including sample cleaning, passivation activation, and stability. We highlight examples of how temporary passivation can assist in the development of improved silicon materials for photovoltaic applications, and provide an outlook for the future of the field.

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Section: Types Of Temporary Surface Passivationmentioning

confidence: 99%

Temporary Surface Passivation for Characterisation of Bulk Defects in Silicon: A Review

Grant

Murphy

2017

Physica Rapid Research Ltrs

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“…Organic materials with access to electronics or optoelectronics provide an inexpensive, low-temperature and solution-processing accessible approach. , The anticipated advantage of organic passivation schemes is their potential for low-cost processing. In this regard, for example, Bullock and Grant et al have developed an organic passivation method in which silicon wafers are briefly dipped in a nonaqueous bis(trifluoromethane)sulfonimide superacid solution with a τ eff of ∼8 ms. , Castillo et al have demonstrated a low-temperature (<170 °C) approach using CVD grafting and polymerization processes to passivate the surface of silicon to obtain a τ eff of >2 ms . Other studies have shown that the presence of an organic thin-film [such as [6,6]-phenyl-C 61 -butyric acid methyl ester, 8-hydroxyquinolinolato-lithium, and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)] is essential for suppressing carrier recombination. − Our previous work found that a PSS thin film fabricated by the sol–gel method can passivate Si well, yielding a τ eff of >2 ms on wafers with a resistivity of 1–5 Ω·cm after heat treatment at 130 °C for 10 min …”

Section: Introductionmentioning

confidence: 99%

Vacuum-Free, Room-Temperature Organic Passivation of Silicon: Toward Very Low Recombination of Micro-/Nanotextured Surface Structures

Chen

Zhang

et al. 2018

ACS Appl. Mater. Interfaces

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Crystalline silicon (c-Si) solar cells remain dominant in the photovoltaic (PV) market because of their cost-effective advantages. However, the requirement for expensive vacuum equipment and the power-hungry thermal budget for surface passivation technology, which is one of the key enablers of the high performance of c-Si solar cells, impede further reductions of costs. Thus, the omission of the vacuum and high-temperature process without compromising the passivation effect is highly desirable due to cost concerns. Here, we demonstrate a vacuum-free, room-temperature organic Nafion thin-film passivation scheme with an effective minority carrier lifetime (τ eff ) exceeding 9 ms on an n-type c-Si wafer with a resistivity of 1−5 Ω•cm, corresponding to an implied open circuit voltage (iV oc ) of 724 mV and upper-limit surface recombination velocity (SRV) of 1.46 cm/s, which is a level that is in line with the hydrogenated amorphous Si film-passivation scheme used in the current PV industry. We find that the Nafion film passivation of Si can be enhanced in an O 2 atmosphere and that the Nafion/c-Si interface oxidation should be responsible for the passivation mechanism. This highly effective passivation is also achieved on various micro-/nanotextured Si surface structures from actual production, including a pyramidal surface and nanopore−pyramid hybrid structure with nanopores on the inclined plane of the pyramid. We develop an organic Nafion-passivated n-type back-junction Si solar cell to examine application in a real device. The open circuit voltage (V oc ) of the solar cell with the Nafion passivation layer achieves a clear improvement (30.8 mV) over those without the passivation layer, resulting in an increase (1.5%) in the power conversion efficiency. These results suggest the potential use of these organic electronics with current Si microelectronics and a new strategy for the development of vacuum-free, low-temperature Si-based PVs at low cost.

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“…The mechanism of replacement likely occurs through the abstraction of hydrogen by an initial methyl radical and the reaction with a second methyl radical to form the methylated backbone. Indeed, previous studies have shown that methyl radicals generated from the decomposition of TBPO can abstract hydrogen from the Si–H bond. , …”

Section: Resultsmentioning

confidence: 99%

“…Indeed, previous studies have shown that methyl radicals generated from the decomposition of TBPO can abstract hydrogen from the Si−H bond. 23,24 To test the abstraction hypothesis, reference PS samples from PIKE Technologies were exposed to TBPO vapor at a filament temperature of 330 °C. Figure 3c shows the ATR− FTIR spectra of a treated sample compared with the as-received sample.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Ultrathin and Conformal Initiated Chemical-Vapor-Deposited Layers of Systematically Varied Surface Energy for Controlling the Directed Self-Assembly of Block CoPolymers

et al. 2018

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Directed self-assembly (DSA) of block copolymer (BCP) thin films is a promising approach to enable next-generation patterning at increasingly smaller length scales. DSA utilizes interfacial wetting layers to force the BCP domains to self-assemble with the desired orientation with respect to the substrate. Here, we demonstrate that initiated chemical-vapor-deposited (iCVD) polydivinylbenzene (pDVB) ultrathin films can direct the self-assembly of poly(styrene- block-methylmethacrylate). We found that the methyl radicals formed at increased filament temperatures during the iCVD process result in the backbone methylation of pDVB. By tuning the degree of backbone methylation, we systematically changed the wetting properties of the iCVD pDVB from a slight poly(methylmethacrylate) preference to complete poly(styrene) preference. Additionally, we utilize the conformal nature of the iCVD to form a wetting layer over a topographical line and space pattern, which is subsequently used to produce self-assembled BCP films with both perpendicular orientation and long-range alignment.

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Organic passivation of silicon through multifunctional polymeric interfaces

Cited by 5 publications

References 35 publications

Temporary Surface Passivation for Characterisation of Bulk Defects in Silicon: A Review

Temporary Surface Passivation for Characterisation of Bulk Defects in Silicon: A Review

Vacuum-Free, Room-Temperature Organic Passivation of Silicon: Toward Very Low Recombination of Micro-/Nanotextured Surface Structures

Ultrathin and Conformal Initiated Chemical-Vapor-Deposited Layers of Systematically Varied Surface Energy for Controlling the Directed Self-Assembly of Block CoPolymers

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