Selective Dry Etching of p-Type Si Films for Photolithography Processing of Interdigitated Back Contact Silicon Heterojunction Solar Cells

Kim, Do Yun; Lentz, Florian; Liu, Yong; Singh, Aryak; Richter, Alexei; Pomaska, Manuel; Lambertz, Andreas; Ding, Kaining

doi:10.1109/jphotov.2017.2719866

Cited by 5 publications

(8 citation statements)

References 42 publications

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“…In this approach, etching of the underlying a‐Si:H stack is needed, and hence, it is a subtractive route, just like in photolithography. Often, wet etching is used, which is not well‐controllable and can lead to processing issues . Dry etching can considerably improve process reliability…”

Section: Introductionmentioning

confidence: 95%

“…Another popular “litho‐free” alternative to patterning, which is contact‐less and also drastically reduces the number wet chemical steps, is laser ablation‐assisted patterning . In this approach, the pattern is often directly structured onto a sacrificial mask layer on top of the a‐Si:H stack to be patterned.…”

Section: Introductionmentioning

confidence: 99%

“…14 Another popular "litho-free" alternative to patterning, which is contact-less and also drastically reduces the number wet chemical steps, is laser ablation-assisted patterning. [15][16][17][18][19][20] In this approach, the pattern is often directly structured onto a sacrificial mask layer on top of the a-Si:H stack to be patterned. While there is a risk of laser-induced thermal damage to the crystalline silicon and the heterocontact in the laser-ablated areas, 19,20 significant strides have been made recently in tackling this issue.…”

Section: Introductionmentioning

confidence: 99%

“…Often, wet etching is used, which is not well-controllable and can lead to processing issues. 18,21,22 Dry etching can considerably improve process reliability. 21 One of the strategies to simplify our baseline process sequence (depicted in Figure 1, left) into a simpler one that is litho-free, almost alldry, and inexpensive is shown in Figure 1 (middle).…”

Section: Introductionmentioning

confidence: 99%

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A novel silicon heterojunction IBC process flow using partial etching of doped a‐Si:H to switch from hole contact to electron contact in situ with efficiencies close to 23%

Radhakrishnan

Uddin

et al. 2019

Progress in Photovoltaics

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We present a novel process sequence to simplify the rear‐side patterning of the silicon heterojunction interdigitated back contact (HJ IBC) cells. In this approach, interdigitated strips of a‐Si:H (i/p+) hole contact and a‐Si:H (i/n+) electron contact are achieved by partially etching a blanket a‐Si:H (i/p+) stack through an SiOx hard mask to remove only the p+ a‐Si:H layer and replace it with an n+ a‐Si:H layer, thereby switching from a hole contact to an electron contact in situ, without having to remove the entire passivation. This eliminates the ex situ wet clean after dry etching and also prevents re‐exposure of the crystalline silicon surface during rear‐side processing. Using a well‐controlled process, high‐quality passivation is maintained throughout the rear‐side process sequence leading to high open‐circuit voltages (VOC). A slightly higher contact resistance at the electron contact leads to a slightly higher fill factor (FF) loss due to series resistance for cells from the partial etch route, but the FF loss due to J02‐type recombination is lower, compared with reference cells. As a result, the best cell from the partial etch route has an efficiency of 22.9% and a VOC of 729 mV, nearly identical to the best reference cell, demonstrating that the developed partial etch process can be successfully implemented to achieve cell performance comparable with reference, but with a simpler, cheaper, and faster process sequence.

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Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A novel silicon heterojunction IBC process flow using partial etching of doped a‐Si:H to switch from hole contact to electron contact in situ with efficiencies close to 23%

Radhakrishnan

Uddin

et al. 2019

Progress in Photovoltaics

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“…A variety of methods have been used and proposed including shadow masking, photolithography and others. 6,7 These methods may be difficult to industrialize due to difficulties in alignment or cost limitations. One method proposed to simplify IBC patterning has been proposed by Tomasi et al by introducing a tunnel junction concept for the BSF fingers of the solar cell.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced BSF: A new approach to simplify IBC-SHJ solar cell fabrication

Vasudevan¹,

Harrison²,

d'Alonzo³

et al. 2018

AIP Conference Proceedings

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Abstract. Silicon heterojunction (SHJ) interdigitated back-contacted (IBC) solar cells currently hold the world record for conversion efficiency of silicon based, single junction solar cells. In order to use this technology for industrial applications, cost-effective strategies for amorphous silicon (a-Si:H) patterning of the back surface field (BSF) and emitter have to be developed. We propose a process flow that eliminates the need to align a-Si:H deposition steps. This is accomplished by the use of a low power, ultraviolet laser to transform an i-n-i-p a-Si:H layer stack into a fully working BSF. This process is referred to here as compensation lasering. In this manuscript, we first show a proof of concept of the compensation laser process using front and rear contacted SHJ solar cells. We then use Raman and SIMS characterization to show that the laser affects boron concentration to form a working BSF. Finally, we present precursors of a SHJ-IBC. Implied VOC values of 732 mV have been achieved showing the potential of this technique as an SHJ-IBC process.

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Evaluating the Practical Efficiency Limit of Silicon Heterojunction–Interdigitated Back Contact Solar Cells by Creating Digital Twins of Silicon Heterojunction Solar Cells with Amorphous Silicon and Nanocrystalline Silicon Hole Contact Layers

Sun,

Kang,

et al. 2024

Physica Status Solidi (a)

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Improving power conversion efficiency (PCE) in photovoltaics has driven innovative approaches in solar cell design and technology. Silicon heterojunction (SHJ) solar cells exhibit advantages in PCE due to their effective passivating contact structures. SHJ–interdigitated back contact (SHJ–IBC) solar cells have the potential to surpass traditional SHJ cells, attributed to their advantage in short‐circuit current (JSC). Herein, Silvaco Atlas technology computer‐aided design is used to create digital twins of high‐efficiency SHJ solar cells with amorphous silicon and nanocrystalline silicon hole selective contact (HSC) layers. Using parameters from digital twins of SHJ solar cells, the practical efficiency limit of SHJ–IBC solar cells is assessed. The results show that SHJ–IBC cells can achieve potential efficiencies of 27.01% with amorphous HSC and 27.38% with nanocrystalline HSC. Further efficiency augmentation to 27.51% can be achieved by narrowing the gap from 80 to 20 μm. This study not only advances comprehension of SHJ–IBC solar cells but also provides insights into optimizing geometrical configurations for improved performance. The utilization of digital twins provides a valuable tool for predicting and evaluating the performance of SHJ–IBC solar cells, contributing substantively to the ongoing development of high‐efficiency photovoltaic technology.

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Selective Dry Etching of p-Type Si Films for Photolithography Processing of Interdigitated Back Contact Silicon Heterojunction Solar Cells

Cited by 5 publications

References 42 publications

A novel silicon heterojunction IBC process flow using partial etching of doped a‐Si:H to switch from hole contact to electron contact in situ with efficiencies close to 23%

A novel silicon heterojunction IBC process flow using partial etching of doped a‐Si:H to switch from hole contact to electron contact in situ with efficiencies close to 23%

Laser-induced BSF: A new approach to simplify IBC-SHJ solar cell fabrication

Evaluating the Practical Efficiency Limit of Silicon Heterojunction–Interdigitated Back Contact Solar Cells by Creating Digital Twins of Silicon Heterojunction Solar Cells with Amorphous Silicon and Nanocrystalline Silicon Hole Contact Layers

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