Fully Bottom‐Up Waste‐Free Growth of Ultrathin Silicon Wafer via Self‐Releasing Seed Layer

Hong, Jong Ha; Lee, Yong-Hwan; Mo, Sung-In; Jeong, Hye-Won; An, Jeong-Ho; Song, Hee‐eun; Oh, Jihun; Bang, Junhyeok; Oh, Joon Ho; Kim, Ka‐Hyun

doi:10.1002/adma.202103708

Cited by 13 publications

(10 citation statements)

References 40 publications

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“…At the end of this process, surface oxides were removed by dipping the wafers in a diluted hydrofluoric acid (HF, 5%) solution for 45 s. These wafers were then immediately transferred to the vacuum chamber, and the wafers were passivated on both sides by an i-layer (hereafter, I) using radio frequency (RF, 13.56 MHz) capacitively coupled PECVD using SiH 4 diluted in H 2 . 31 For the doped a-Si:H layers, dopant gases, namely, PH 3 and B 2 H 6 , were added for electron-and hole-passivating contacts, respectively. An I layer was deposited using the following conditions: R({[SiH 4 ]/([H 2 ] + [SiH 4 ])} × 100) = 6.86%, a pressure (P) of 1800 mTorr, interelectrode distance (D i ) of 2 cm, RF power of 50 W, and substrate temperature of 220 °C.…”

Section: Methodsmentioning

confidence: 99%

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Jeong

et al. 2022

ACS Appl. Energy Mater.

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Recent improvements in highly efficient crystalline silicon (c-Si) solar cells have relied on surface passivation. Hydrogen plays a crucial role in the surface passivation of silicon heterojunction (SHJ) solar cells because Si–H bonds passivate dangling bonds in amorphous silicon and on the c-Si surface. In this work, we demonstrate that the Si–H bonding configuration is modified by layer stacking sequence for SHJs. The quality of surface passivation strongly correlates with low-temperature hydrogen effusion from the SHJ structure. Our results show that the deposition of doped layers on intrinsic amorphous silicon supplies additional hydrogen to the amorphous/crystalline heterostructure. Moreover, the deposition of a p-layer modifies the microstructure of the intrinsic layer underneath, whereas depositing an n-layer does not induce structural changes. We suggest that the low-temperature hydrogen effusion characteristics can be used as a sensitive indicator for examining the passivation quality of SHJ solar cells.

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Section: Methodsmentioning

confidence: 99%

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Jeong

et al. 2022

ACS Appl. Energy Mater.

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“…Interestingly, PECVD‐induced surface porosity can be further transformed into nanogaps with a post hydrogen annealing at 900 °C for 10 min, [ 40 ] as shown in Figure . The key point of this method is to use plasma‐epitaxial Si as the self‐releasing seed layer of a high‐temperature epitaxial (HTE) film of high quality deposited at a higher rate than in the case of low‐temperature epitaxy.…”

Section: “Bottom‐up” Approachesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The efficiency of c‐Si solar cells (50 μm) produced by plasma‐assisted epitaxy growth and subsequent hydrogen annealing to form a self‐organizing nanogap which allows to detach the epitaxial layer from the parent substrate is 11.4%. [ 40 ] Solar cells with a 40 μm c‐Si absorber produced from the epitaxial process based on porous Si developed by Brendel [ 41,42 ] have reached an efficiency of 20.44%. [ 43 ] The efficiency of epi‐PECVD heterojunction c‐Si solar cells on glass by anodic bonding and mechanical cleavage is 7.3%, and the J sc produced by ultra‐thin (5.5 μm) epitaxial layers is 21.5 mA cm −2 .…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of Crystalline Si Thin Films for Photovoltaics

Shen

Cabarrocas

et al. 2022

Physica Rapid Research Ltrs

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Crystalline Si (c‐Si) thin films have been widely studied for their application to solar cells and flexible electronics. However, their application at large scale is limited by their fabrication process. As reviewed in this paper, many approaches have been studied, but only some of them have been made into large‐scale industrial production. The standard wire sawing of Si ingots cannot be scaled down to produce thin c‐Si wafers and films due to the brittle nature of c‐Si material, the resulting significant thickness variations, and the waste of material. Therefore, techniques based on the kerf‐less processes including “top‐down” and “bottom‐up” approaches have been developed in recent decades. In this review, photovoltaic applications of thin c‐Si wafers with thicknesses ranging from 50 μm down to 1 μm are presented first. Then, methods to fabricate c‐Si thin films based on both approaches are detailed, including slim‐cut, “smart‐cut,” epi‐free, as well as various growth processes such as molecular beam epitaxy, liquid phase epitaxy, ion beam, and chemical vapor deposition processes at a wide range of growth temperatures, from 1000 °C down to 150 °C. The advantages and disadvantages of these methods are presented and compared.

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“…On the other hand, epitaxial Silicon (epi-Si) films are receiving increased attention for the fabrication of novel devices, where c-Si films can be grown or etched in a selective way to produce 3D structures on the surface of the c-Si wafer, in addition to the production of ultrathin c-Si films [16][17][18] on foreign substrates [19], and epi-Si on metallic surfaces [20,21], crystalline semiconductors surfaces such as (100) c-Si [22] and gallium arsenide (c-GaAs) [23]. Moreover, the crystallization process using PECVD, which has been discussed in terms of the impact of silicon clusters [24] opens the possibility to produce novel devices at low substrate temperatures.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study on the Quality of Microcrystalline and Epitaxial Silicon Films Produced by PECVD Using Identical SiF4 Based Process Conditions

et al. 2021

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Hydrogenated microcrystalline silicon (µc-Si:H) and epitaxial silicon (epi-Si) films have been produced from SiF4, H2 and Ar mixtures by plasma enhanced chemical vapor deposition (PECVD) at 200 °C. Here, both films were produced using identical deposition conditions, to determine if the conditions for producing µc-Si with the largest crystalline fraction (XC), will also result in epi-Si films that encompass the best quality and largest crystalline silicon (c-Si) fraction. Both characteristics are of importance for the development of thin film transistors (TFTs), thin film solar cells and novel 3D devices since epi-Si films can be grown or etched in a selective manner. Therefore, we have distinguished that the H2/SiF4 ratio affects the XC of µc-Si, the c-Si fraction in epi-Si films, and the structure of the epi-Si/c-Si interface. Raman and UV-Vis ellipsometry were used to evaluate the crystalline volume fraction (Xc) and composition of the deposited layers, while the structure of the films were inspected by high resolution transmission electron microscopy (HRTEM). Notably, the conditions for producing µc-Si with the largest XC are different in comparison to the fabrication conditions of epi-Si films with the best quality and largest c-Si fraction.

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Fully Bottom‐Up Waste‐Free Growth of Ultrathin Silicon Wafer via Self‐Releasing Seed Layer

Cited by 13 publications

References 40 publications

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Fabrication of Crystalline Si Thin Films for Photovoltaics

Comparative Study on the Quality of Microcrystalline and Epitaxial Silicon Films Produced by PECVD Using Identical SiF4 Based Process Conditions

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