Effectiveness of hydrogen dilution for designing amorphous to crystalline Si thin film in inductively coupled plasma assisted magnetron sputtering

Shin, Ki Soon; Sahu, Bibhuti Bhusan; Han, Jeon G.; Hori, Masaru

doi:10.7567/jjap.54.060303

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…Localized epitaxy and nanocrystalline behavior of the a-Si:H films are known to be detrimental to the passivating property of the films and hence to the overall solar cell performance. Hydrogen dilution and plasma power are known to be factors affecting nanocrystalline behavior , along with substrate temperature. Therefore, we have used Raman spectroscopy as an analysis tool to detect any nanocrystalline fraction (nc-Si) in the a-Si:H film due to HPT.…”

Section: Resultsmentioning

confidence: 99%

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Soman

Nsofor

Das

et al. 2019

ACS Appl. Mater. Interfaces

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Passivation of the interface defect states is crucial to mitigate the recombination losses in silicon solar cells. In this work, we have investigated the role of hydrogen plasma treatment (HPT) to passivate the interfacial defects between crystalline (c-Si) and hydrogenated amorphous silicon (a-Si:H) in silicon heterojunction (SHJ) solar cells. For the first time, we have found a correlation between the dynamic properties of hydrogen plasma and passivation quality of the films by using in situ optical emission spectroscopy and quasi-steady state photoconductance measurement. The optimum condition for saturation of the dangling bonds by HPT has been studied in detail by tuning the excited hydrogen (H) species and ion bombardment energies by controlling physical parameters like plasma current and chamber pressure. We have investigated the role of annealing after HPT to redistribute the H in the post-treated a-Si:H film and have obtained an iV oc of 755 mV, minority carrier lifetime (τ eff ) of 4.6 ms, and SRV of 1.5 cm/s on test structures having only an 10 nm intrinsic a-Si:H layer on textured silicon wafers. The H bond configuration at the interface of a-Si:H and c-Si has been investigated by Fourier transform infrared spectroscopy, which demonstrates improved monohydride bonding in the films after HPT derived from the analysis of microstructure parameter and H concentration values. Raman spectroscopy shows the absence of the nanocrystalline fraction after HPT and verifies reduced coordination defects due to annealing after HPT. The proof of concept has been validated by fabricated SHJ solar cells having a V oc of 729 mV and efficiency of 18.7% after HPT, with the best cell efficiency reaching 20.2% after doped layer optimization. The decrease in reverse saturation current and ideality factor after HPT verifies that the improvement in performance is from reduced recombination losses at the interface due to passivation of defects in midgap states.

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Section: Resultsmentioning

confidence: 99%

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Soman

Nsofor

Das

et al. 2019

ACS Appl. Mater. Interfaces

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“…A low power test signal from a signal generator is supplied to a power amplifier to generate continuous-wave (CW) UHF power up to 300 W. The details of the plasma sources are reported elsewhere. 31,33,36,38 An equal input power of 200 W is applied from both the RF and UHF sources for the Si QD deposition process. At a fixed flow rate of NH 3 (=0.7 sccm), the silane flow rates are varied to change the working pressure from 10 to 50 mTorr for deposition.…”

Section: A Experimental Reactor and Parametersmentioning

confidence: 99%

“…30 The requirement of a high deposition temperature can be reduced considerably by using novel plasma sources by developing alternative plasma concepts. [31][32][33][34] The advances in this area continue to produce solutions by enhancing the plasma generation frequency from low-frequency RF 32,35 and ultra-high frequency (UHF) 33,36 to the microwave range. 37 Recent work, using RF-UHF dual frequency (DF) capacitively coupled plasma (CCP) sources, has shown a very high ionization and dissociation efficiency along with its utility for plasma applications at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Plasma engineering of silicon quantum dots and their properties through energy deposition and chemistry

Sahu

Yin

Gauter

et al. 2016

Phys. Chem. Chem. Phys.

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The characterization of plasma and atomic radical parameters along with the energy influx from plasma to the substrate during plasma enhanced chemical vapor deposition (PECVD) of Si quantum dot (QD) films is presented and discussed. In particular, relating to the Si QD process optimization and control of film growth, the necessity to control the deposition environment by inducing the effect of the energy of the key plasma species is realized. In this contribution, we report dual frequency PECVD processes for the low-temperature and high-rate deposition of Si QDs by chemistry and energy control of the key plasma species. The dual frequency plasmas can effectively produce a very high plasma density and atomic H and N densities, which are found to be crucial for the growth and nucleation of QDs. Apart from the study of plasma chemistry, the crucial role of the energy imparted due to these plasma activated species on the substrate is determined in light of QD formation. Various plasma diagnostics and film analysis methods are integrated to correlate the effect of plasma and energy flux on the properties of the deposited films prepared in the reactive mixtures of SiH/NH at various pressures. The present results are highly relevant to the development of the next-generation plasma process for devices that rely on effective control of the QD size and film properties.

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Influence of excitation frequency and electrode separation on the growth of microcrystalline silicon films and their application in single junction microcrystalline solar cell

Das

Mandal

Dhar

et al. 2017

J Mater Sci: Mater Electron

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Effectiveness of hydrogen dilution for designing amorphous to crystalline Si thin film in inductively coupled plasma assisted magnetron sputtering

Cited by 8 publications

References 25 publications

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Correlation between in Situ Diagnostics of the Hydrogen Plasma and the Interface Passivation Quality of Hydrogen Plasma Post-Treated a-Si:H in Silicon Heterojunction Solar Cells

Plasma engineering of silicon quantum dots and their properties through energy deposition and chemistry

Influence of excitation frequency and electrode separation on the growth of microcrystalline silicon films and their application in single junction microcrystalline solar cell

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