Control of Nanocrystalline Growth Phase and Deposition Rate through Voltage Waveform Tailoring

International audienc

Tailored Voltage Waveforms for the Deposition of Microcrystalline Silicon

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Microcrystalline silicon solar cells deposited using a plasma process excited by tailored voltage waveforms

International audienceThin film solar cells in a p-i-n structure with an absorbing layer of intrinsic hydrogenated microcrystalline silicon (μc-Si:H) deposited through plasma enhanced chemical vapour deposition excited by tailored voltage waveforms have been prepared. The use of an asymmetric voltage waveform decouples the ion-bombardment energy at the growth surface from the injected power and allows the growth of good quality μc-Si:H at reasonable deposition rates (3 Å/s) using low pressure, powder-free conditions. Unoptimized photovoltaic devices with an efficiency of 6.1% are demonstrated using an i-layer deposited at 1.3 Å/s and a process pressure of 500 mTorr

Plasma deposition of nanocrystalline silicon for solar cells : RF waveform tailoring to optimize deposition rate and film morphology

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Tailored Voltage Waveform Capacitively-Coupled Plasmas for IEDF and electron density control: Application to Microcrystalline Si Deposition

International audienceOra

Hydrogenated microcrystalline silicon thin films deposited by RF-PECVD under low ion bombardment energy using voltage waveform tailoring

International audienceWe present experimental results for hydrogenated amorphous and microcrystalline silicon (a-Si:H and μc-Si:H) thin films deposited by PECVD while using a voltage waveform tailoring (VWT) technique to create an electrical asymmetry in the reactor. VWT dramatically modifies the mean ion bombardment energy (IBE) during growth, and we show that for a constant peak-to-peak excitation voltage (VPP), waveforms resembling peaks or valleys result in very different material properties. Using Raman scattering spectroscopy, we show that the crystallinity of the material depends strongly on the IBE, as controlled by VWT. A detailed examination of the Raman scattering spectra reveals that the narrow peak at 520 cm− 1 is disproportionately enhanced by lowering the IBE through the VWT technique. We examine this effect for a range of process parameters, varying the pressure, hydrogensilane dilution ratio, and total flow of H2. In addition, the Sisingle bondHX bonding in silicon thin films deposited using VWT is characterised for the first time, showing that the hydrogen bonding character is changed by the IBE. These results demonstrate the potential for VWT in controlling the IBE during thin film growth, thus ensuring that application-appropriate film densities and crystallinities are achieved, independent of the injected RF power

Plasma Excitation using Tailored Voltage Waveforms for the Deposition of Thin Film Silicon for Photovoltaics: From Plasma Physics to Devices

International audienc

DEPOSITION OF THIN FILM OF SILICON MICROCRISTALLINE BY RADIO FREQUENCY VOLTAGE WAVEFORM TAILORING

International audienc

Plasma deposition processes excited using Tailored Voltage Waveforms: from microcrystalline silicon thin films to devices

International audienc

Tailored Voltage Waveform Capacitively-Coupled Plasmas

International audienc