The use of aluminium precursor films has already been shown to enhance the as-deposited grain siz... more The use of aluminium precursor films has already been shown to enhance the as-deposited grain size of silicon films on quartz substrates as grown by electron beam excited plasma chemical vapour deposition (EBEP-CVD). In this paper, the process is successfully migrated from quartz substrates to Corning 1737, low cost glass. The move to low cost substrates is essential for the viability of the process in producing silicon films suitable for low cost photovoltaics. Thin aluminium layers are evaporated onto Corning 1737 substrates prior to EBEP-CVD deposition of silicon at 400-600°C. Subsequent analysis by X-ray diffraction shows increases in as-deposited grain sizes up to 40 nm, exceeding results achieved on quartz; without aluminium the as-deposited grain size is around 5 nm. The grain size enhancement is dependant on the silicon deposition temperature and the substrate cleaning regime. There is also an apparent correlation between the silicon aluminium grain sizes
Journal of Materials Science-materials in Electronics, 2008
Silicon nitride (SiNx ) thin films have been deposited by a new remote plasma deposition system H... more Silicon nitride (SiNx ) thin films have been deposited by a new remote plasma deposition system HiTUS (High Target Utilisation Sputtering). The remote plasma geometry allows, pseudo separation of plasma/target-bias parameters, lower ion bombardment, and effectively eliminates poisoning, making it an attractive option for stable reactive sputtering of important electronic and photovoltaic films including silicon nitride. Transmission and absorbance measurements on glass were performed in order to evaluate the absorbance of the silicon nitride thin layer. The SiNx is produced by reactive sputtering from a silicon target in an Ar/N2 atmosphere, negating the use of silane gas in difference to the more commonly used PECVD method. A deposition rates up to 0.7 nm/s have been obtained. Control of refractive index from 1.9 to 2.3 was achieved by varying the RF target bias, meeting the requirements for silicon passivation in PV applications, with a growth rate independent of refractive index across a wide range. The carrier life time over a range of specified minority carrier densities was measured using a contactless inductively coupled photoconductance tester for 50 ohm cm 〈100〉 oriented silicon wafers coated with different types of SiNx . We found that the passivation action of the silicon nitride increased the carrier lifetime over one order of magnitude.
Through-the-glass laser crystallisation of a-Si, on low-temperature glass, has been achieved for ... more Through-the-glass laser crystallisation of a-Si, on low-temperature glass, has been achieved for the first time using a copper vapour laser (CVL). The CVL's 578/511nm output has minimal absorption in the substrate, thus allowing a simple double-sided irradiation regime. Raman spectroscopy showed that double-sided irradiation is more effective at producing full depth crystallisation, and incrementally increases the crystallisation depth with each pulse. A step-wise crystallisation concept is also introduced to explain the incremental crystallisation behaviour. Additionally, grain sizes were maintained without the need for substrate heating. These factors enhance the CVL's potential to simplify producing PV materials via laser crystallisation.
The use of aluminium precursor films has already been shown to enhance the as-deposited grain siz... more The use of aluminium precursor films has already been shown to enhance the as-deposited grain size of silicon films on quartz substrates as grown by electron beam excited plasma chemical vapour deposition (EBEP-CVD). In this paper, the process is successfully migrated from quartz substrates to Corning 1737, low cost glass. The move to low cost substrates is essential for the viability of the process in producing silicon films suitable for low cost photovoltaics. Thin aluminium layers are evaporated onto Corning 1737 substrates prior to EBEP-CVD deposition of silicon at 400-600°C. Subsequent analysis by X-ray diffraction shows increases in as-deposited grain sizes up to 40 nm, exceeding results achieved on quartz; without aluminium the as-deposited grain size is around 5 nm. The grain size enhancement is dependant on the silicon deposition temperature and the substrate cleaning regime. There is also an apparent correlation between the silicon aluminium grain sizes
Journal of Materials Science-materials in Electronics, 2008
Silicon nitride (SiNx ) thin films have been deposited by a new remote plasma deposition system H... more Silicon nitride (SiNx ) thin films have been deposited by a new remote plasma deposition system HiTUS (High Target Utilisation Sputtering). The remote plasma geometry allows, pseudo separation of plasma/target-bias parameters, lower ion bombardment, and effectively eliminates poisoning, making it an attractive option for stable reactive sputtering of important electronic and photovoltaic films including silicon nitride. Transmission and absorbance measurements on glass were performed in order to evaluate the absorbance of the silicon nitride thin layer. The SiNx is produced by reactive sputtering from a silicon target in an Ar/N2 atmosphere, negating the use of silane gas in difference to the more commonly used PECVD method. A deposition rates up to 0.7 nm/s have been obtained. Control of refractive index from 1.9 to 2.3 was achieved by varying the RF target bias, meeting the requirements for silicon passivation in PV applications, with a growth rate independent of refractive index across a wide range. The carrier life time over a range of specified minority carrier densities was measured using a contactless inductively coupled photoconductance tester for 50 ohm cm 〈100〉 oriented silicon wafers coated with different types of SiNx . We found that the passivation action of the silicon nitride increased the carrier lifetime over one order of magnitude.
Through-the-glass laser crystallisation of a-Si, on low-temperature glass, has been achieved for ... more Through-the-glass laser crystallisation of a-Si, on low-temperature glass, has been achieved for the first time using a copper vapour laser (CVL). The CVL's 578/511nm output has minimal absorption in the substrate, thus allowing a simple double-sided irradiation regime. Raman spectroscopy showed that double-sided irradiation is more effective at producing full depth crystallisation, and incrementally increases the crystallisation depth with each pulse. A step-wise crystallisation concept is also introduced to explain the incremental crystallisation behaviour. Additionally, grain sizes were maintained without the need for substrate heating. These factors enhance the CVL's potential to simplify producing PV materials via laser crystallisation.
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Papers by Matt Boreland