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.
Photovoltaics, now a billion-dollar industry, is experiencing staggering growth as increased conc... more Photovoltaics, now a billion-dollar industry, is experiencing staggering growth as increased concerns over fuel supply and carbon emissions have encouraged governments and environmentalists to become increasingly prepared to offset the extra cost of solar energy.
Photovoltaics is now a billion dollar industry is experiencing staggering growth as increased con... more Photovoltaics is now a billion dollar industry is experiencing staggering growth as increased concerns over fuel supply and carbon emissions have encouraged governments and environmentalists to become increasingly prepared to off-set the extra cost of solar energy. Though already significant solar energy will become truly mainstream when it's $/W is comparable to other energy sources, at the moment it is around 4 times too expensive. Three "generations" of photovoltaics have been envisaged that will take solar power into the mainstream.
Photovoltaics is already a billion dollar industry. It is experiencing rapid growth as concerns o... more Photovoltaics is already a billion dollar industry. It is experiencing rapid growth as concerns over fuel supplies and carbon emissions mean that governments and individuals are increasingly prepared to ignore its current high costs. It will become truly mainstream when its costs are comparable to other energy sources. At the moment, it is around four times too expensive for competitive commercial production. Three generations of photovoltaics have been envisaged that will take solar power into the mainstream. Currently, photovoltaic production is 90% first-generation and is based on silicon wafers. These devices are reliable and durable, but half of the cost is the silicon wafer and efficiencies are limited to around 20%. A second generation of solar cells would use cheap semiconductor thin films deposited on low-cost substrates to produce devices of slightly lower efficiency. A number of thin-film device technologies account for around 5-6% of the current market. As second-generation technology reduces the cost of active material, the substrate will eventually be the cost limit and higher efficiency will be needed to maintain the cost-reduction trend. Third-generation devices will use new technologies to produce high-efficiency devices. Advances in nanotechnology, photonics, optical metamaterials, plasmonics and semiconducting polymer sciences offer the prospect of cost-competitive photovoltaics. It is reasonable to expect that cost reductions, a move to second-generation technologies and the implementation of new technologies and third-generation concepts can lead to fully costcompetitive solar energy in 10-15 years.
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.
Photovoltaics, now a billion-dollar industry, is experiencing staggering growth as increased conc... more Photovoltaics, now a billion-dollar industry, is experiencing staggering growth as increased concerns over fuel supply and carbon emissions have encouraged governments and environmentalists to become increasingly prepared to offset the extra cost of solar energy.
Photovoltaics is now a billion dollar industry is experiencing staggering growth as increased con... more Photovoltaics is now a billion dollar industry is experiencing staggering growth as increased concerns over fuel supply and carbon emissions have encouraged governments and environmentalists to become increasingly prepared to off-set the extra cost of solar energy. Though already significant solar energy will become truly mainstream when it's $/W is comparable to other energy sources, at the moment it is around 4 times too expensive. Three "generations" of photovoltaics have been envisaged that will take solar power into the mainstream.
Photovoltaics is already a billion dollar industry. It is experiencing rapid growth as concerns o... more Photovoltaics is already a billion dollar industry. It is experiencing rapid growth as concerns over fuel supplies and carbon emissions mean that governments and individuals are increasingly prepared to ignore its current high costs. It will become truly mainstream when its costs are comparable to other energy sources. At the moment, it is around four times too expensive for competitive commercial production. Three generations of photovoltaics have been envisaged that will take solar power into the mainstream. Currently, photovoltaic production is 90% first-generation and is based on silicon wafers. These devices are reliable and durable, but half of the cost is the silicon wafer and efficiencies are limited to around 20%. A second generation of solar cells would use cheap semiconductor thin films deposited on low-cost substrates to produce devices of slightly lower efficiency. A number of thin-film device technologies account for around 5-6% of the current market. As second-generation technology reduces the cost of active material, the substrate will eventually be the cost limit and higher efficiency will be needed to maintain the cost-reduction trend. Third-generation devices will use new technologies to produce high-efficiency devices. Advances in nanotechnology, photonics, optical metamaterials, plasmonics and semiconducting polymer sciences offer the prospect of cost-competitive photovoltaics. It is reasonable to expect that cost reductions, a move to second-generation technologies and the implementation of new technologies and third-generation concepts can lead to fully costcompetitive solar energy in 10-15 years.
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.
Uploads
Papers by Matt Boreland