Suntech RandD Australia Pty Ltd

Sydney, Australia

Suntech RandD Australia Pty Ltd

Sydney, Australia
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Chowdhury A.,French National Center for Scientific Research | Schneider J.,CSG Solar AG | Schneider J.,Fraunhofer Center for Silicon Photovoltaics | Dore J.,CSG Solar AG | And 3 more authors.
Applied Physics A: Materials Science and Processing | Year: 2012

Thin film polycrystalline silicon films grown on glass substrate were irradiated with an infrared continuous wave laser for defects annealing and/or dopants activation. The samples were uniformly scanned using an attachment with the laser system. Substrate temperature, scan speed and laser power were varied to find suitable laser annealing conditions. The Raman spectroscopy and Suns-V ∞c analysis were carried out to qualify the films quality after laser annealing. A maximum enhancement of the open circuit voltage V ∞c of about 100 mV is obtained after laser annealing of as-grown polysilicon structures. A strong correlation was found between the full width half maximum of the Si crystalline peak and V ∞c. It is interpreted as due to defects annealing as well as to dopants activation in the absorbing silicon layer. The maximum V ∞c reached is 485 mV after laser treatment and plasma hydrogenation, thanks to defects passivation. © 2012 Springer-Verlag.

Qiu Y.,IMEC | Qiu Y.,CAS Shanghai Institute of Microsystem and Information Technology | Kunz O.,Suntech RandD Australia Pty Ltd | Fejfar A.,ASCR Institute of Physics Prague | And 6 more authors.
Solar Energy Materials and Solar Cells | Year: 2014

The hydrogen plasma passivation of thin film polycrystalline silicon (pc-Si) was investigated in conjunction with plasma texturing process to make efficient heterojunction solar cells. The pc-Si layers were first treated using direct and remote hydrogen plasma technologies. The heterojunction solar cells were then fabricated by subsequent deposition of i/n+ a-Si:H. Hydrogenation at high temperature (610 C) results in enhanced dissolution and diffusion of hydrogen in pc-Si by a factor of about 3 and 4, respectively, in comparison with those at low temperature (420 C). The hydrogen atoms in the pc-Si layer mainly bond to the silicon dangling bonds and form complexes with dopant atoms. In addition, platelets defects are generated by the hydrogen plasma in the sub-surface region of pc-Si hydrogenated at 420 C and cause higher saturation current in the space charge region whilst they form in the region deeper than 1 μm at 610 C. Removal of the platelets using SF 6/N2O plasma post-texturing after low-temperature hydrogenation not only enhances the short circuit current but also improves the open circuit voltage and the fill factor simultaneously. Combining plasma pre-texturing with high-temperature hydrogenation, the best 2 μm-thick pc-Si heterojunction solar cell reaches an efficiency of 8.54%. © 2013 Elsevier Ltd. All rights reserved.

Dore J.,University of New South Wales | Dore J.,Suntech R and D Australia Pty. Ltd. | Evans R.,Suntech R and D Australia Pty. Ltd. | Eggleston B.D.,University of New South Wales | And 3 more authors.
Materials Research Society Symposium Proceedings | Year: 2012

Intermediate layers between silicon and borosilicate glass are investigated for compatibility with a diode laser crystallization technique for fabrication of thin-film polycrystalline silicon solar cells. SiCx, SiN x and SiOx layers or multilayer stacks of these materials have allowed silicon films of 10μm thickness to be successfully crystallized by diode laser irradiation without dewetting, with each option offering different advantages. SiCx allows the most robust crystallization process, while SiOx is the best barrier to contamination and the most stable layer. SiNx offers the best anti-reflection coating for superstrate configured solar cells. Presently, best device performance is achieved with a SiOx intermediate layer with cells achieving up to ∼540 mV open-circuit voltage. © 2012 Materials Research Society.

Eggleston B.,University of New South Wales | Eggleston B.,Suntech R and D Australia Pty. Ltd. | Varlamov S.,University of New South Wales | Huang J.,University of New South Wales | And 4 more authors.
Materials Research Society Symposium Proceedings | Year: 2012

A new method to form high quality crystalline silicon thin films on cheap glass substrates is developed using a single pass of a line-focus cw diode laser in air. The laser process results in the formation of large high-quality crystals as they grow laterally in the scan direction - seeded by the previously crystallised region. Grains 10 pm in thickness, up to millimetres in length and hundreds of microns in width have been grown with virtually zero detectable intragrain defects. Another mode is found which results in much smaller crystals grown by partial melting. The dominant grain boundaries identified are Σ3 <111> 60° twins. Hall mobilities as high as 470 cm2/Vs have been recorded. A diffused emitter is used to create a p-n junction at the rear of the films which produces open-circuit voltages as high as 539 mV. © 2012 Materials Research Society.

Young T.L.,Suntech RandD Australia Pty Ltd | Hee K.,Suntech RandD Australia Pty Ltd | Lennon A.J.,University of New South Wales | Egan R.J.,Suntech RandD Australia Pty Ltd | And 2 more authors.
2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014 | Year: 2014

Strong contact adhesion is an important requirement for durable, manufacturable solar cells. Advanced contacting technologies require new methods to measure adhesion. We describe a scratch test for measuring contact adhesion that involves scanning a weighted stylus across the cell while measuring the horizontal force FD required to dislodge the contacts. FD is characteristic of the adhesive bond but independent of the contact height, stylus weight and scan speed. We observe that contact peeling depends also on the tensile strength of the metal finger. The tests provide a valuable way to assess and optimize the adhesion of metal contacts. © 2014 IEEE.

Eggleston B.,Suntech RandD Australia Pty Ltd | Eggleston B.,University of New South Wales | Varlamov S.,University of New South Wales | Green M.,University of New South Wales
IEEE Transactions on Electron Devices | Year: 2012

A new process was presented to anneal crystallographic defects in solid-phase crystallized silicon that produces higher Suns-V oc voltages than the conventional belt-furnace annealing (BFA) process. A few-millisecond continuous-wave diode laser treatment anneals defects present in the polycrystalline silicon and activates dopants. It is shown that the silicon/glass-interface system reaches an effective steady state at every point during the laser treatment, and the relative temperature profile is determined by the laser beam profile rather than its power or scanning speed. The peak temperature that is reached during a few-millisecond laser exposure is shown to increase and then level off with laser dose, indicating partial recrystallization of the film. A reduction in boron-doped p-type sheet resistance and phosphorus-doped emitter resistance is reported for a wide range of laser dose and scanning speed. The highest substrate temperature required during the process sequence is reduced from 960 °C to 620 °C. A peak 1-sun voltage of 492 mV is achieved using a 4-ms exposure at 500-J · cm -2 laser dose, which is an improvement of 32 mV over the voltage after optimized BFA. © 2012 IEEE.

Dore J.,University of New South Wales | Dore J.,Suntech RandD Australia Pty Ltd | Varlamov S.,University of New South Wales | Green M.A.,University of New South Wales
IEEE Journal of Photovoltaics | Year: 2015

The intermediate layer (IL) between the glass and silicon plays an important role in laser-crystallized thin-film silicon solar cells. {\rm SiO}-x, {\rm SiN}-x, and {\rm SiC}-x deposited by RF sputtering or plasma-enhanced chemical vapor deposition, either as single layers or in stacks, have been tested as ILs with regard to silicon wettability and silicon crystal quality and the effect of hydrogen passivation. {\rm SiC}-x is the best wetting layer, allowing a larger laser crystallization process window than {\rm SiO}-x or {\rm SiN}-x. {\rm SiN}-x layers are limited by pinholing, which increases in severity with laser fluence. {\rm SiO}-x ILs result in lower silicon grain-boundary density compared with {\rm SiC}-x-based layers and to {\rm SiN}-x-based layers. Hydrogen passivation of laser-crystallized silicon on single layer {\rm SiO}-x has no impact on V-{{\rm OC}} , while an improvement of around 60 mV is found for samples on {\rm SiO}-x/{\rm SiN}-x/{\rm SiO}-x stacks. Diffusion of dopants from the IL are found to create a uniformly doped absorber with no evidence of a front-surface field. © 2011-2012 IEEE.

Dore J.,University of New South Wales | Dore J.,Suntech RandD Australia Pty Ltd | Evans R.,Suntech RandD Australia Pty Ltd | Schubert U.,Suntech RandD Australia Pty Ltd | And 11 more authors.
Progress in Photovoltaics: Research and Applications | Year: 2013

Polycrystalline silicon films of 10 μm thickness are formed on glass in a single-step continuous wave diode laser crystallisation process, creating large crystal grains up to 1 mm wide and 10 mm long. Solar cells are formed on the layers by employing a rear point contacting scheme. Intermediate layers between the glass and the silicon are shown to heavily influence the cell characteristics. A stack of silicon oxide/silicon nitride/silicon oxide has produced the best cell efficiency so far of 8.4 % with open-circuit voltage of 557 mV. With simple optimisation of the contacting scheme, 10 % efficient cells are expected in the near future. Copyright © 2012 John Wiley & Sons, Ltd.

Dore J.,University of New South Wales | Dore J.,Suntech RandD Australia Pty Ltd | Ong D.,Suntech RandD Australia Pty Ltd | Varlamov S.,University of New South Wales | And 2 more authors.
IEEE Journal of Photovoltaics | Year: 2014

Diode laser crystallization of thin silicon films on the glass has been used to form polycrystalline silicon layers for solar cells. Properties of an intermediate layer stack of sputtered SiOx/SiNx/SiO x between the glass and the silicon have been improved by reactively sputtering the SiNx layer, which result in enhanced optical and electrical performance. Light trapping is further enhanced by texturing the rear surface of the silicon prior to metallization. An initial efficiency of 11.7% with VOC of 585 mV has been achieved using this technique, which are the highest values reported for poly-Si solar cells on glass substrates. Cells suffer a short term, recoverable degradation of VOC, and fill factor. The magnitude of the degradation is reduced via the repeated thermal treatment. A selective p+ metallization scheme has been developed which eliminates the degradation altogether. © 2011-2012 IEEE.

Steffens S.,Helmholtz Center Berlin | Becker C.,Helmholtz Center Berlin | Zollondz J.-H.,CSG Solar AG | Chowdhury A.,LInstitut dElectronique du Solide et des Systemes | And 5 more authors.
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2013

A variety of defect healing methods was analyzed for optimization of polycrystalline silicon (poly-Si) thin-film solar cells on glass. The films were fabricated by solid phase crystallization of amorphous silicon deposited either by plasma enhanced chemical vapor deposition (PECVD) or by electron-beam evaporation (EBE). Three different rapid thermal processing (RTP) set-ups were compared: A conventional rapid thermal annealing oven, a dual wavelength laser annealing system and a movable two sided halogen lamp oven. The two latter processes utilize focused energy input for reducing the thermal load introduced into the glass substrates and thus lead to less deformation and impurity diffusion. Analysis of the structural and electrical properties of the poly-Si thin films was performed by Suns-VOC measurements and Raman spectroscopy. 1 cm2 cells were prepared for a selection of samples and characterized by I-V-measurements. The poly-Si material quality could be extremely enhanced, resulting in increase of the open circuit voltages from about 100 mV (EBE) and 170 mV (PECVD) in the untreated case up to 480 mV after processing. © 2012 Elsevier B.V. All rights reserved.

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