High rate growth of microcrystalline silicon at low temperatures

Resolving the nanostructure of plasma-enhanced chemical vapor deposited nanocrystalline SiOx layers for application in solar cells

“…The total pressure is critical for optimizing the deposition process, because it influences the power density per molecule (thus dissociation), the particle residence time, which affects the gas depletion; and the potential difference between the plasma bulk and sheath and therewith, the extent of ion bombardment. The reduction in a crystalline silicon volume fraction with higher deposition pressure observed in the samples studied here can be explained by either the higher silane depletion, which suppresses the atomic hydrogen annihilation reaction in the gas phase, 29 or reduced ion bombardment. 22 While the refractive index is mainly determined by the [O]/[Si] ratio, 2 the conductivity depends on the nanostructure and the crystallinity.…”

Microcrystalline silicon solar cells deposited at high rates

“…As a possible solution for high-growth conditions of c-Si:H without damage to the surface layer, the highpressure depletion method was proposed. 3,11 In this approach, the application of a high discharge power is used to decompose most of the silane in initial reactions of the type SiH 4 → SiH x + ͑4−x͒H. Under the silane-depletion condition, the reaction…”

“…A way to reduce ion energies in PECVD systems is the use of a third electrode in a triode arrangement. 1,3,4 With an independent bias on this electrode with respect to the grounded substrate, ion energies can be controllably reduced. Other effective methods to reduce ion energies while maintaining high deposition rates are ͑i͒ very high frequency ͑VHF͒ excitation of the discharge, where lower peak-to-peak voltages for a given discharge power result in lower maximum-ion energies, [5][6][7][8][9] and ͑ii͒ high working pressure ͑p depo ͒ with an increased discharge power, where ion energies are reduced by multiple collisions in the plasma sheath.…”

“…[10][11][12] Recently, also combinations of VHF-PECVD and high working pressure have been investigated. 3,[13][14][15][16][17] In the present paper we report on further studies of such a combination of VHF-PECVD at 94.7 MHz at high working pressures of 2-4 hPa for the growth of c-Si:H at high deposition rates. As high pressure is combined with high discharge power, we shall refer to this deposition regime as high pressure-high power ͑hphP͒ in contrast to the low powerlow pressure ͑lplP͒ conditions in conventional RF-and VHF-PECVD.…”

At the limit of total silane gas utilization for preparation of high-quality microcrystalline silicon solar cells at high-rate plasma deposition

“…Several studies point out that high discharge powers P, high deposition pressures p, a showerhead ͑SH͒ type of gas inlet through the powered electrode, and a small electrode distance are favorable for the high-rate deposition of high-quality c-Si. 3,7,[10][11][12] In the present letter, the influences and the interdependencies of these individual processes and configuration parameters on the performance, deposition rate, and silane gas utilization rate of c-Si: H solar cells ͑defined as the fraction of the silicon atoms entering the plasma as SiH 4 that contributes to the layer growth͒ are studied separately. Hereto, at each condition a series of complete solar cells with different source gas SC was made, leading to a variation in crystalline volume fraction in c-Si: H. Thus, the point of "optimal phase mixture" can be identified for each series as the point leading to optimal solar cell performance.…”