Использование двигателя-маховика для создания управляющих моментов космического аппарата

In this article we present a comprehensive study of microcrystalline silicon (PC-Si:H) p-i-n solar cells prepared by using plasma-enhanced chemical vapor deposition (PECVD) at 13.56 MHz excitation frequency. In the first step the cell development was performed in a small area PECVD reactor showing the relationship between the deposition process parameters and the resulting solar cell performance. Subsequent up-scaling to a substrate area of 30 X 30 cm confirmed the scalability of optimized deposition parameters to large area reactors. We investigated the deposition regime of high rf power P (rf) (0.25-0.7 W/cm(2)) and high deposition pressure P (dep) (1 - 11 Torr) for the muc-Si:H i layer. Furthermore, the influence of silane concentration and deposition temperature was studied. A transition between amorphous and microcrystalline growth could be achieved by a variation of either deposition pressure, plasma power, or silane concentration. The best microcrystalline silicon solar cells were prepared close to the transition to amorphous growth. A high deposition pressure was a prerequisite for obtaining, high quality material at a high growth rate. The best solar cell efficiencies achieved so far are 8.1% and 6.6% at i-layer growth rates of 5 and 10 Angstrom/s, respectively, for muc-Si:H single junction cells. Applied in a-Si:H/muc-Si:H tandem cells a stabilized efficiency of 10.0% was achieved. (C) 2002 American Vacuum Society

Microcrystalline silicon solar cells prepared by 13.56 MHz PECVD-prerequisites for high quality material at high growth rates

Topic of this thesis was the development of thin film solar cells based on microcrystalline silicon prepared by 13.56 MHz PECVD (plasma-enhanced chemical vapor deposition) at high deposition rates. Comprehensive solar cell studies, which were accompanied by material studies, resulted in the identification of the most important prerequisites for high quality solar cells at high growth rates. During the development of solar cells in various pressure regimes, a high deposition pressure emerged as key parameter for good solar cell performance at high deposition rates. Plasma ignition at high deposition pressures (>10 Torr) was only possible at low electrode distances. Other important factors were a high total gas flow and a substrate temperature, which should not exceed $\sim$200 °C. As alternative approach deposition by pulsed plasma excitation was investigated. At deposition rates up to $\sim$5 $\mathring{A}$/s efficiencies comparable to continuous excitation were achieved, at higher rates the efficiency significantly decreased. In summary we succeeded in developing high quality solar cells at high deposition rates. Highlights were solar cells with 9.1, 9.0 and 8.9 % efficiency for deposition rates of 1, 3 and 4 $\mathring{A}$/s, respectively. At 9 $\mathring{A}$/s still a high efficiency of 7.9 % was achieved. Furthermore we gained an understanding of the prerequisites regarding the plasma properties to achieve high growth rates and high quality material

Microcrystalline silicon solar cells prepared by 13.56 MHz PECVD Prerequisites for high quality material at high growth rates

Topic of this thesis was the development of thin film solar cells based on microcrystalline silicon prepared by 13.56 MHz PECVD (plasma-enhanced chemical vapor deposition) at high deposition rates. Comprehensive solar cell studies, which were accompanied by material studies, resulted in the identification of the most important prerequisites for high quality solar cells at high growth rates. During the development of solar cells in various pressure regimes, a high deposition pressure emerged as key parameter for good solar cell performance at high deposition rates. Plasma ignition at high deposition pressures (>10 Torr) was only possible at low electrode distances. Other important factors were a high total gas flow and a substrate temperature, which should not exceed #propor to#200 C. As alternative approach deposition by pulsed plasma excitation was investigated. At deposition rates up to #propor to#5 A/s efficiencies comparable to continuous excitation were achieved, at higher rates the efficiency significantly decreased. In summary we succeeded in developing high quality solar cells at high deposition rates. Highlights were solar cells with 9.1, 9.0 and 8.9% efficiency for deposition rates of 1, 3 and 4 A/s, respectively. At 9 A/s still a high efficiency of 7.9% was achieved. Furthermore we gained an understanding of the prerequisites regarding the plasma properties to achieve high growth rates and high quality material. (orig.)SIGLEAvailable from TIB Hannover: RA 831(4083) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman