Microcrystalline silicon solar cells with an open-circuit voltage above 600mV

Abstract

Microcrystalline silicon solar cells with an open-circuit voltage surpassing the 600mV barrier were prepared by combining the use of a hot wire deposited p-i interface with that of an i layer deposited by radio-frequency parallel plate plasma deposition using controlled SiH4 flow profiling. The control of the bulk and interface properties facilitated effective charge carrier collection from i layers with a crystalline volume fraction as low as ∼30%. Judging from the absorption in the infrared and the excellent charge carrier transport, the optoelectronic properties of this material were still dominated by the crystalline rather than the amorphous phase.

High-rate deposition of microcrystalline silicon p-i-n solar cells in the high pressure depletion regime

“…Figures 9͑b͒-9͑d͒ show the typical narrow range of shapes of the hydride SM spectra, at which solar cells with reasonable material properties can be expected ͑V oc Ͼ 480 mV͒. The best cell performance obtained for depositions using silane profiling ͑series E and F͒ is V oc = 497 mV, J sc = 20.6 mA cm −2 , FF= 0.68, and = 7.0 ͑see Table II͒. If we consider the highest V oc values for c-Si: H p-i-n devices which are deposited at low deposition rates ͑540-600 mV͒, 66 the value of V oc = 497 mV is still rather low. This implies that in contrast to condition D, the initial growth is not too amorphous but too crystalline for series F. An additional profiling step of the employed power density was introduced step ͑deposition series G͒, to move the deposition conditions during the first 40 s after plasma ignition even closer to the a → c transition, while preserving the optimum shape of the SM spectra in the IR.…”

Probing the phase composition of silicon films in situ by etch product detection

“…Optical emission spectroscopy ͑OES͒ is an easy-to-implement in situ diagnostic which is applied frequently to monitor process drifts and to relate the relative abundance of emissive species in the deposition process to resulting film properties. [5][6][7][8][9][10] Due to the importance of the atomic hydrogen to SiH x radical flux ratio, emission intensity ratios between excited H * and SiH * ͑or Si * ͒ emission have been correlated to the film crystallinity. [7][8][9][10] Nonetheless, such ratios are strictly empirical, reactor dependent, and require ex situ calibration.…”

Low concentrator hetero-junction microcrystalline silicon solar cells

“…From our theoretical analysis [5], we observe that the V oc increases with wide-gap p-layer because the potential barrier at p/i interface increases and effectively suppresses the electron back-diffusion from i-layer to p-layer [14]. The suppression of the back diffusion results in the low recombination in the p-layer and at the p/i interface under low-light concentration.…”

“…The optimization of single-junction μc-Si:H solar cells is needed to obtain tandem cells with higher efficiency. In the optimization of singlejunction μc-Si:H solar cell, research on the p/i interface is important since the p/i interface has a significant impact on the solar cell performance when the i-layer quality is very good [1][2][3][4][5]. In our previous work [6], we have investigated the effect of p-layer band gap on the performance of μc-Si:H p-i-n type single-junction solar cells by theoretical analysis.…”