Efficient production technology for microcrystalline silicon solar cells using a Localized Plasma Confinement (LPC) CVD method

Abstract

A very high deposition rate for high-quality microcrystalline silicon (lJc-Si) films has been achieved under very high-pressure conditions (> 1,000 Pa) using a Localized Plasma Confinement (LPC)-CVD method which has a special cathode.The uniformity of the IJc-Si film thickness was 2.4% on a 55x65 cm 2 glass substrate with a deposition rate of 2.7 nm/s. We also achieved maximum conversion efficiency of 11.4% for an a-Si/lJc-Si tandem solar cell (1 cm 2 ) on a 20x20 cm 2 glass substrate and average conversion efficiency of 9.84% for a-Si/lJc-Si tandem solar cells (1 cm 2 ) on a 55x65 cm 2 glass substrate with a deposition rate (Rd) of 1.8 nm/s. These results indicate that LPC-CVD method is a good candidate as an effective production technology for large-area, high-performance IJc-Si thin-film solar cells.

High‐rate deposition of microcrystalline silicon in a large‐area PECVD reactor and integration in tandem solar cells

“…To the best of our knowledge, our stabilized efficiency of h ¼ 9.6% is among the highest conversion efficiencies achieved for tandem solar cells with a bottom cell deposited at high-rate (1 nm/s) in a large-area parallel plate PECVD capacitive reactor, without the use of a modified cathode, such as multi-hollow [22] and laddershaped cathodes [23].…”

“…Using a larger reactor (138 Â 74 cm 2 substrate carrier area), they also reported an average initial aperture area efficiency higher than 10% for tandem mini-modules (10 Â 10 cm 2 and 30 Â 30 cm 2 ) deposited at 5 Å /s, using RF [21]. Sanyo achieved an average efficiency of 9.8% at 15 Å /s (1 cm 2 cells, maximum h ¼ 10.5%) on a 55 Â 65 cm 2 substrate, using a multi-hollow cathode [22]. Mitsubishi Heavy Industries reported an 11% initial efficiency on a mini-module of 40 Â 50 cm 2 and ongoing studies for high deposition rates on 1.4 Â 1.1 m 2 area, using a ladder shaped electrode [23].…”

Review of thin-film silicon deposition techniques for high-efficiency solar cells developed at Panasonic/Sanyo

“…To achieve large-area and high-rate deposition of μc-Si film by generating stable and uniform SiH 4 plasma in the high-pressure range of over 1000 Pa, we have been developing a unique process that we term "localized plasma confinement (LPC) CVD" [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. Fig.…”

“…The μc-Si produced by this method has been confirmed to show a good crystalline structure and crystal orientation suited for use in solar cells. For a substrate size of 550 mm  650 mm (equivalent to the FPD industry's 3.5th generation), a film deposition-rate of 2.7 nm/s and film thickness distribution of 72.4% has been obtained, indicating good uniformity in the plane [10,23]. Development of a-Si/μc-Si tandem solar cells with μc-Si produced by LPC-CVD and adopted for the bottom cell are in progress in parallel.…”

Influence of pressure and silane depletion on microcrystalline silicon material quality and solar cell performance

“…[3][4][5] Presently, these seem to be among the main concerns for lowering industrial manufacturing costs. A wide range of parameters influences the deposition conditions and hence the material quality of c-Si: H. First, hardware parameters: electrode geometry, [6][7][8] interelectrode distance, [9][10][11] and operating frequency. [12][13][14] Second, process parameters, easily adjustable for a given reactor: power density, pressure, substrate temperature, and input gas flows.…”