The electroluminescence intensity from Si cells under the forward bias was found to have one to one quantitative agreement with the minority carrier diffusion length. Based on the diffusion equation and simple p-n diode model, the electroluminescence intensity was analyzed relative to the cell performance. Electroluminescence intensity is proportional to the product of the injected minority carrier density and the effective diffusion length. The diode ideality factor n can be deduced by measuring the electroluminescence intensity as a function of the forward injection current. Among various crystalline silicon cells including single and polycrystalline types, the measured electroluminescence intensity at a fixed forward current has a tight relationship with the open circuit voltage of each cell, which gives a very convenient way to evaluate cell performance.

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Selective emitter formation for crystalline silicon (c-Si) solar cells is very important to increase conversion efficiency. Laser doping (LD) is a very simple method for selective emitter formation because the use of masks and photolithography is unnecessary. In this paper, we report an application of LD to form a selective emitter in n-type c-Si solar cells. Our results demonstrated that the doping profile of the selective emitter showed a high doping concentration and deep doping depth. The conversion efficiency of solar cells with selective emitter formed by LD was increased. In particular, the short-circuit current density was considerably increased.

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The effect of passivation layers (SiOX, SiNX, etc.) using plasma-enhanced chemical vapor deposition (PECVD) for crystalline silicon solar cells showed high surface recombination with decreasing of deposition temperature (<300 °C). The surface of Czochralski (Cz) monocrystalline silicon (c-Si) wafer was exposed to an NH3 plasma before the low-temperature deposition of silicon nitride (SiNX) layer or amorphous silicon (a-Si:H) layer in a system respectively. The effect of NH3 plasma treatment for the interface was observed by microwave photoconductance decay (µ-PCD), quasi-steady-state photoconductance (QSSPC), Fourier transform infrared spectroscopy (FT-IR), secondary ion-microprobe mass spectrometry (SIMS), and X-ray photoemission spectroscopy (XPS). The effective lifetime (τeff) with NH3 plasma treatment exceeded τeff without the treatment. Even in the case of very low deposition temperature (100 °C), τeff is improved dramatically (about 38 times). This NH3 plasma treatment effect was caused by hydrogenation and carbon cleaning from the SIMS measurement. It was found that SiNX films with excellent surface passivation properties can be deposited at 100 °C.