Extraordinarily High Minority Charge Carrier Lifetime Observed in Crystalline Silicon

Abstract The influence of a p-type Si with different resistivity, charge carrier lifetime and emitter dopant impurities concentration on the crystalline silicon solar cells parameters were analyzed and experimentally checked. The findings were determined by quasi-steady-state photoconductance, current-voltage and spectral response methods. The study was accompanied by solar device simulation using a numerical PC1D program. The highest photoconversion efficiency of 15.13 % was obtained for the moncrystalline (Cz-Si) solar cell with a base resistivity of 1.8 Ωcm and an effective charge carrier lifetime of 22.9 μs. The results clearly confirmed the importance concerning the dopant level in a Si base material in relation to open circuit voltage and short circuit current possible to obtain from the solar cell. Reduction of a base material resistivtiy leads to a lower value of an effective charge carrier lifetime and photoconversion efficiency both for Cz-Si and multicrystalline (mc-Si) solar cells. The experimental results and calculation showed, that in the case of a solar cell produced on the basis of crystalline silicon, the most important spectral range for an efficiency of a cell is covering a wavelength range of 587 ÷ 838 nm.

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Nonequilibrium Charge Carrier Lifetime Testing Equipment for Semiconductor Materials by a Contactless Microwave Phase Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.655-657.830 ◽

2013 ◽

Vol 655-657 ◽

pp. 830-833

Author(s):

Song Chen ◽

Zu Rong Ni ◽

Fen Xiao

Keyword(s):

Charge Carrier ◽

Carrier Lifetime ◽

Crystalline Silicon ◽

Nonequilibrium Charge Carrier ◽

Testing Equipment ◽

Phase Method ◽

Automatic Data ◽

Crystalline Silicon Solar Cells ◽

Lock In ◽

Charge Carrier Lifetime

The accurate measurement of nonequilibrium charge carrier lifetime is of vital significance in research and manufacture of crystalline silicon solar cells. A testing equipment based on a contactless microwave phase method was implemented by being embedded with GPIB, FPGA and a lock-in analyzer. A friendly operation interface was developed, based on the graphic programming language LabVIEW. The virtue of the equipment is achieved by automatic data acquisition and processing, which improves the automatization, efficiency and accuracy of the measurement.

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Investigation of Defects in the Edge Region of Multicrystalline Solar Silicon Ingots

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.108-109.531 ◽

2005 ◽

Vol 108-109 ◽

pp. 531-538 ◽

Cited By ~ 8

Author(s):

M. Rossberg ◽

M. Naumann ◽

K. Irmscher ◽

U. Juda ◽

A. Lüdge ◽

...

Keyword(s):

Charge Carrier ◽

Phase Boundary ◽

Carrier Lifetime ◽

Interstitial Oxygen ◽

Minority Charge Carrier ◽

Convex Shape ◽

Laser Scattering ◽

Photoconductivity Decay ◽

Solar Silicon ◽

Charge Carrier Lifetime

The structural and electrical properties of as grown multicrystalline (mc) solar silicon have been characterized with special emphasis on the ingot's edge regions. For this purpose a vertical cross section of an mc-Si Bridgman ingot was investigated by Fourier transform infrared spectroscopy (FTIR), laser scattering tomography (LST), lateral photovoltage scanning (LPS), infrared microscopy and microwave detected photoconductivity decay (&PCD). Images of the distribution of dislocations, grain boundaries, precipitates, impurities (O, N, C) and the minority charge carrier lifetime were obtained, partly differentiating the defects by their electrical activity. In particular the LPS method displays dopant striations indicating the shape of the phase boundary. Deviations of the phase boundary from a slightly convex shape in the middle of the ingot to a concave one in the vicinity of the side walls could be observed. The existence of an horizontal temperature gradient deduced from this shape is the reason for convection in the melt. The influence on the concentration profiles of interstitial oxygen and the correlation with the minority charge carrier lifetime are discussed.

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