Title:	Photoluminescence Imaging of as-Cut Wafers Combined with Lifetime Calibration by MW-PCD Technique
Author(s):	F. Korsós, J. Csontos, Z. Kiss, G. Nádudvari, P. Tüttö, Z. Tóth, M. Wilson
Keywords:	Photoluminescence, Carrier Lifetime, Saw Damage
Topic:	Wafer-Based Silicon Solar Cells and Materials Technology
Subtopic:	Silicon Feedstock, Crystallisation and Wafering
Event:	27th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2AV.4.55
Pages:	1068 - 1071
ISBN:	3-936338-28-0
Paper DOI:	10.4229/27thEUPVSEC2012-2AV.4.55
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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We present a new realization of in-line photoluminescence imaging combined with conventional microwave photo-conductance decay (MW-PCD) measurements. Simultaneous MW-PCD lifetime measurement can serve as in-situ calibration for photoluminescence imaging measurement converting the PL image captured by a CCD or CMOS camera into a high resolution carrier lifetime map. In the present work the application of PLI method for inspection of as-cut multicrystalline silicon wafers is in focus. Variation in surface conditions of the as-cut wafers (especially saw damage region properties) can cause an uncontrolled PL signal level which depends on the actual properties of the damaged region and not the electrical quality of the bulk. Etching the top layer off may increase PL signal by a factor of 2-3. We show that although the damage region impacts the amplitude of MW-PCD transients, the evaluated lifetime from the decay curves is independent of the properties of the surface damaged region. Thus, using the lifetime values measured by MW-PCD on the actual as-cut wafers as a reference for calibration of PL images, the resulted PLI lifetime maps are independent of the surface damage layer.