Contactless Technique for Measuring Minority-Carrier Parameters in Silicon
Characterization of minority-carrier parameters is a primary interest for a range of devices, including solar cells. For 'on-line' testing needs, contactless techniques are mandatory, as any diagnostic requiring contact formation is impractical. Here, we will describe the resonance-coupled photoconductive decay (RCPCD) technique that has proven to be a valuable diagnostic for a number of semiconductor technologies. This technique avoids some of the inherent limitations of microwave reflection. Our system is a pump-probe technique, using an optical pump and a microwave probe (400 to 900 MHz). These low frequency microwaves penetrate most silicon wafers with common doping levels. By varying the optical excitation wavelength, one can probe wafers of standard (300 to 400 {micro}m) wafer thickness. Also, the method is very linear in sample photoconductivity, and we have observed a linear response over more than three orders of magnitude of excess carrier concentration. This attribute allows us to measure the carrier recombination lifetime over many decades of injection level, allowing the use of a procedure that is called injection-level spectroscopy (ILS). The RCPCD technique was developed [1,2,3,4,5,6] at the National Renewable Energy Laboratory (NREL) and has been applied to more than 5000 samples, ranging from small-area thin films to 350-{micro}m-thick, 250-mm-diameter silicon wafers. In addition, the lifetimes in semiconductor ingots of irregular shape have been successfully measured as no particular size or shape is required for the RCPCD analysis.
- Research Organization:
- National Renewable Energy Lab., Golden, CO. (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC36-99-GO10337
- OSTI ID:
- 15006759
- Report Number(s):
- NREL/CP-520-35649; TRN: US200411%%303
- Journal Information:
- 12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Extended Abstracts and Papers from the workshop held 11-14 August 2002, Breckenridge, Colorado, Conference: 12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Extended Abstracts and Papers from the workshop, Breckenridge, CO (US), 08/11/2002--08/14/2002; Other Information: PBD: 1 Aug 2002
- Publisher:
- Golden, CO: National Renewable Energy Laboratory
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
DECAY
EXCITATION
LIFETIME
NATIONAL RENEWABLE ENERGY LABORATORY
PHOTOCONDUCTIVITY
PROBES
RECOMBINATION
REFLECTION
SHAPE
SILICON
SOLAR CELLS
SPECTROSCOPY
TESTING
THICKNESS
THIN FILMS
PV
CRYSTALLINE SILICON
SOLAR CELL MATERIALS
12TH WORKSHOP
SOLAR ENERGY - PHOTOVOLTAICS