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Space charge limited current effects in silicon at high injection levels



Ari D. Feldman, Richard K. Ahrenkiel


The space charge limited current (SCLC) effect will be analyzed in undoped crystalline silicon wafers at high injection levels. Space charge limited currents develop when the electric field from the injected carriers exceeds that of the background doping. This becomes a relevant phenomenon when applied to materials that use undoped wafers such as back-contact solar cells. It may also be applicable to silicon and non-silicon concentrator cells. The SCLC effect may be significant in the epitaxial thin film materials used in space photovoltaics. Our study uses Resonant Coupled Photoconductive Decay (RCPCD) to analyze and estimate the SCLC effect via photoconductive carrier lifetime measurements. An undoped Si sample was subjected to the high injection of excess carries by using a pulsed laser source. The excess carrier densities were well above background doping, creating an excess carrier density of approximately 3 x 1017 cm-3. This is well above the background carrier density of 1.73 x 1013 cm-3 (measured by Capacitance-Voltage techniques). The SCLC effect is detected by observing irregularities, such as positive slope of the photoconductive decay curve in the initial, very high injection portion of the process. A theory of the SCLC effect will be developed and data will be presented.
Proceedings Title
Proceeding of the 2010 IEEE Photovoltaic Specialists Conference
Conference Dates
June 19-26, 2010
Conference Location
Honolulu, HI
Conference Title
2010 IEEE Photovoltaic Specialists Conference


photovoltaic, silicon, solar cell, space charge limited current


Feldman, A. and Ahrenkiel, R. (2010), Space charge limited current effects in silicon at high injection levels, Proceeding of the 2010 IEEE Photovoltaic Specialists Conference, Honolulu, HI (Accessed June 15, 2024)


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Created June 19, 2010, Updated November 2, 2020