Space charge limited current effects in silicon at high injection levels

Published

June 20, 2010

Author(s)

Ari D. Feldman, Richard K. Ahrenkiel

Abstract

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

Pub Type

Conferences

Keywords

photovoltaic, silicon, solar cell, space charge limited current

Citation

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 March 14, 2025)