DETERMINATION OF CARRIER MOBILITY SUM IN SILICON WAFERS BY COMBINED PHOTOLUMINESCENCE AND PHOTOCONDUCTANCE MEASUREMENTS

摘要

The charge carrier mobility is a key material parameter for photovoltaic applications. The dependences of the mobility on bulk dopant density, on injection level and on temperature are well known in the case of noncompensated crystalline silicon. Still, it remains unclear in the case of dopant compensation. A wide variety of methods, such as combined infrared radiation and voltage measurements or combination of quasi-steady-state photoconductance and quasi-steady-state open-circuit voltage measurements were employed in the past to measure the mobility. However, most of these methods require contacts and a relatively complicated structure of the sample. Recently, a new contactless method to determine the carrier mobility sum, based on a comparison between quasisteady- state photoconductance and transient photoconductance decay measurements was proposed. However, it seems that this method is currently limited to injection levels in the 1×10~(15) to 1×10~(16) cm~(-3) range. In this paper we present a novel method to determine the mobility sum, based on combined photoconductance and photoluminescence measurements. A mobility sum in the injection level range 1×10~(13) to 1×10~(17) cm~(-3) can be determined using the proposed method.