A Contactless Method for Determining the Carrier Mobility Sum in Silicon Wafers

Abstract

Abstract-In this paper, we present a new method to determine the simultaneous injection and temperature dependence of the sum of the majority and minority carrier mobilities in silicon wafers. The technique is based on combining transient and quasi-steadystate photoconductance measurements. It does not require a full device structure or contacting but only adequate surface passivation. The mobility dependence on both carrier injection level and temperature, as measured on several test samples, is discussed and compared with well-known mobility models. The potential of this method to measure the impact of dopant concentration, compensation ratio, injection level, and temperature on the mobility is demonstrated.

Measurement and Parameterization of Carrier Mobility Sum in Silicon as a Function of Doping, Temperature and Injection Level

“…The mobility sum is determined by comparing transient photoconductance decay and quasi-steady state photoconductance (QSSPC) measurements of the excess conductance (Δσ) for every sample. More details of the method can be found in [13]. To obtain accurate measurements using this technique, sufficient low surface recombination velocity (SRV) is required to ensure a uniform excess carrier profile.…”

“…In this section, the empirical expression is compared with mobility sum data at 300 K previously measured by the photoconductance technique on p-type boron doped 0.9 Ω.cm and 100-1000-Ω.cm silicon [13]. Fig.…”

Impact of compensation on the boron and oxygen-related degradation of upgraded metallurgical-grade silicon solar cells

“…This fit is accurate in uncompensated Si [23] but overestimates the mobility sum in compensated Si [ref Ziv]. To account for that lower mobility in our samples, we adjust the doping used as input in the fit to…”

Contactless determination of the carrier mobility sum in silicon wafers using combined photoluminescence and photoconductance measurements

“…Some information can be found in the literature; 3,4 however, so far, this data has been mainly obtained from high-resistivity Si wafers. The few measurements on low-resistivity substrates 15,16 were limited to a relatively narrow injection range. Hence, there is a need for an injectiondependent mobility measurement technique to allow development of new injection-dependent mobility models that can be used for device characterization and simulation.…”