Experimental verification of the effect of depletion-region modulation on photoconductance lifetime measurements

Abstract

Depletion-region modulation (DRM) has recently been identified as a mechanism that influences photoconductance lifetime measurements. The effect is observed in semiconductor samples containing a depletion-region (i.e., $\mathrm{p-n}$ junction solar cells). Experimental measurements presented within demonstrate that the DRM effect dominates the conductance measurement at low excess carrier concentrations, resulting in an overestimation of the effective lifetime by several orders of magnitude. The influence of substrate thickness on the DRM effect is experimentally verified. The previously developed analytical equation for DRM is in agreement with our experimental data and can be used to correct DRM affected photoconductance lifetime measurements. Finally, the impact on the sensitivity of a photoconductance measurement is discussed for the DRM corrected case.