Quantitative self-calibrating lock-in carrierographic lifetime imaging of silicon wafers

Abstract

Quantitative self-calibrating lock-in carrierography (LIC) imaging of crystalline silicon wafers is introduced using an InGaAs camera and a spread super-bandgap illumination laser beam. Images at several modulation frequencies and a simplified model based on photocarrier radiometric theory are used to construct the effective carrier lifetime image from the phase-frequency dependence. The phase image data at several frequencies and at selected locations on a wafer were compared to frequency scans obtained with a single-element InGaAs detector, and good agreement was found. The quantitative LIC lifetime imaging capability demonstrated in this work is self-calibrating and eliminates the requirement for calibration in conventional photoluminescence imaging.