Abstract: A time-resolved photoluminescence technique is disclosed to image photovoltaic cells and wafers. The effective lifetime is measured directly using a photodetector that has a fast response. A pulsed light source flashes the wafer, generating excess carriers in the silicon. The rate of carrier recombination is monitored by imaging the photoluminescence decay over time. An effective lifetime can be extracted from the photoluminescence decay curve, which can be used to determine the quality of the photovoltaic cells and wafers.

Abstract: A portable Raman spectroscopy instrument capable of discriminating between chemicals in the solid, liquid and vapor states is described. The instrument is in the shape of a gun and uses a solid state detector and an NIR laser. It relies on gating techniques to minimize weight and lower energy needs.