Decoupling bulk- and surface-limited lifetimes in thin kerfless silicon wafers using spectrally resolved transient absorption pump-probe spectroscopy and computer simulations

Abstract

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2013.Cataloged from PDF version of thesis.Includes bibliographical references (p. 84-86).One of the key technological objectives to further decrease the cost of silicon (Si) PV and enable manufacturing of crystalline silicon is to improve the quality of thin, kerfless Si wafers to monocrystalline equivalent. To aid wafer manufacturers to develop high-quality thin Si wafer substrates, performance-limiting defects in the bulk of thin kerfless Si wafers must be identified, and a means to accurately measure the bulk lifetime is necessary. With decreasing wafer thickness, however, the impact of surface recombination increases and dominates the effective lifetime measured by conventional methods. Therefore, the ability to decouple bulk-limited lifetime from surface-limited lifetime is desirable, ideally without the need for surface passivation. Herein, spectrally resolved transient absorption pump-probe spectroscopy and extensive Technology Computer Aided Design simulations are used to decouple the bulk- and surface-limited lifetimes of thin kerfless silicon wafers in a single measurement. A range of sample conditions are studied. It is observed that the technique can successfully provide reasonable upper and lower limits to the bulk and surface recombination parameters for thin kerfless silicon wafers.by Sin Cheng Siah.S.M