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Title: Two dimensional numerical simulations of carrier dynamics during time-resolved photoluminescence decays in two-photon microscopy measurements in semiconductors

We use two-dimensional numerical simulations to analyze high spatial resolution time-resolved spectroscopy data. This analysis is applied to two-photon excitation time-resolved photoluminescence (2PE-TRPL) but is broadly applicable to all microscopic time-resolved techniques. By solving time-dependent drift-diffusion equations, we gain insight into carrier dynamics and transport characteristics. Accurate understanding of measurement results establishes the limits and potential of the measurement and enhances its value as a characterization method. Diffusion of carriers outside of the collection volume can have a significant impact on the measured decay but can also provide an estimate of carrier mobility as well as lifetime. In addition to material parameters, the experimental conditions, such as spot size and injection level, can impact the measurement results. Although small spot size provides better resolution, it also increases the impact of diffusion on the decay; if the spot size is much smaller than the diffusion length, it impacts the entire decay. By reproducing experimental 2PE-TRPL decays, the simulations determine the bulk carrier lifetime from the data. The analysis is applied to single-crystal and heteroepitaxial CdTe, material important for solar cells, but it is also applicable to other semiconductors where carrier diffusion from the excitation volume could affect experimental measurements.
Authors:
; ; ;  [1] ;  [1] ;  [2]
  1. National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22494677
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 4; Other Information: (c) 2015 U.S. Government; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CADMIUM TELLURIDES; CARRIER LIFETIME; CARRIER MOBILITY; COMPUTERIZED SIMULATION; DIFFUSION EQUATIONS; DIFFUSION LENGTH; EXCITATION; MICROSCOPY; MONOCRYSTALS; PHOTOLUMINESCENCE; PHOTONS; SEMICONDUCTOR MATERIALS; SOLAR CELLS; SPATIAL RESOLUTION; SPECTROSCOPY; TIME DEPENDENCE; TIME RESOLUTION; TWO-DIMENSIONAL CALCULATIONS