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4-gate PICTS spectra for Pb-doped and Se-doped TlBr, measured from 90 to 250 K for en , p = 585 s−1. V+ and V− denote the sign of the voltage applied to the illuminated contact. The gain settings of the current amplifier during the measurement indicate the change in photoconductivity of each sample with temperature.
Arrhenius plots for the observed levels, showing data points and the resulting linear fits. The slope of the lines represents the activation energy of each trap. The apparent capture cross section is determined from the y-intercept.
CL spectra for the TlBr samples taken at 5 K. The dashed lines show a deconvolution of the two peaks evident in the Pb-doped spectrum between 1.8 and 2.5 eV.
A schematic energy level diagram showing mid-gap states related to Pb- and Se-dopants in TlBr detected by PICTS. Curved arrows indicate optically active transitions measured with CL.
Plots of microwave photoconductivity transient data with single exponential fits (black dashed lines) showing the ambipolar lifetime in the three TlBr samples. The different laser powers used reflect the differing efficiencies of carrier generation with sub-bandgap light in the three samples. The curves are vertically offset for clarify.
Activation energies and capture cross sections for the resolved deep levels.
Comparison of PICTS and CL data. The energy offset is calculated from the 2.68 eV indirect bandgap of TlBr.
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