We have observed for the first time conductivity fluctuations in the persistent photoconductivity mode in II-VI mixed crystals with the magnitude following the percolation approach as ~ T — T, ~ s, where T, is the percolation threshold temperature. Experimental results have demonstrated that the random local-potential fluctuations induced by compositional fluctuations are responsible for the pe...

Single Crystals of L-lysine sulphate (abbreviated as LLS), a semiorganic nonlinear (NLO) materials have been successfully grown by slow solvent evaporation solution growth technique at room temperature. Solubility curve of LLS has been determined in mixed solvent of acetone and water. The grown crystal is characterized by single crystal X-ray diffraction (XRD) and Fourier transform infrared spe...

Light exposure usually causes an increase in photoconductivity perovskite semiconductors. However, we report here light-induced negative photoconductivity, followed by slow dark self-recovery a lead-free Cs3Bi2Br9 single crystal. Femtosecond transient reflection (fs-TR) spectroscopy studies further reveal hole self-trapping at the Vk center (Br2– dimer) midband states of this vacancy-ordered pe...

Title of Dissertation: STUDIES OF NEAR-FIELD NONLINEAR OPTICAL IMAGING OF THIN FILMS AND TRANSIENT PHOTOCONDUCTIVITY IN CONJUGATED POLYMERS Hongye Liang, Doctor of Philosophy, 2005 Directed By: Professor Chi Hsiang Lee Professor Christopher Davis Department of Electrical and Computer Engineering The dissertation is composed of two parts: 1) near-field nonlinear optical studies of ferroelectric ...

Graphene is a promising candidate for optoelectronic applications such as photodetectors, terahertz imagers and plasmonic devices. The origin of the photoresponse in graphene junctions has been studied extensively and is attributed to either thermoelectric or photovoltaic effects. In addition, hot carrier transport and carrier multiplication are thought to play an important role. Here, we repor...

The transient photoconductivity of blends of a highly soluble C60 derivative ~PCBM! and a dialkoxyphenylene-vinylene polymer ~MDMO-PPV! has been studied using the electrodeless flash-photolysis timeresolved microwave conductivity technique ~FP-TRMC!. Films approximately 100 nm thick on a quartz substrate were prepared by spin-coating PCBM/PPV solutions with PCBM weight fractions (WPCBM) from 0....

Cadmium Selenide (CdSe) thin films were synthesized by chemical bath deposition (CBD) method. The XRD, SEM, UV-Visible absorption spectrum, dielectric studies and photoconductivity measurements were used to characterize the CdSe films. The X-ray diffraction (XRD) is used to examine the structure of CdSe thin film. The surface morphology of the film was analyzed using Scanning Electron Microscop...