Thermally evaporated ZnSe thin films deposited on glass substrates within substrate temperatures (T s ) at 303 K-623 K are of polycrystalline nature having f.c.c. zincblende structure. The most preferential orientation is along [111] direction for all deposited films together with other abundant planes [220] and [311]. The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of preferred orientation in the film are calculated and correlated with T s .

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The current (I)-voltage (V) characteristics of thermally evaporated CdSe thin films having thickness in the range 850-3000 Å and deposited within the substrate temperature of 303-573 K show nearly linear dependence at low voltage and afterwards a non-linear behaviour at higher voltage range. A detailed study of I-V curves in dark and under illumination clearly reveals the mechanism as ohmic at low voltage and that of trap limited space charge limited conduction (SCLC) at higher voltage. The transition voltage (V t) from ohmic to SCLC is found to be quite independent of ambient temperature as well as intensity of illumination. SCLC is explained on the basis of the exponential trap distribution in CdSe films. Trap depths estimated from the ln I vs 10 3 /T plots are found to be within 0⋅ ⋅60-0⋅ ⋅37 eV. Using the relevant SCLC theory, the carrier concentration, n 0 , total trap concentration, N t , and the ratio of free charge to trapped charge, θ θ, have been calculated and correlated with ambient temperature and intensity of illumination.

In this paper, a systematic investigation of frequency response of CdS and CdS:Cu quantum dot devices, following microwave-assisted synthesis, is presented. Phase of the output relative to the input as a function of frequency is also recorded to have some insight into the observed low-pass filter characteristics of the as-fabricated devices. The as-fabricated quantum dot devices are found to have all the characteristics of a classical low-pass filter with optimization of gain, phase shift and cut-off frequency in the band-gap range of '2.5À2.6' eV. The as-fabricated devices are tested for demodulation and satisfactory operation is obtained. This suggests for employing such nanoscale devices in the field of communications.