Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Thermal evaporation

Behavior of A.C conductivity and Complex dielectric constant of ZnS Thin Films

Zainab Taha A; Khitam S. Shaker; Suaad S. Shaker; Raghdaa Hameed Hani

Engineering and Technology Journal, 2015, Volume 33, Issue 4, Pages 745-752

The effect of temperature on dielectric properties of the prepared ZnS thin films by chemical bath deposition at film thickness (200) nm deposited at substrate temperature 333 K, was measured at frequency range (0.04-10 MHz) in the temperature range (298- 473) K .The temperature – dependent of electrical conductivity, the real and imaginary parts of the complex dielectric constant are calculated at the selected frequencies. The frequency exponent n, and the activation energy, Ea, are determined. The a.c. conduction mechanism of ZnS films has been explained on the basis of hopping of charge carriers.

Optoelectronic Properties of CdSe/Si Heterojunction

Waseem Najeeb Ibrahim

Engineering and Technology Journal, 2012, Volume 30, Issue 12, Pages 2138-2149

In this paper n-CdSe/p-Si heteroj unction photodetector was fabricated by
thermal-evaporation technique of CdSe thin film grown onto single crystalline Si
substrate . The energy gap of CdSe film was estimated from transmittance spectra
and found to be (1.89 eV) . The temperature dependence of Seebeck coefficient
was studied . The conductivity of CdSe thin film is n-type and the value of
activation energy is (0.59 eV). Heterojunction properties included dark and
illuminated current-voltage (I-V) and capacitance-voltage (C-V) characteristics.
From I-V plot, junction ideality factor for heterojunction was calculated to be
1.43, and providing information about the current transport mechanism. The linear
variation of the experimental curve C-2 vs. V is indicative of the presence of
abrupt heterojunction and it used to determine the experimental value of built-injunction
potential Vbi . From illuminated I-V plot at different intensity levels
(90,180,240) mW/cm2 , the linearity behavior of CdSe/Si heterojunction was
investigated .