H L Das
Articles written in Bulletin of Materials Science
Volume 23 Issue 4 August 2000 pp 313-317 Thin Films
Thermally evaporated ZnSe thin films deposited on glass substrates within substrate temperatures (
Volume 26 Issue 6 October 2003 pp 613-617 Thin Films
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 (𝑉𝑡) 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 103/T plots are found to be within 0.60–0.37 eV. Using the relevant SCLC theory, the carrier concentration, 𝑛0, total trap concentration, 𝑁t, and the ratio of free charge to trapped charge, 𝜃 , have been calculated and correlated with ambient temperature and intensity of illumination.
Volume 29 Issue 1 February 2006 pp 11-14 Semiconductors
Photoconductivity of thermally evaporated ZnTe thin films was studied at different elevated temperatures. A gap type cell configuration with Al electrodes on glass substrates was used. The conductivity was found to obey two distinct conduction mechanisms within the region of applied fields. At low fields the photoconduction is ohmic and at high fields it is of Poole–Frenkel type. With increase of ambient temperatures, the Poole–Frenkel conductivity regions were found to extend to lower fields. The temperature dependence of dark conductivity also was found to be of similar nature.
Volume 29 Issue 1 February 2006 pp 15-16 Semiconductors
Zinc telluride thin films have been grown at room temperature and higher temperature substrates by thermal evaporation technique in a vacuum of 10-6 torr. A main peak in the photocurrent is observed at 781 nm (1.58 eV) with two lower amplitude peaks on the lower wavelength side and one on higher wavelength side. The evaluated thermal activation energy is found to correspond well with the main spectral peak. From these studies it can be inferred that temperatures up to 453 K is still in the extrinsic conductivity region of the studied ZnTe thin films.
Volume 42 | Issue 6
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