I= STUDYING THE EFFECT OF DEPOSITION CONDITIONS AND DOPING ON THE PROPERTIES OF ZnTe THIN FILMS
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Title of Thesis
STUDYING THE EFFECT OF DEPOSITION CONDITIONS AND DOPING ON THE PROPERTIES OF ZnTe THIN FILMS
Author(s)
Akram K.S Aqili
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Session
2002
Subject
Physics
Number of Pages
104
Keywords (Extracted from title, table of contents and abstract of thesis)
znte thin film, deposition conditions, doping, thermal evaporation, transmittance spectra, sb doping, empa, deposition process, sem

Abstract
ZnTe films have been prepared by two-sourced thermal evaporation. The effects of the deposition parameters, such as evaporation rate and substrate temperature, on the optical, and structural properties as well as the resulting composition of the films were studied. The optical parameters of the films ( Le. refractive index, absorption coefficient, optical band gap and film thickness) were calculated from the normal transmittance data. A 'model was proposed for the calculation of the optical parameters from the transmittance spectra. The transmittance formula, derived for using in the proposed model, includes most of the parameters affecting the transmittance spectra, i.e finite substrate thickness. absorption of the substrate, thickness irregularity of the film surface, reflection from the back side of the substrate in addition to the refractive index and absorption of the film itself. The model was checked by theoretically simulated transmittance spectra as well as experimental data, and good accuracy was confirmed. Comparison of fitting of different transmittance formulas, as well as different models for the refractive index and the absorption coefficient also were done.

For reducing the resistivity of ZnTe films. Doping with different materials were performed. Cu and Ag doping was done by an ion exchange process, which is by immersion of the ZnTe films into a copper nitrate solution (in case of Cu doping). The solution temperature was fixed, and the effect of the immersion time and post vacuum heat treatment, on the physical properties and the composition of the resulting films was studied.

Three sourced evaporation from the elemental sources, was used for Sb doping. The resulting composition of the films was controlled by controlling the elements flux ratio as well as the substrate temperature. The structure of the films was studied by X-ray diffraction and the composition of the resulting films was measured by electron microprobe analysis (EMPA).
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1617.76 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
184.49 KB
2 1 Introduction 1
128.3 KB
  1.1 Deposition Process 1
  1.2 Vacuum Evaporation 2
  .1.3 Znte Films 5
3 2 Characterization Methods 10
152.6 KB
  2.1 X-Ray Diffraction 10
  2.2 SEM And EMPA 11
  2.3 Resistivitly And Conduction Mechanism 12
  2.4 Optical Constants And Optical Band OAP 16
4 3 Optical Calculations 20
349.83 KB
  3.1 Model For Determination Of Thickness, Refractive Index And Thickness Irregularity 20
  3.2 Approximation Approach 33
  3.3 Nonlinear Curve Fitting 35
5 4 Experimental Setup 42
88.86 KB
  4.1 Films Deposition Technique 42
  4.2 Glass Substrates 44
  4.3 Optical Transmission 44
  4.4 X-Ray Diffraction 44
  4.5 SEM And EMPA 45
  4.6 Resistivity Measurements 45
6 5 ZnTe Films By Two Sourced Thermal Evaporation 46
235.69 KB
  5.1 Experimental 46
  5 .2 Results 48
  5.3 Discussion 58
7 6 Properties Of Copper Doped ZnTe Thin Films By Immersion In Cu Solution 60
176.6 KB
  6.1 Experimental Procedure 60
  6.2 Results And Discussion 62
8 7 Properties Of Silver Doped ZnTe Thin Films By An Ion Exchange Process 72
169.24 KB
  7 .1 Experimental 72
  7.2 Results And Discussion 73
9 8 Antimony Doped ZnTe Films 82
228.71 KB
  8.1 Experimental Procedure 82
  8.2 Results And Discussion 83
10 9 Conclusions 94
39.23 KB