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Title of Thesis

Abid Ali
Institute/University/Department Details
Department of Physics / Quaid-i-Azam University of Islamabad
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
cd-based ii-vi thin films, ii-vi compound semiconductors thin films, glass substrates, cdte thin films

The II-VI compound semiconductors thin films have been prepared by different methods such as electron beam vacuum evaporation, closed space sublimation and two-sourced thermal evaporation. The choice of the deposition method was based on the quality of the films required for specific application. In this research work mainly two-source evaporation technique is applied for sample preparation.

The effects of deposition parameters, such as substrate and source temperature and annealing of the film, on the structural, optical and electrical properties have been studied. The structure' and composition of the films were studied by X-ray diffraction and Energy dispersive x-ray analysis respectively. Optical parameters such as refractive index, absorption coefficient, film thickness and optical band gap, were calculated from the optical transmission spectra recorded by spectrophotometer.

The impact of evaporation rates of Cd and Te on CdTe thin films deposited by two sourced evaporation technique and their post doping effects arising from the diffusion of Cu and Ag to understand changes in the ,film properties were also studied.

The ion exchange process is a very simple, and low cost technique. In this technique the dopant has to be in the form of ion in a solution, where the pre-prepared films are to be immersed, i.e. Ag(NO3) solution in case of silver doping and CU(NO3) solution in case of copper doping. The ion exchange parameters such as solution temperature, concentration and immersion time, and its effect on the speed of the process and further on the status of the resulting films was carefully determined and analyzed. Also the effect of post heat treatment, on the physical properties and the composition of the resulting films were studied. Ag and Cu doping of the CdTe thin films were successfully achieved.

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2615.86 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
249.58 KB
2 0 Introduction To Thin Films 1
249.58 KB
  1.1 Thin Film Deposition 3
  1.2 Glass Substrates And Their Cleaning Procedures 6
  1.3 Coating Materials 11
  1.4 Deposition Parameters 9
  1.5 Frenkel Theory Of Adsorption 10
  1.6 Semiconductor Materials 11
  1.7 Ohmic Contact 13
  1.8 Motivation For This Work 13
  1.9 References 14
3 2 Characterization Techniques 19
538.03 KB
  2.1 Scanning Electron Microscopy 19
  2.2 Detection Of Backscattered Electrons 20
  2.3 X-Ray Crystallography 21
  2.4 Optical Spectroscopy 23
  2.5 Sheet Resistance 33
  2.6 Thin Film Thickness Monitor 34
  2.7 Vacuum Pumps 35
  2.8 References 38
4 3 Experimental Setup 40
193.52 KB
  3.1 Two Source Evaporation Technique 40
  3.2 Glass Substrates 42
  3.3 Resistivity Measurements 43
5 4 Impact Of Evaporation Rates Of Cd And Te On Cdte Thin Films 49
367.26 KB
  4.1 Experimental Properties 49
  4.2 Structural Properties 50
  4.3 Optical Properties 54
  4.4 Electrical Properties 59
  4.5 References 61
6 5 Cu-Containing Low Resistivity Cd Te Thin Films 62
357.65 KB
  5.1 Experimental Procedure 62
  5.2 Structural Properties 64
  5.3 Optical Properties 66
  5.4 Electrical Properties 70
  5.5 References 70
7 6 Ag Doped Cd Te Thin Films 75
189.12 KB
  6.1 Experimental Procedure 75
  6.2 Results And Discussion 75
  6.3 References 82
8 7 Comparison Of Cd Te/ Hg Te Thin Films 83
371.69 KB
  7.1 Introduction 83
  7.2 Experimental Techniques 84
  7.3 Structural Properties 87
  7.4 Optical Properties 89
  7.5 Electrical Properties 92
  7.6 References 95
  7.7 Conclusion 96