Acknowledgments ............................................... vii
1 Defect States Spectroscopy in Amorphous Semiconductors ....... 1
1.1 Introduction ............................................ 1
1.2 General Principles ...................................... 2
2 Thermally Stimulated Depolarization Currents in
Amorphous Chalcogenides ..................................... 21
2.1 Background ............................................. 21
2.2 Theoretical Background ................................. 23
2.3 TSDCs in Se-Based Amorphous Semiconductors:
Experimental Results ................................... 28
2.4 TSDC in Pure Selenium .................................. 29
2.5 TSDC in As(Sb)xSe1-x, Alloys ............................ 31
3 Carrier Transport Processes in Amorphous Solids ............. 37
3.1 Background ............................................. 37
3.2 Experimental Techniques for the Measurement of
Carrier Mobility ....................................... 39
3.3 Significance of Carrier Transport Data in Various
Applications ........................................... 42
3.4 Conventional Dispersion Behavior ....................... 43
3.5 Anomalous Dispersive Characteristics ................... 44
4 Time-of-Flight Experiments in Amorphous Chalcogenide
Semiconductors .............................................. 53
4.1 An Apparatus for IFTOF Measurements .................... 56
4.2 XTOF Technique ......................................... 61
4.3 TOF Measurements in Selenium-Based Amorphous
Multilayer Photoconductors ............................. 66
5 Xerographic Spectroscopy of States in Mobility Gap .......... 79
5.1 Schematic Overview of the Xerographic Photocopying
Process ................................................ 80
5.2 Xerography in Animation ................................ 83
5.3 Xerographic Dark Decay and Photoinduced Effects ........ 85
6 Photoinduced Effects on States in the Mobility Gap .......... 95
6.1 Introduction ........................................... 95
6.2 Steady-State Photocurrents ............................. 95
6.3 Light-Induced Effects on Photocurrent Transients ....... 96
7 Spectroscopic Studies of Gap States and Laser-Induced
Structural Transformations in Se-Based As-Free Amorphous
Semiconductors ............................................. 103
7.1 Preparation of Amorphous Films: Essential Results
and Interpretation .................................... 103
7.2 The Basic Properties .................................. 105
7.3 Dark Discharge ........................................ 107
7.4 Transient Photoconductivity ........................... 108
7.5 Photoinduced Discharge Characteristics ................ 109
7.6 Optical Properties .................................... 114
7.7 Structural Transformation ............................. 116
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