Study on field-effect transistors ... Transistor operation in Si MOS field-effect transistor .....2...

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Transcript of Study on field-effect transistors ... Transistor operation in Si MOS field-effect transistor .....2...

  • 2013, August

    Xuexia He

    Study on field-effect transistors and

    superconductors with phenacene

    molecules

    Graduate School of Natural Science

    and Technology

    (Doctor’s Course)

    OKAYAMA UNIVERSITY

  • Contents

    Abstract ......................................................................................................................................i

    Chapter 1. Introduction to recent organic field-effect transistors and aim of this study ........ 1

    1-1.Basic principle of field-effect transistor ............................................................................. 1

    1-2. Transistor operation in Si MOS field-effect transistor ....................................................... 2

    1-3. History of development of field-effect transistor ................................................................ 3

    1-4. Fundamental principle of organic field-effect transistor.................................................... 4

    1-5. A brief history of organic field-effect transistor................................................................. 5

    1-6. A new type of organic field-effect transistor with phenacene molecules ............................. 7

    1-7. Interesting physical properties of phenacene molecules .................................................... 8

    1-8. Motivation and aim of this study ....................................................................................... 9

    References ............................................................................................................................ 11

    Chapter 2. Crystal growth of phenacene molecules and topological images of crystals ....... 25

    2-1. Growth of phenacene single crystals ............................................................................... 25

    2-2. Melt growth method for single crystal growth ................................................................. 26

    2-3. Solution process for single crystal growth ...................................................................... 27

    2-4. Physical vapour transport method for single crystal growth............................................ 27

    2-5. Physical vapour transport method used in this study ....................................................... 28

    2-6. Optical microscope images of phenacene single crystals ................................................. 29

    2-7. Atomic force microscope (AFM) images of phenacene single crystals ............................. 30

    2-8. X-ray diffraction patterns for [6]phenacene and [7]phrnacene single crystals ................ 31

    References ............................................................................................................................ 33

    Chapter 3. Electronic structures of phenacene single crystals ............................................... 47

    3-1. Electronic structures of phenacene molecules determined by photoelectron yield

    spectroscopy and optical absorption under atmospheric condition ......................................... 47

  • 3-2. Electronic structures of phenacene molecules determined by ultra-high vacuum

    photoemission spectroscopy................................................................................................... 48

    3-3. Angle-resolved photoemission spectroscopy (ARPES) of picene solids ............................ 49

    References ............................................................................................................................ 51

    Chapter 4. Theoretical bases for FET .................................................................................... 59

    4-1. Explanation of technical terms in FET ............................................................................ 59

    4-1-1. Field-effect mobility ................................................................................................ 59

    4-1-2. Threshold voltage and on-off ratio ........................................................................... 60

    4-1-3. Subthreshold swing ................................................................................................. 61

    4-2. Theoretical background of FET ...................................................................................... 61

    4-3. Evaluation of carrier injection barrier height ................................................................. 63

    References ............................................................................................................................ 65

    Chapter 5. Fundamental FET characteristics of phenacene single crystal FETs.................. 73

    5-1. Common experimental techniques used in chapters 5 to 11 ............................................. 73

    5-2. Fundamental FET characteristics of picene single crystal FET ....................................... 75

    5-2-1. Introduction ............................................................................................................ 75

    5-2-2. Experimental section ............................................................................................... 76

    5-2-3. Results and discussion ............................................................................................. 77

    5-3. Fundamental FET characteristics of [6]phenacene and [7]phenacene single crystal FETs

    ............................................................................................................................................. 78

    5-3-1. Introduction ............................................................................................................ 78

    5-3-2. Experimental section ............................................................................................... 78

    5-3-3. Results and discussion ............................................................................................. 79

    5-4. Conclusion on fundamental FET characteristics ............................................................. 80

    References ............................................................................................................................ 81

  • Chapter 6. Interface modification with electron acceptor and donor in phenacene single

    crystal FETs ............................................................................................................................ 93

    6-1. FET characteristics of phenacene single crystal FETs in which electron acceptor or donor

    is inserted .............................................................................................................................. 93

    6-1-1. Introduction ............................................................................................................ 93

    6-1-2. Experimental ........................................................................................................... 94

    6-1-3. Results and discussion ............................................................................................. 95

    6-2. FET characteristics of [7]phenacene single crystal FETs in which Et2TCNQ is inserted:

    the observation of excellent FET characteristics .................................................................... 98

    6-3. Conclusion ..................................................................................................................... 98

    References ............................................................................................................................ 99

    Chapter 7. Systematic control of hole-injection barrier height with electron donors and

    acceptors in [7]phenacene single crystal EFTs ..................................................................... 109

    7-1. Introduction ................................................................................................................. 109

    7-2. Experimental ................................................................................................................ 110

    7-3. Results and Discussion ................................................................................................. 111

    7-3-1. Evaluation of in [7]phenacene single crystal FETs with / without insertion

    materials ......................................................................................................................... 111

    7-3-2. Variation of for insertion materials with different redox potentials ............. 113

    7-3-3. Temperature dependence of and the distinction of Schottky barrier and

    tunnelling barrier ............................................................................................................ 114

    7-3-4. VG dependence of and influence of accumulated holes in channel range ..... 115

    7-3-5. A correlation between FET parameters and Eredox .................................................. 116

    7-3-6. Effect of crystal thickness on hole-injection barrier height ..................................... 118

    7-4. Conclusion ................................................................................................................... 119

    References .......................................................................................................................... 120

  • Chapter 8. Low voltage operation