tesi R. Miscioscia.pdf - EleA@UniSA

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130 Exceptions in morphology-mobility relationship ln (μ/μ*) 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 -4.5 -5.0 -5.5 -6.0 1000/T MN VGSV GS -16V -15V -14V -13V -12V -11V -10V -9V -8V -7V PMMA 225nm as-is -6.5 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 1000/T (K -1 ) figure 14: Arrhenius plots of mobility of PMMA 225nm device at different VGS voltages and their Meyer-Neldel fit necessary to extract the activation energy and the mobility prefactor. Furthermore, from the slope of the fitting lines in Arrhenius plots, it has been possible to extract the activation energy (Ea) of the carrier trapping/release process, Ea(VGS), which has been compared in figure 15. V GS
Chapter 4 131 Ea(eV) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 PFTEOS:TEOS/PMMA 273nm PFTEOS:TEOS 270nm PMMA 115nm PMMA 225nm PMMA 400nm -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 V GS (V) figure 15: Activation Energy (Ea(VGS)) graph for charge mobility in considered samples versus VGS gate bias. As it can be seen in figure 15, in every sample, activation energy decreases with gate bias but the relationship between sample’s physical features and activation energy appears unclear and all the curves tend to collapse, at high gate fields to a common value of 0.12eV of activation energy and a precise trend of TMN is not identified. Our hypothesis is that a thermally-activated non-ideality phenomenon is hiding the real thermal behavior of charge mobility from our analysis. Between the main causes of device’s drift from the nominal behavior there are the gate leakages as we seen in chapter 3. Nevertheless it cannot easily be eliminated by means of the circuital equivalent we proposed in previous works [24] because the wide variation of mobility with gate field cannot be addressed in the model without losing the physical meaning of the extracted parameters. This is due to the introduction of an additional variable in the fitting of output curves in the triode region. Thus, it appears clear that we have to extract the channel current Ich from the measured drain current ID and gate leakage IG by following an alternative path. For these reasons we decided to change the approach and to apply the Esseni’s [26] method to clear the
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Università degli Studi di Salerno
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Acknowledgments It is a pleasure to
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In loving memory of my uncle, Profe
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Introduction Nowadays, it has becom
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Introduction 3 The drawbacks of org
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Introduction 5 Artificial Skin (OTF
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Introduction 7 structure has been d
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Chapter 1 Working principles An Org
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Chapter 1 11 1.1 A model for DC beh
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Chapter 1 13 hp. 4) Decoupling betw
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Chapter 1 15 figure 2: integration
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Chapter 1 17 eq. 11 − = Then, bei
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Chapter 1 19 The formula in eq. 18
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Chapter 1 21 and behaves as a resis
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Chapter 1 23 eq. 22 I DS = μ C ins
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Chapter 1 25 In eq. 27, kB is the B
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Chapter 1 27 eq. 30 · Thu
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Chapter 2 A survey on the state of
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Chapter 2 31 emphasizing the role p
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Chapter 2 33 Only after those years
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Chapter 2 35 In fact, usually the m
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Chapter 2 37 Examples of top-gate b
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Chapter 2 39 deposition process of
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Chapter 2 41 region is patterned by
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Chapter 2 43 figure 11: Non-Relief-
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Chapter 2 45 factor analysing, in p
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Chapter 2 47 In literature results,
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Chapter 2 49 It is clear that the c
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Chapter 2 51 In figure 17 the impro
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Chapter 2 53 figure 19: OFET trans-
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Chapter 2 55 figure 22: Comparison
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Chapter 2 57 channel and gate in Pe
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Chapter 2 59 figure 28: Pentacene b
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Chapter 2 61 figure 31: OTFT realiz
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Chapter 2 63 materials, the higher
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Chapter 2 65 The effect of the barr
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Chapter 2 67 figure 36: potential p
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Chapter 2 69 From table 2, it is ea
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Chapter 2 71 thermal-budget treatme
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Chapter 2 73 in particular in OLEDs
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Chapter 2 75 One interesting charac
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Chapter 2 77 figure 48: electrical
Page 85 and 86: Chapter 2 79 The research on the OE
Page 87 and 88: Chapter 2 81 photolysis). In this p
Page 89 and 90: Chapter 2 83 [26] Facchetti, Wasiel
Page 91 and 92: Chapter 3 Gate-leakages in polymeri
Page 93 and 94: Gate-leakages 87 determined by XRD
Page 95 and 96: Gate-leakages 89 The results are:
Page 97 and 98: Gate-leakages 91 It has to be consi
Page 99 and 100: Gate-leakages 93 figure 8: Output c
Page 101 and 102: Gate-leakages 95 figure 12: electri
Page 103 and 104: Gate-leakages 97 3.4 Advanced circu
Page 105 and 106: Gate-leakages 99 figure 16: SEM ima
Page 107 and 108: Gate-leakages 101 modeled with a co
Page 109 and 110: Gate-leakages 103 eq. 11 • Shadow
Page 111 and 112: Gate-leakages 105 References [1] R.
Page 113 and 114: Chapter 4 Morphology-mobility relat
Page 115 and 116: Chapter 4 109 insulators to increas
Page 117 and 118: Chapter 4 111 3.2 General device st
Page 119 and 120: Chapter 4 113 Pentacene islands are
Page 121 and 122: Chapter 4 115 For the preparation o
Page 123 and 124: Chapter 4 117 figure 3: PFTEOS:TEOS
Page 125 and 126: Chapter Chapter 4 4 119 (a): (a):
Page 127 and 128: Chapter 4 121 3.4 Device’s charac
Page 129 and 130: Chapter 4 123 mobility with the dim
Page 131 and 132: Chapter 4 125 As it can be observed
Page 133 and 134: Chapter 4 127 eq. 4 Where r
Page 135: Chapter 4 129 3.4.3 Thermal charact
Page 139 and 140: Chapter 4 133 I D (A) 100.0n 80.0n
Page 141 and 142: Chapter 4 135 μ (cm 2 V -1 s -1 )
Page 143 and 144: Chapter 4 137 T MN (K) 2400 2200 20
Page 145 and 146: Chapter 4 139 Such results, supply
Page 147 and 148: Chapter 4 141 References [1] O. D.
Page 149 and 150: Chapter 4 143 [26] P. Palestri, D.
Page 151 and 152: Conclusions In this PhD dissertatio
Page 153 and 154: Introduction 147 characterizing mor
Page 155 and 156: Table of acronyms and symbols Symbo
Page 157: Table of acronyms and symbols _____
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