tesi R. Miscioscia.pdf - EleA@UniSA

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12 Working Principles In figure 1, we named tch the channel thickness, tox the insulator thickness, VGS the gate to source voltage, V(x) the voltage along the channel starting from the source’s position. hp. 2) Source and drain are considered as metal-semiconductor contacts having an ohmic behavior. In this case, their electrical resistance is hypothesized to be constant with the applied voltage. For a contact between a metal and a n-type semiconductor this basic condition is reached when the energetic barrier φB from metal work-function φM to semiconductor material electron affinity χS is zero or negative being φB = φM - χS where φM is evaluated as the difference between the vacuum level (E0) and the Fermi level (EF) in the metal and χS is the difference between E0 and the conduction band level in the semiconductor EC. More precisely, φM ≡ E0 - EF(Metal) χS ≡ E0 - EF(Semiconductor) for a metal/(n-type semiconductor) junction the barrier is: φB = φM - χS and for a metal/(p-type semiconductor) junction: φB = (EG + χS) - φM Being EG = EC - EV the semiconductor’s band-gap. In this case the barrier is the distance of the metal’s Fermi level from valence band of the semiconductor. hp. 3) Carrier diffusion effects are neglected and, for the matter of simplicity, n-type conduction hypothesized neglecting p-type carrier concentrations and currents. Once neglected diffusion currents, just the drift contribution jt to current density will be considered.
Chapter 1 13 hp. 4) Decoupling between injection mechanisms and field-effect. The charge density injected from source to channel nDS(x,y) will be considered independent from the charge density induced in the channel by the field effect nG(x,y) due to the gate potential VGS and will be treated separately. hp. 5) Charge mobility µ will be thought constant in the semiconductor material, and then its value will be considered in first approx. uniform and independent from applied voltages VGS and VDS. hp. 6) Gradual channel approximation (GCA). The rate of variation of the lateral field E x within the channel is considered much smaller than the rate of variation of the vertical fieldE y . An easy case in which this condition can be reached is when the channel length is assumed much higher than insulator thickness and the potentials VGS, VDS in the same range. Then: t OX ∂E x ∂x
Page 1 and 2: Università degli Studi di Salerno
Page 3 and 4: Acknowledgments It is a pleasure to
Page 5 and 6: In loving memory of my uncle, Profe
Page 7 and 8: Introduction Nowadays, it has becom
Page 9 and 10: Introduction 3 The drawbacks of org
Page 11 and 12: Introduction 5 Artificial Skin (OTF
Page 13 and 14: Introduction 7 structure has been d
Page 15 and 16: Chapter 1 Working principles An Org
Page 17: Chapter 1 11 1.1 A model for DC beh
Page 21 and 22: Chapter 1 15 figure 2: integration
Page 23 and 24: Chapter 1 17 eq. 11 − = Then, bei
Page 25 and 26: Chapter 1 19 The formula in eq. 18
Page 27 and 28: Chapter 1 21 and behaves as a resis
Page 29 and 30: Chapter 1 23 eq. 22 I DS = μ C ins
Page 31 and 32: Chapter 1 25 In eq. 27, kB is the B
Page 33 and 34: Chapter 1 27 eq. 30 · Thu
Page 35 and 36: Chapter 2 A survey on the state of
Page 37 and 38: Chapter 2 31 emphasizing the role p
Page 39 and 40: Chapter 2 33 Only after those years
Page 41 and 42: Chapter 2 35 In fact, usually the m
Page 43 and 44: Chapter 2 37 Examples of top-gate b
Page 45 and 46: Chapter 2 39 deposition process of
Page 47 and 48: Chapter 2 41 region is patterned by
Page 49 and 50: Chapter 2 43 figure 11: Non-Relief-
Page 51 and 52: Chapter 2 45 factor analysing, in p
Page 53 and 54: Chapter 2 47 In literature results,
Page 55 and 56: Chapter 2 49 It is clear that the c
Page 57 and 58: Chapter 2 51 In figure 17 the impro
Page 59 and 60: Chapter 2 53 figure 19: OFET trans-
Page 61 and 62: Chapter 2 55 figure 22: Comparison
Page 63 and 64: Chapter 2 57 channel and gate in Pe
Page 65 and 66: Chapter 2 59 figure 28: Pentacene b
Page 67 and 68: Chapter 2 61 figure 31: OTFT realiz
Page 69 and 70:
Chapter 2 63 materials, the higher
Page 71 and 72:
Chapter 2 65 The effect of the barr
Page 73 and 74:
Chapter 2 67 figure 36: potential p
Page 75 and 76:
Chapter 2 69 From table 2, it is ea
Page 77 and 78:
Chapter 2 71 thermal-budget treatme
Page 79 and 80:
Chapter 2 73 in particular in OLEDs
Page 81 and 82:
Chapter 2 75 One interesting charac
Page 83 and 84:
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 and 136:
Chapter 4 129 3.4.3 Thermal charact
Page 137 and 138:
Chapter 4 131 Ea(eV) 0.50 0.45 0.40
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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