Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II

Wide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields, including power electronics, illumination, and sensors. This reprint collects the 23 papers covering the full spectrum of the above applications and providing contributions from the on-going research at different levels, from materials to devices and from circuits to systems

Integrated Circuits/Microchips

With the world marching inexorably towards the fourth industrial revolution (IR 4.0), one is now embracing lives with artificial intelligence (AI), the Internet of Things (IoTs), virtual reality (VR) and 5G technology. Wherever we are, whatever we are doing, there are electronic devices that we rely indispensably on. While some of these technologies, such as those fueled with smart, autonomous systems, are seemingly precocious; others have existed for quite a while. These devices range from simple home appliances, entertainment media to complex aeronautical instruments. Clearly, the daily lives of mankind today are interwoven seamlessly with electronics. Surprising as it may seem, the cornerstone that empowers these electronic devices is nothing more than a mere diminutive semiconductor cube block. More colloquially referred to as the Very-Large-Scale-Integration (VLSI) chip or an integrated circuit (IC) chip or simply a microchip, this semiconductor cube block, approximately the size of a grain of rice, is composed of millions to billions of transistors. The transistors are interconnected in such a way that allows electrical circuitries for certain applications to be realized. Some of these chips serve specific permanent applications and are known as Application Specific Integrated Circuits (ASICS); while, others are computing processors which could be programmed for diverse applications. The computer processor, together with its supporting hardware and user interfaces, is known as an embedded system.In this book, a variety of topics related to microchips are extensively illustrated. The topics encompass the physics of the microchip device, as well as its design methods and applications

A Vertical C60 Transistor with a Permeable Base Electrode

A high performance vertical organic transistor based on the organic semiconductor C60 is developed in this work. The sandwich geometry of this transistor, well known from organic light-emitting diodes or organic solar cells, allows for a short transfer length of charge carriers in vertical direction. In comparison to conventional organic field-effect transistors with lateral current flow, much smaller channel lengths are reached, even if low resolution and low-cost shadow masks are used. As a result, the transistor operates at low voltages (1 V), drives current densities in the range of 10 A/cm², and enables a switching speed in the MHz range. The operation mechanism is studied in detail. It is demonstrated that the transistor can be described by a nano-porous permeable base electrode insulated by a thin native aluminum oxide film on its surface. Thus, the transistor has to be understood as two metal-oxide-semiconductor diodes, sharing a common electrode, the base. Upon applying a bias to the base, charges accumulate in front of the oxide, similar to the channel formation in a field-effect transistor. Due to the increased conductivity in this region, charges are efficiently transported toward and through the pinholes of the base electrode, realizing a high charge carrier transmission. Thus, even a low concentration of openings in the base electrode is sufficient to ensure large transmission currents. The device concept turns out to be ideal for applications where high transconductance and high operation frequency are needed, e.g. in analog amplifier circuits. The full potential of the transistor is obtained if the active area is structured by an insulating layer in order to perfectly align the three electrodes. Besides that, molecular doping near the charge injecting contact is essential to minimize the contact resistance. Due to the high power density in the vertical C60 transistor, Joule self-heating occurs, which is discussed in this work in the context of organic semiconductors. The large activation energies of the electrical conductivity observed cause the presence of S-shaped current-voltage characteristics and result in thermal switching as well as negative differential resistances, as demonstrated for several two-terminal devices. A detailed understanding of these processes is important to determine restrictions and proceed with further optimizations.:CONTENTS Publications, patents and conference contributions 9 1 Introduction 13 2 Theory 19 2.1 From small molecules to conducting thin films . . . . . . . . . . . . . . . . . . . . 19 2.1.1 Aromatic hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.1.2 Solid state physics of molecular materials . . . . . . . . . . . . . . . . . . . 24 2.1.3 Energetic landscape of an organic semiconductor . . . . . . . . . . . . . . 26 2.1.4 Charge transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2.2 Semiconductor structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.2.1 Semiconductor statistics and transport . . . . . . . . . . . . . . . . . . . . 42 2.2.2 Charge injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.2.3 Limitations of the current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 2.2.4 Metal-oxide-semiconductor structures . . . . . . . . . . . . . . . . . . . . . 57 2.3 Self-heating theory of thermistor device . . . . . . . . . . . . . . . . . . . . . . . . 61 3 Organic transistors 65 3.1 The organic field-effect transistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.1.1 Basic principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.1.2 Device characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 3.1.3 Device geometries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 3.1.4 Device parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.1.5 Issues of OFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.1.6 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 3.2 Overview over vertical organic transistors . . . . . . . . . . . . . . . . . . . . . . . 76 3.2.1 VOTs with an unstructured base electrode . . . . . . . . . . . . . . . . . . . 76 3.2.2 VOTs with structured base electrode . . . . . . . . . . . . . . . . . . . . . . 79 3.2.3 Charge injection modulating transistors . . . . . . . . . . . . . . . . . . . . 82 3.2.4 Vertical organic field-effect transistor . . . . . . . . . . . . . . . . . . . . . . 85 3.2.5 Development of the scientific output . . . . . . . . . . . . . . . . . . . . . . 87 3.2.6 Competing technologies and approaches . . . . . . . . . . . . . . . . . . . 88 3.3 Vertical Organic Triodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.1 Stucture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.2 Electronic configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.3 Energetic alignment of the diodes . . . . . . . . . . . . . . . . . . . . . . . 92 3.3.4 Current flow in the on and the off-state . . . . . . . . . . . . . . . . . . . . 94 3.3.5 Definition and extraction of parameters . . . . . . . . . . . . . . . . . . . . 95 4 Experimental 101 4.1 General processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.1.1 Thermal vapor deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.1.2 Processing tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 4.1.3 Processing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 4.2 Mask setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 4.3 Measurement setups and tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.3.1 Current-voltage measurements . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.3.2 Frequency-dependent measurements . . . . . . . . . . . . . . . . . . . . . 108 4.3.3 Impedance Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 4.3.4 Ultraviolet and X-ray Photoelectron Spectroscopy . . . . . . . . . . . . . . . 110 4.3.5 Thermal imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 4.4 Materials used in C60 triodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.4.1 Buckminsterfullerene C60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.4.2 Tungsten paddlewheel W2(hpp)4 . . . . . . . . . . . . . . . . . . . . . . . . 116 4.4.3 Aluminum and its oxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 4.4.4 Spiro-TTB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4.5 Materials used in Organic Light-emitting Diodes . . . . . . . . . . . . . . . . . . . 121 5 Introduction of C60 VOTs 123 5.1 Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 5.2 Diode characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 5.3 Base sweep measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 5.4 Determination of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 5.5 Common-base connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 5.6 Output characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 5.7 Frequency-dependent measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 137 5.8 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 6 Effect of annealing 141 6.1 Charge carrier transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 6.2 Sheet resistance and transmittance of the base electrode . . . . . . . . . . . . . . 142 6.3 Investigation of morphological changes . . . . . . . . . . . . . . . . . . . . . . . . 144 6.4 Photoelectron spectroscopy of the base electrode . . . . . . . . . . . . . . . . . . 153 6.5 Influence of air exposure and annealing onto the dopants . . . . . . . . . . . . . . 159 6.6 Electrical characteristics of the diodes . . . . . . . . . . . . . . . . . . . . . . . . . 162 6.7 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 7 Working Mechanism 167 7.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 7.2 Diode characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 7.3 Simulation and modeling of the diode characteristics . . . . . . . . . . . . . . . . . 173 7.4 Interpretation of the operation mechanism . . . . . . . . . . . . . . . . . . . . . . . 181 7.5 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 8 Optimization of VOTs 183 8.1 Misalignment of the electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 8.2 Use of doping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 8.3 Variation of the intrinsic layer thickness . . . . . . . . . . . . . . . . . . . . . . . . . 190 8.4 Structuring the active area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 8.5 High-frequency operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.6 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 9 Self-heating in organic semiconductors 209 9.1 Temperature activation in C60 triodes . . . . . . . . . . . . . . . . . . . . . . . . . . 210 9.2 nin-C60 crossbar structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 9.3 Thermal switching in organic semiconductors . . . . . . . . . . . . . . . . . . . . . 216 9.4 Self-heating in large area devices: Organic LEDs . . . . . . . . . . . . . . . . . . . 218 9.5 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 10 Conclusion and Outlook 227 10.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 10.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 A Appendix 233 A.1 Appendix 1: Accuracy of the current gain . . . . . . . . . . . . . . . . . . . . . . . 233 A.2 Appendix 2: Fit of XRR measurements . . . . . . . . . . . . . . . . . . . . . . . . . 234 A.3 Appendix 3: Atomic force microscopy . . . . . . . . . . . . . . . . . . . . . . . . . 236 A.4 Appendix 4: Transmission electron microscopy . . . . . . . . . . . . . . . . . . . . 236 A.5 Appendix 5: Drift-diffusion simulation of nin devices . . . . . . . . . . . . . . . . . 239 A.6 Appendix 6: A simple parallel thermistor circuit . . . . . . . . . . . . . . . . . . . . 241 List of Figures 245 References 290In dieser Arbeit wird ein vertikaler organischer Transistor mit hoher Leistungsfähigkeit vorgestellt, der auf dem organischen Halbleiter C60 basiert. Die von organischen Leuchtdioden und organischen Solarzellen bekannte \'Sandwich’-Geometrie wird verwendet, so dass es möglich ist, für die vertikale Stromrichtung kurze Transferlängen der Ladungsträger zu erreichen. Im Vergleich zum konventionellen organischen Feldeffekttransistor mit lateralem Stromfluss werden dadurch viel kleinere Kanallängen erreicht, selbst wenn preisgünstige Schattenmasken mit geringer Auflösung für die thermische Verdampfung im Vakuum genutzt werden. Daher kann der Transistor bei einer Betriebsspannung von 1 V Stromdichten im Bereich von 10 A/cm² und Schaltgeschwindigkeiten im MHz-Bereich erreichen. Obwohl diese Technologie vielversprechend ist, fehlt bislang ein umfassendes Verständnis des Funktionsmechanismus. Hier wird gezeigt, dass der Transistor eine nanoporöse Basiselektrode hat, die durch ein natives Oxid auf ihrer Oberfläche elektrisch isoliert ist. Daher kann das Bauelement als zwei Metall-Oxid-Halbleiter-Dioden verstanden werden, die sich eine gemeinsame Elektrode, die Basis, teilen. Unter Spannung akkumulieren Ladungsträger vor dem Oxid, ähnlich zur Ausbildung eines Ladungsträgerkanals im Feldeffekttransistor. Aufgrund der erhöhten Leitfähigkeit in dieser Region werden Ladungsträger effizient zu und durch die Öffnungen der Basis transportiert, was zu hohen Ladungsträgertransmissionen führt. Selbst bei einer geringen Konzentration von Löchern in der Basiselektrode werden so hohe Transmissionsströme erzielt. Das Bauelementkonzept ist ideal für Anwendungen, in denen eine hohe Transkonduktanz und eine hohe Schaltgeschwindigkeit erreicht werden soll, z.B. in analogen Schaltkreisen, die kleine Signale verarbeiten. Das volle Potential des Transistors offenbart sich jedoch, wenn die aktive Fläche durch eine Isolatorschicht strukturiert wird, um den Überlapp der drei Elektroden zu optimieren, so dass Leckströme minimiert werden. Daneben ist die Dotierung der Molekülschichten am Emitter essentiell, um Kontaktwiderstände zu vermeiden. Aufgrund der hohen Leistungsdichten in den vertikalen C60-Transistoren kommt es zur Selbsterwärmung, die in dieser Arbeit im Kontext organischen Halbleiter diskutiert wird. Die große Aktivierungsenergie der Leitfähigkeit führt zu S-förmigen Strom-Spannungs-Kennlinien und hat thermisches Umschalten sowie negative differentielle Widerstände zur Folge, was für verschiedene Bauelemente demonstriert wird. Ein detailliertes Verständnis dieser Prozesse ist wichtig, um Beschränkungen für Anwendungen zu erkennen und um entsprechende Verbesserungen einzuführen.:CONTENTS Publications, patents and conference contributions 9 1 Introduction 13 2 Theory 19 2.1 From small molecules to conducting thin films . . . . . . . . . . . . . . . . . . . . 19 2.1.1 Aromatic hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.1.2 Solid state physics of molecular materials . . . . . . . . . . . . . . . . . . . 24 2.1.3 Energetic landscape of an organic semiconductor . . . . . . . . . . . . . . 26 2.1.4 Charge transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2.2 Semiconductor structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.2.1 Semiconductor statistics and transport . . . . . . . . . . . . . . . . . . . . 42 2.2.2 Charge injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 2.2.3 Limitations of the current . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 2.2.4 Metal-oxide-semiconductor structures . . . . . . . . . . . . . . . . . . . . . 57 2.3 Self-heating theory of thermistor device . . . . . . . . . . . . . . . . . . . . . . . . 61 3 Organic transistors 65 3.1 The organic field-effect transistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.1.1 Basic principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.1.2 Device characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 3.1.3 Device geometries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 3.1.4 Device parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 3.1.5 Issues of OFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.1.6 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 3.2 Overview over vertical organic transistors . . . . . . . . . . . . . . . . . . . . . . . 76 3.2.1 VOTs with an unstructured base electrode . . . . . . . . . . . . . . . . . . . 76 3.2.2 VOTs with structured base electrode . . . . . . . . . . . . . . . . . . . . . . 79 3.2.3 Charge injection modulating transistors . . . . . . . . . . . . . . . . . . . . 82 3.2.4 Vertical organic field-effect transistor . . . . . . . . . . . . . . . . . . . . . . 85 3.2.5 Development of the scientific output . . . . . . . . . . . . . . . . . . . . . . 87 3.2.6 Competing technologies and approaches . . . . . . . . . . . . . . . . . . . 88 3.3 Vertical Organic Triodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.1 Stucture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.2 Electronic configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.3.3 Energetic alignment of the diodes . . . . . . . . . . . . . . . . . . . . . . . 92 3.3.4 Current flow in the on and the off-state . . . . . . . . . . . . . . . . . . . . 94 3.3.5 Definition and extraction of parameters . . . . . . . . . . . . . . . . . . . . 95 4 Experimental 101 4.1 General processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.1.1 Thermal vapor deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 4.1.2 Processing tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 4.1.3 Processing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 4.2 Mask setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 4.3 Measurement setups and tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.3.1 Current-voltage measurements . . . . . . . . . . . . . . . . . . . . . . . . . 108 4.3.2 Frequency-dependent measurements . . . . . . . . . . . . . . . . . . . . . 108 4.3.3 Impedance Spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 4.3.4 Ultraviolet and X-ray Photoelectron Spectroscopy . . . . . . . . . . . . . . . 110 4.3.5 Thermal imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 4.4 Materials used in C60 triodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.4.1 Buckminsterfullerene C60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 4.4.2 Tungsten paddlewheel W2(hpp)4 . . . . . . . . . . . . . . . . . . . . . . . . 116 4.4.3 Aluminum and its oxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 4.4.4 Spiro-TTB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 4.5 Materials used in Organic Light-emitting Diodes . . . . . . . . . . . . . . . . . . . 121 5 Introduction of C60 VOTs 123 5.1 Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 5.2 Diode characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 5.3 Base sweep measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 5.4 Determination of parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 5.5 Common-base connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 5.6 Output characteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136 5.7 Frequency-dependent measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 137 5.8 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 6 Effect of annealing 141 6.1 Charge carrier transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 6.2 Sheet resistance and transmittance of the base electrode . . . . . . . . . . . . . . 142 6.3 Investigation of morphological changes . . . . . . . . . . . . . . . . . . . . . . . . 144 6.4 Photoelectron spectroscopy of the base electrode . . . . . . . . . . . . . . . . . . 153 6.5 Influence of air exposure and annealing onto the dopants . . . . . . . . . . . . . . 159 6.6 Electrical characteristics of the diodes . . . . . . . . . . . . . . . . . . . . . . . . . 162 6.7 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 7 Working Mechanism 167 7.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 7.2 Diode characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 7.3 Simulation and modeling of the diode characteristics . . . . . . . . . . . . . . . . . 173 7.4 Interpretation of the operation mechanism . . . . . . . . . . . . . . . . . . . . . . . 181 7.5 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 8 Optimization of VOTs 183 8.1 Misalignment of the electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 8.2 Use of doping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 8.3 Variation of the intrinsic layer thickness . . . . . . . . . . . . . . . . . . . . . . . . . 190 8.4 Structuring the active area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 8.5 High-frequency operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 8.6 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207 9 Self-heating in organic semiconductors 209 9.1 Temperature activation in C60 triodes . . . . . . . . . . . . . . . . . . . . . . . . . . 210 9.2 nin-C60 crossbar structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 9.3 Thermal switching in organic semiconductors . . . . . . . . . . . . . . . . . . . . . 216 9.4 Self-heating in large area devices: Organic LEDs . . . . . . . . . . . . . . . . . . . 218 9.5 Intermediate summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 10 Conclusion and Outlook 227 10.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 10.2 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 A Appendix 233 A.1 Appendix 1: Accuracy of the current gain . . . . . . . . . . . . . . . . . . . . . . . 233 A.2 Appendix 2: Fit of XRR measurements . . . . . . . . . . . . . . . . . . . . . . . . . 234 A.3 Appendix 3: Atomic force microscopy . . . . . . . . . . . . .

Cumulative index to NASA Tech Briefs, 1963-1967

Cumulative index to NASA survey on technology utilization of aerospace research outpu

NASA Tech Briefs, Winter 1978

Topics covered include: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of selected innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14

Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

NASA Tech Briefs, July 1990

Topics include: New Product Ideas; NASA TU Services; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Nanofabrication

We face many challenges in the 21st century, such as sustainably meeting the world's growing demand for energy and consumer goods. I believe that new developments in science and technology will help solve many of these problems. Nanofabrication is one of the keys to the development of novel materials, devices and systems. Precise control of nanomaterials, nanostructures, nanodevices and their performances is essential for future innovations in technology. The book "Nanofabrication" provides the latest research developments in nanofabrication of organic and inorganic materials, biomaterials and hybrid materials. I hope that "Nanofabrication" will contribute to creating a brighter future for the next generation

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented