The Bakerian Lecture, 1988 - Amorphous semiconductors: a new generation of electronic materials

1988 ◽  
Vol 420 (1859) ◽  
pp. 201-218 ◽  
Keyword(s):  
Thin Film ◽  
Electronic Properties ◽  
Carrier Transport ◽  
Field Effect Transistors ◽  
Consumer Products ◽  
Amorphous Semiconductors ◽  
Film Material ◽  
Large Area ◽  
Wide Range ◽  
New Generation

The review deals with the electronic properties and recent applications of amorphous silicon (a-Si), which can be regarded as the first member of a new generation of electronically viable thin-film materials. After a brief introduction to the structure and the distribution of electronic states in a-Si the preparation of the material by the decomposition of silane in a radio-frequency glow discharge is discussed. The presence of hydrogen in the deposition process is of crucial importance; saturation of defect states, particularly of dangling bonds in the growing structure, leads to a material with a remarkably low density of gap states. Effective substitutional doping from the gas phase now becomes possible with wide-ranging control of the electronic properties. A brief discussion of the doping mechanism in amorphous solids is followed by a summary of carrier transport mechanisms in a-Si, investigated by fast transient techniques. The possibility of doping in a-Si has removed a major limitation in the a-semiconductor field and has, during the past 10 years, led to an upsurge in applied interest in this electronically controllable thin film material. A summary of the present state of applied developments, many already in industrial production, is given. Two groups are discussed in some detail. The first, the photovoltaic development, is based on the a-Si p–i–n junction, and forms part of a wide range of consumer products, but larger area photovoltaic panels are now in production. In the second major development a-Si field effect transistors are used as the addressable elements in large area liquid crystal displays. Remarkable progress has been made with thin film colour displays for small portable television sets. The use of a-Si elements in addressable linear image sensing arrays for telefax applications, coupled with a-Si high-voltage transistor arrays in the associated printers, represents an important step towards an integrated a-Si technology in large-area applications.

Improved Mobility and Bias Stability of Thin Film Transistors Using the Double-Layer a-InGaZnO/a-InGaZnO:N Channel

2016 ◽  
Vol 16 (4) ◽  
pp. 3659-3663
Author(s):  
H Yu ◽  
L Zhang ◽  
X. H Li ◽  
H. Y Xu ◽  
Y. C Liu
Keyword(s):  
Thin Film ◽  
Double Layer ◽  
Thin Film Transistors ◽  
Carrier Transport ◽  
Single Layer ◽  
Channel Structure ◽  
Gate Insulator ◽  
Large Area ◽  
Threshold Voltage Shift ◽  
High Carrier

The amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) were demonstrated based on a double-layer channel structure, where the channel is composed of an ultrathin nitrogenated a-IGZO (a-IGZO:N) layer and an undoped a-IGZO layer. The double-layer channel device showed higher saturation mobility and lower threshold-voltage shift (5.74 cm2/Vs, 2.6 V) compared to its single-layer counterpart (0.17 cm2/Vs, 7.23 V). The improvement can be attributed to three aspects: (1) improved carrier transport properties of the channel by the a-IGZO:N layer with high carrier mobility and the a-IGZO layer with high carrier concentration, (2) reduced interfacial trap density between the active channel and the gate insulator, and (3) higher surface flatness of the double-layer channel. Our study reveals key insights into double-layer channel, involving selecting more suitable electrical property for back-channel layer and more suitable interface modification for active layer. Meanwhile, room temperature fabrication amorphous TFTs offer certain advantages on better flexibility and higher uniformity over a large area.

A One-Micrometer Channel Length α-Si Thin-Film Field-Effect Transistor

1984 ◽  
Vol 33 ◽  
Author(s):  
Z. Yaniv ◽  
G. Hansell ◽  
M. Vijan ◽  
V. Cannella
Keyword(s):  
Thin Film ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Liquid Crystal Displays ◽  
Channel Length ◽  
Large Area ◽  
Short Channel ◽  
Threshold Voltages ◽  
Effect Transistor ◽  
Si Thin Film

ABSTRACTA new method of fabricating short channel α-Si TFTs has been developed. One-micrometer channel length α-Si thin-film field effect transistors have been fabricated and tested. Threshold voltages as low as 1.9V and field-effect mobilities as high as 1 cm 2/V-sec are reported. These devices were fabricated by techniques compatible with the production of large area liquid crystal displays.

Amorphous Semiconductors Studied by First-principles Simulations: Structure and Electronic Properties

2009 ◽  
Vol 1153 ◽  
Author(s):  
Karol Jarolimek ◽  
Robert A. de Groot ◽  
Gilles A. de Wijs ◽  
Miro Zeman
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Large Cell ◽  
Band Gap Energy ◽  
Amorphous Semiconductors ◽  
Structural Defects ◽  
Defect States ◽  
Wide Range

AbstractAtomistic models of amorphous solids enable us to study properties that are difficult to address with experimental methods. We present a study of two amorphous semiconductors with a great technological importance, namely a- Si:H and a-SiN:H. We use first-principles density functional theory (DFT), i.e. the interatomic forces are derived from basic quantum mechanics, as only that provides accurate interactions between the atoms for a wide range of chemical environments (e.g. brought about by composition changes). This type of precision is necessary for obtaining the correct short range order. Our amorphous samples are prepared by a cooling from liquid approach. As DFT calculations are very demanding, typically only short simulations can be carried out. Therefore most studies suffer from a substantial amount of defects, making them less useful for modeling purposes. We varied the cooling rate during the thermalization process and found it has a considerable impact on the quality of the resulting structure. A rate of 0.02 K/fs proves to be sufficient to prepare realistic samples with low defect concentrations. To our knowledge these are the first calculations that are entirely based on first-principles and at the same time are able to produce defect-free samples. Because of the high computational load also the size of the systems has to remain modest. The samples of a-Si:H and a-SiN:H contain 72 and 110 atoms, respectively. To examine the convergence with cells size, we utilize a large cell of a-Si:H with a total of 243 atoms. As we obtain essentially the same structure as with the smaller sample, we conclude that the use of smaller cells is justified. Although creating structures without any defects is important, on the other hand a small number of defects can give valuable information about the structure and electronic properties of defects in a-Si:H and a-SiN:H. In our samples we observe the presence of both the dangling bond (undercoordinated atom) and the floating bond (over-coordinated atom). We relate structural defects to electronic defect states within the band gap. In a-SiN:H the silicon-silicon bonds induce states at the valence and conduction band edges, thus decreasing the band gap energy. This finding is in agreement with measurements of the optical band gap, where increasing the nitrogen content increases the band gap.

Organic thin-film transistors of phthalocyanines

2008 ◽  
Vol 80 (11) ◽  
pp. 2231-2240 ◽  
Author(s):  
Liqiang Li ◽  
Qingxin Tang ◽  
Hongxiang Li ◽  
Wenping Hu ◽  
Xiaodi Yang ◽  
...  
Keyword(s):  
Thin Film ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Crystal Packing ◽  
Organic Thin Film Transistors ◽  
Semiconductor Materials ◽  
Organic Thin Film ◽  
Future Prospects ◽  
Large Area ◽  
Packing Structure

Organic thin-film field-effect transistors (OTFTs) are emerging as attractive candidates for low-price, large-area, and flexible circuit applications. A variety of organic compounds have been utilized as active semiconductor materials for OTFTs, among which phthalocyanine compounds have attracted considerable attention owing to their remarkable chemical and thermal stability as well as good field-effect performance. Here, we review recent results on the phthalocyanine-based OTFTs. The correlation between the crystal packing structure and the charge transport property is discussed, and we conclude with a description of the future prospects for phthalocyanine-based OTFTs.

Effects of Microwave and Furnace Annealing for P-Type SnO Thin Film Material in Oxygen Ambient

2021 ◽  
Vol 21 (9) ◽  
pp. 4763-4767
Author(s):  
Yu-Xin Zhang ◽  
Chien-Hung Wu ◽  
Li-Wei Yeh ◽  
Yi-Ming Chen ◽  
Kow-Ming Chang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Performance ◽  
Transparent Conductive Oxide ◽  
Film Material ◽  
High Electron ◽  
Flat Panel Display ◽  
Furnace Annealing ◽  
Wide Range ◽  
C 30

Transparent conductive oxide (TCO) semiconductors are attracted considerable attention due to a wide range of applications, such as flat panel display (FPD), touch panels, solar cells, and other optoelectronic devices. Owing to the different carrier conduction paths between n-type and P-type TCOs, the n-type TCO used in TFTs usually have high Ion/Ioff current ratio (>107) and high electron mobility (>10 cm2/V·s), P-type TCO TFTs are both lower than that of n-type one. For complementary circuits design and applications, however, both P-type and n-type semiconductor materials are equally important. For SnO thin films, it is important to adjust the ratio of Sn2+ (SnO P-type) and Sn4+ (SnO2 n-type) in order to modulate the electrical characteristics. In this investigation of post treatment for SnO thin films, both microwave annealing (MWA) and furnace annealing process with 02 ambient are studied. The results show that SnO thin films are optimized at 300 °C, 30 minutes furnace annealing, the P-type SnO/SnO2 thin film shows surface mean roughness 0.168 nm, [Sn2+]/[Sn4+] ratio as 0.838, at least 80% transmittance between 380 nm-700 nm visible light. Withthe results, SnO can be even used to fabricate high performance P-type thin film transistors (TFTs) device for future applications.

Organic Materials for Large Area Electronics

2008 ◽  
Vol 608 ◽  
pp. 159-179 ◽  
Author(s):  
Richard Friend
Keyword(s):  
Thin Films ◽  
Field Effect ◽  
Organic Materials ◽  
Field Effect Transistors ◽  
Semiconductor Devices ◽  
Large Area ◽  
Active Matrix ◽  
Semiconductor Physics ◽  
Light Emitting ◽  
Wide Range

Organic materials have been developed to operate as the active semiconductor in a wide range of semiconductor devices, including light-emitting diodes, LEDs, field-effect transistors, FETs, and photovoltaic diodes, PVs. The ability to process these materials as thin films over large areas makes possible a range of applications, currently in displays, as LEDs and as active matrix FET arrays, and solar cells. This article reviews developments in semiconductor physics of these materials and in their application in semiconductor devices

scholarly journals Conformally Gated Surface Conducting Behaviors of Single-Walled Carbon Nanotube Thin-Film-Transistors

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3361
Author(s):  
Kyung-Tae Kim ◽  
Keon Woo Lee ◽  
Sanghee Moon ◽  
Joon Bee Park ◽  
Chan-Yong Park ◽  
...  
Keyword(s):  
Field Effect ◽  
Carrier Transport ◽  
Field Effect Transistors ◽  
Low Cost ◽  
Cost Effective ◽  
Electrical Performance ◽  
Solution Synthesis ◽  
Large Area ◽  
Element Analysis ◽  
Single Walled Carbon

Semiconducting single-walled carbon nanotubes (s-SWCNTs) have gathered significant interest in various emerging electronics due to their outstanding electrical and mechanical properties. Although large-area and low-cost fabrication of s-SWCNT field effect transistors (FETs) can be easily achieved via solution processing, the electrical performance of the solution-based s-SWCNT FETs is often limited by the charge transport in the s-SWCNT networks and interface between the s-SWCNT and the dielectrics depending on both s-SWCNT solution synthesis and device architecture. Here, we investigate the surface and interfacial electro-chemical behaviors of s-SWCNTs. In addition, we propose a cost-effective and straightforward process capable of minimizing polymers bound to s-SWCNT surfaces acting as an interfering element for the charge carrier transport via a heat-assisted purification (HAP). With the HAP treated s-SWCNTs, we introduced conformal dielectric configuration for s-SWCNT FETs, which are explored by a carefully designed wide array of electrical and chemical characterizations with finite-element analysis (FEA) computer simulation. For more favorable gate-field-induced surface and interfacial behaviors of s-SWCNT, we implemented conformally gated highly capacitive s-SWCNT FETs with ion-gel dielectrics, demonstrating field-effect mobility of ~8.19 cm2/V⋅s and on/off current ratio of ~105 along with negligible hysteresis.

Thin Film Diamond Field Effect Transistors For High Power Applications

1997 ◽  
Vol 483 ◽  
Author(s):  
Hui Jin Looi ◽  
Lisa Ys Pang ◽  
Richard B. Jackman
Keyword(s):  
Thin Film ◽  
High Power ◽  
Field Effect ◽  
High Performance ◽  
Field Effect Transistors ◽  
Schottky Diodes ◽  
Film Material ◽  
Near Surface ◽  
Suitable Material ◽  
P Type

AbstractEarly predictions that diamond would be a suitable material for high performance, high power devices were not supported by the characteristics of diodes and field effect transistors (FETs) fabricated on boron doped (p-type) thin film material. In this paper commercially accessible polycrystalline thin film diamond has been turned p-type by the incorporation of near surface hydrogen. Schottky diodes and metal-semiconductor FETs (MESFETs) have been fabricated using this approach which display unprecedented performance levels; diodes with a rectification ratio > 106, leakage currents < l nA, no indication of reverse bias breakdown at 100V and an ideality factor of 1.1 have been made. Simple MESFET structures that are capable of withstanding VDS values of 100V with low leakage and current saturation (pinch-off) characteristics have also been fabricated. Predictions based upon experiments performed on these devices suggest that optimised device structures will be capable of operation at power levels up to 20 W/mm, implying that thin film diamond may after all be an interesting material for power applications.

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