共查询到20条相似文献,搜索用时 15 毫秒
1.
Qiong Qi 《Applied Surface Science》2009,255(9):5096-5099
Pentacene thin-film transistors (TFTs) were fabricated on thermally grown SiO2 gate insulator under the conditions of various pre-cleaning treatments. Initial nucleation and growth of the material films on treated substrates were observed by atomic force microscope. The performance of fabricated TFT devices with different surface cleaning approaches was found to be highly related to the initial film morphologies. In contrast to the three-dimensional island-like growth mode on SiO2 under an organic cleaning process, a layer-by-layer initial growth occurred on the SiO2 insulator cleaned with ammonia solution, which was believed to be the origination of the excellent electrical properties of the TFT device. Field effect mobility of the TFT device could achieve as high as 1.0 cm2/Vs on the bared SiO2/Si substrate and the on/off ratio was over 106. 相似文献
2.
Y.R. Liu Author Vitae J.B. Peng Author Vitae P.T. Lai Author Vitae 《Applied Surface Science》2007,253(17):6987-6991
Polymer thin-film transistors (PTFTs) based on poly(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) semiconductor are fabricated by spin-coating process and characterized. In the experiments, solution preparation, deposition and device measurements are all performed in air for large-area applications. Hysteresis effect and gate-bias stress effect are observed for the devices at room temperature. The saturation current decreases and the threshold voltage shifts toward the negative direction upon gate-bias stress, but carrier mobility hardly changes. By using quasi-static C-V analysis for MOS capacitor structure, it can be deduced that the origin of threshold-voltage shift upon negative gate-bias stress is predominantly associated with hole trapping within the SiO2 gate dielectric near the SiO2/MEH-PPV interface due to hot-carrier emission. 相似文献
3.
Ute Zschieschang R. Thomas Weitz Klaus Kern Hagen Klauk 《Applied Physics A: Materials Science & Processing》2009,95(1):139-145
The bias stress effect in pentacene organic thin-film transistors has been investigated. The transistors utilize a thin gate
dielectric based on an organic self-assembled monolayer and thus can be operated at low voltages. The bias stress-induced
threshold voltage shift has been analyzed for different drain-source voltages. By fitting the time-dependent threshold voltage
shift to a stretched exponential function, both the maximum (equilibrium) threshold voltage shift and the time constant of
the threshold voltage shift were determined for each drain-source voltage. It was found that both the equilibrium threshold
voltage shift and the time constant decrease significantly with increasing drain-source voltage. This suggests that when a
drain-source voltage is applied to the transistor during gate bias stress, the tilting of the HOMO and LUMO bands along the
channel creates a pathway for the fast release of trapped carriers. 相似文献
4.
Jun Li Fan ZhouHua-Ping Lin Xue-Yin JiangWen-Qing Zhu Zhi-Lin Zhang 《Superlattices and Microstructures》2011,50(2):191-197
We demonstrated the tunable contact resistance in pentacene thin film transistor (TFT) by inserting an organic-inorganic hybrid interlayer between Au electrode and pentacene layer. The contact resistance of pentacene-TFT varies with concentration of pentacene-TFT varies with concentration of MoOx in organic-inorganic hybrid interlayer. MoOx in organic-inorganic hybrid interlayer. The contact resistance of the device with 55 wt% MoOx doped pentacene interlayer is about 7.8 times smaller than that of device without interlayer at the gate voltage of −20 V. Comparing the properties of pentacene-TFT without interlayer, the performance of the pentacene-TFT with 55 wt% MoOx doped pentacene was significantly improved: saturation mobility increased from 0.39 to 0.87 cm2/V s, threshold voltage reduced from −21.3 to −7.2 V, and threshold swing varied from 3.75 to 1.39 V/dec. Our results indicated that the organic-inorganic hybrid interlayer is an effective way to improve the performance of p-channel OTFTs. 相似文献
5.
Shuhei Tatemichi Musubu Ichikawa Shimpei Kato Toshiki Koyama Yoshio Taniguchi 《固体物理学:研究快报》2008,2(2):47-49
The authors describe an organic complementary inverter with N,N′‐ditridecyl‐3,4,9,10‐perylenetetracarboxylic diimide as an n‐type semiconductor and pentacene as a p‐type semiconductor. Each transistor of the inverter exhibited high carrier mobility: 1.62 cm2/Vs for an n‐type drive transistor and 0.57 cm2/Vs for a p‐type switch transistor. The gain of the inverter reached 125. Another inverter using Ta2O5 as a high κ gate dielectric performed well with a gain of 500 and an operation voltage of only 5 V.
6.
A reliable surface treatment for the pentacene/gate dielectric interface was developed to enhance the electrical transport properties of organic thin-film transistors (OTFTs). Plasma-polymerized fluorocarbon (CFx) film was deposited onto the SiO2 gate dielectric prior to pentacene deposition, resulting in a dramatic increase of the field-effect mobility from 0.015 cm2/(V s) to 0.22 cm2/(V s), and a threshold voltage reduction from −14.0 V to −9.9 V. The observed carrier mobility increase by a factor of 10 in the resulting OTFTs is associated with various growth behaviors of polycrystalline pentacene thin films on different substrates, where a pronounced morphological change occurs in the first few molecular layers but the similar morphologies in the upper layers. The accompanying threshold voltage variation suggests that hole accumulation in the conduction channel-induced weak charge transfer between pentacene and CFx. 相似文献
7.
M.?Fiebig C.?Erlen M.?G?llner P.?Lugli B.?Nickel 《Applied Physics A: Materials Science & Processing》2009,95(1):113-117
A confocal setup with a spatial resolution in the submicron regime is employed for investigating the response of pentacene
transistors to local illumination. The transistors show enhanced and inhomogeneous photoresponse in the proximity of the hole-injecting
contact. These inhomogeneities represent contact areas of varying injection efficiency. Thus, this technique allows imaging
of contact efficiencies with submicron resolution over large areas up to hundreds of microns. Drift–diffusion simulations
including a photogeneration/recombination process have been performed to model the photoresponse. The simulations illustrate
that the potential drop along the channel is dramatically reduced in the illuminated area due to photoconductance (i.e. photoinjection
of excitons and subsequent dissociation). Also, the injection barrier for holes is reduced if the illumination is close to
the hole-injecting electrode. The rapid decay of the photoresponse with increasing distance to the positively biased electrode
is caused by the limited electron mean free path in our devices. 相似文献
8.
Pasquale D’Angelo Pablo Stoliar Tobias Cramer Antonio Cassinese Francesco Zerbetto Fabio Biscarini 《Applied Physics A: Materials Science & Processing》2009,95(1):55-60
A dynamic method for quantifying the amount and mechanism of trapping in organic field effect transistors (OFETs) is proposed.
It exploits transfer characteristics acquired upon application of a triangular waveform gate sweep V
G. The analysis of the transfer characteristics at the turning point V
G=−V
max between forward and backward gate sweeps, viz. around the maximum gate voltage V
max applied, provides a differential slope Δm which depends exclusively on trapping. Upon a systematic change of V
max it is possible to extract the initial threshold voltage, equivalent to one of the observables of conventional stress measurements,
and assess the mechanism of trapping via the functional dependence on the current. The analysis of the differential logarithmic
derivative at the turning point yields the parameters of trapping, as the exponent β and the time scale of trapping τ. In the case of an ultra-thin pentacene OFET we extract β=1 and τ=102–103 s, in agreement with an exponential distribution of traps. The analysis of the hysteresis parameter Δm is completely general and explores time scales much shorter than those involved in bias stress measurements, thus avoiding
irreversible damage to the device. 相似文献
9.
T. Mills L. G. Kaake X.-Y. Zhu 《Applied Physics A: Materials Science & Processing》2009,95(1):291-296
Electrolytes are finding applications as dielectric materials in low-voltage organic thin-film transistors (OTFT). The presence
of mobile ions in these materials (polymer electrolytes or ion gels) gives rise to very high capacitance (>10 μF/cm2) and thus low transistor turn-on voltage. In order to establish fundamental limits in switching speeds of electrolyte gated
OFETs, we carry out in situ optical spectroscopy measurement of a poly(3-hexylthiophene) (P3HT) OTFT gated with a LiClO4:poly(ethyleneoxide) (PEO) dielectric. Based on spectroscopic signatures of molecular vibrations and polaron transitions,
we quantitatively determine charge carrier concentration and diffusion constants. We find two distinctively different regions:
at V
G≥−1.5 V, drift-diffusion (parallel to the semiconductor/dielectric interface) of hole-polarons in P3HT controls charging of
the device; at V
G<−1.5 V, electrochemical doping of the entire P3HT film occurs and charging is controlled by drift/diffusion (perpendicular
to the interface) of ClO4
− counter ions into the polymer semiconductor. 相似文献
10.
Harald Etschmaier Peter Pacher Alexandra Lex Gregor Trimmel Christian Slugovc Egbert Zojer 《Applied Physics A: Materials Science & Processing》2009,95(1):43-48
For the design and manufacture of complex integrated circuits, control over the threshold voltage of the transistors is essential.
In the present contribution, we present a non-invasive method to tune the threshold voltage of organic thin-film transistors
after device assembly over a wide range without any significant degradation of the device characteristics. This is realized
by incorporating a thin, chemically reactive siloxane layer bonded to the gate oxide. This results in threshold voltages of
around 70 V in the as-prepared devices. By exposing a transistor modified in this way to ammonia at different concentrations,
the threshold voltage can be tuned in steps of only a few volts. This treatment affects only the charge density at the semiconductor–dielectric
interface, leaving the overall shape of the transistor characteristics and the charge-carrier mobility largely unaltered. 相似文献
11.
Electrical Characteristics of Copper Phthalocyanine Thin-Film Transistors with Polyamide-6/Polytetrafluoroethylene Gate Insulator 下载免费PDF全文
Polyamide-6(PA 6)/polytetrafluoroethylene is studied as a potential gate dielectric for flexible organic thin film transistors. The same method used for the formation of organic semiconductor and gate dielectric films greatly simplifies the fabrication process of devices. The fabricated transistors show good electrical characteristics. Ambipolar behaviour is observed even when the device is operated in air. 相似文献
12.
Organic field-effect transistors were fabricated with vapor-grown rubrene single crystals in a staggered top-contact configuration.
The devices were electrically characterized by measuring the transfer curves at low drain voltage. In parallel to these measurements,
a model is developed to account for the subthreshold regime of the transistors. The model is based on the multiple trapping
and thermal release concept, which assumes that charge transport is limited by a single level of shallow traps located close
to the transport band edge. It is shown that the threshold voltage no longer establishes at the transition between the depletion
and accumulation regimes. Instead, the threshold corresponds to the point at which traps are filled. This results in a subthreshold
current that varies linearly with gate voltage. Moreover, the subthreshold current at low drain voltages increases with drain
voltage. These finding are in good agreement with the experimental data. 相似文献
13.
Thermal Stability of Reliable Polycrystalline Zirconium Oxide for Nonvolatile Memory Application 下载免费PDF全文
Thermal stability of resistive switching of stoichiometric zirconium oxide thin films is investigated for high yielding nonvolatile memory application. The A1/ZrO2/AI cell fabricated in the conventional device process shows highly reliable switching behaviour between two distinct stable resistance states. The retention capabilities are also tested under various conditions and temperatures. The excellent performance of Ai/ZrO2/AI ceil can be explained by assuming that anode/ZrO2 interface exists and by conducting filament forming/rupture mechanism. The device failure is illustrated in terms of permanent conducting filaments formation. 相似文献
14.
Polarity-Free Resistive Switching Characteristics of CuxO Films for Non-volatile Memory Applications 下载免费PDF全文
Resistive switching characteristics of CuxO films grown by plasma oxidation process at room temperature are investigated. Both bipolar and unipolar stable resistive switching behaviours are observed and confirmed by repeated current voltage measurements. It is found that the RESET current is dependent on SET compliance current. The mechanism behind this new phenomenon can be understood in terms of conductive filaments formation/rupture with the contribution of Joule heating. 相似文献
15.
Musubu Ichikawa Nobuyasu Hiramatsu Norimasa Yokoyama Tetsuzo Miki Susumu Narita Toshiki Koyama Yoshio Taniguchi 《固体物理学:研究快报》2007,1(1):R37-R39
We demonstrate that a bipyridyl substituted oxadiazole (Bpy‐OXD) shows high electron mobility that reached above 10–3 cm2/Vs. We believe that the high mobility results from both the hybrid molecular structure of the two electron‐accepting units: bipyridyl and oxadiazole, and the planar molecular structure based on its lack of sterically hindered bulky substituent. The computational analysis elucidates that the amorphous nature of Bpy‐OXD in thin‐film state probably results from the polymorphic effect in isolated state and the volume effect in solid state. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
16.
Thin films of 4-tricyanovinyl-N,N-diethylaniline (TCVA) with different thickness were prepared using thermal evaporation technique. A relative permittivity, ?r, of 3.04 was estimated from the dependence of capacitance on film thickness. The current density-voltage (J-V) characteristics of TCVA thin films have been investigated at different temperatures. At low-voltage region, the current conduction in the Au/TCVA/Au sandwich structures obeys Ohm's law. At the higher-voltage regions, the charge transport phenomenon appears to be space-charge-limited current (SCLC) dominated by an exponential distribution of traps with total trap concentration of 1.21 × 1022 m−3. In addition, various electrical parameters were determined. 相似文献
17.
In this letter the stability of transparent thin‐film transistors (TTFTs) based on the ZnO–SnO2 (ZTO) material system is investigated. Bottom‐gate devices have been subject to electrical stress via a gate–source bias of 10 V and a drain‐source bias of 10 V leading to a drain–source current of 188 µA. In optimized TTFTs with a composition of [Zn]:[Sn] = 36:64 the relative change of the saturated field effect mobility was less than 1% and the threshold voltage shift was about 320 mV after 1000 hours of operation. This extraordinary stability of ZTO TTFTs underlines their suitability as drivers in active matrix OLED displays. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
18.
The metal oxide nanometer film semiconductor field-effect transistor (MONSFET) is reported. In this device, a combination of undoped semiconductor and nanometer film serves as the active layer. When a negative gate-source voltage is applied, electrons from the nanometer film enter into the semiconductor layer to form the conducting channel, and the drain current increases without saturation. This structure makes more materials available for the active layer, and thus suggests a new route to enrich the applications as well as to enhance the performances. 相似文献
19.
We investigated the morphological, structural and electronic properties of Pentacene thin films grown by vacuum thermal evaporation on different inert substrates at room temperature. The results of our AFM and STM analysis give an interplanar spacing of 1.54 nm corresponding to the (0 0 1) distance of the so-called “thin film phase”. The STS measurements show an HOMO-LUMO gap of 2.2 eV. 相似文献
20.
Lei Ai Guojia Fang Longyan Yuan Mingjun Wang Qilin Zhang Xingzhong Zhao 《Applied Surface Science》2008,254(8):2401-2405
Nickel oxide thin films were deposited on fused silica and Si(1 0 0) substrates at different substrate temperatures ranging from room temperature to 400 °C using radio frequency reactive magnetron sputtering from a Ni metal target in a mixture of O2 and Ar. With the increase of substrate temperature, nickel oxide films deposited on the Si substrates exhibit transition from amorphous to poly-crystalline structures with different preferred orientations of NiO(2 0 0) and (1 1 1). The films deposited at higher temperature exhibit higher Ni2+/Ni3+ ratio. With substrate temperature increasing from room temperature to 400 °C, the electrical resistivities of nickel oxide films increase from (2.8 ± 0.1) × 10−2 to (8.7 ± 0.1) Ω cm, and the optical band-gap energies increase from 3.65 to 3.88 eV. A p-nickel oxide/n-zinc oxide heterojunction was fabricated to confirm the p-type conduction of nickel oxide thin film, which exhibited a steadily rectifying behavior. 相似文献