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1.
Bottom-gate transparent IGZO–TFT had been successfully fabricated at relatively low temperature (200 °C). The devices annealing for 4 h at 200 °C exhibit good electrical properties with saturation mobility of 8.2 cm2V?1s?1, subthreshold swing of 1.0 V/dec and on/off current ratio of 5×106. The results revealed that the stability of TFT devices can be improved remarkably by post-annealing treatment. After applying positive gate bias stress of 20 V for 5000 s, the device annealing for 1 h shows a larger positive Vth shift of 4.7 V. However, the device annealing for 4 h exhibits a much smaller Vth shift of 0.04 V and more stable.  相似文献   

2.
The nonvolatile memory thin-film transistors (M-TFTs) using a solution-processed indium-zinc-titanium oxide (IZTiO) active channel and a poly(vinylidene fluoride-trifluoroethylene) ferroelectric gate insulator were fabricated and characterized to elucidate the relationships between the IZTiO channel composition and the memory performances such as program speed and data retention. The compositions of the spin-coated IZTiO layers were modified with different Ti amounts of 0, 2, 5, and 10 mol%. The carrier concentration of IZTiO channel layer was effectively modulated by the incorporated Ti amounts and the defect densities within the channel were effectively reduced by Ti incorporation. The M-TFT fabricated with IZTiO channel with 2-mol% Ti composition exhibited the best overall device performances, in which the μFE, SS, MW, and programmed Ion/off were obtained to be 23.6 cm2 V?1 s?1, 701 mV/decade, 11.8 V, and 1.2 × 105, respectively. Furthermore, thanks to the suitable amounts of Ti incorporation into the IZO, the improved program speed and data retention properties were successfully confirmed.  相似文献   

3.
A novel ligand 9-(4-(4-chlorophenyl)phthalazin-1-yl)-9H-carbazole (HCPC) was designed and prepared, and the corresponding tris-cyclometalated iridium(III) complex Ir(CPC)3 was readily synthesized by the reaction of the ligand with IrCl3 · 3H2O at 80 °C for 20 h. A highly efficient organic light-emitting device using this complex as a dopant was obtained. The device fabricated by solution process showed a maximum luminance of 2948 cd/m2 at a current density of 115.6 mA/cm2 and a maximum external quantum efficiency of 20.2% at 0.18 mA/cm2.  相似文献   

4.
《Solid-state electronics》2006,50(7-8):1355-1358
The electrical properties of Cr/Pt/Au and Ni/Au ohmic contacts with unintentionally doped In2O3 (U-In2O3) film and zinc-doped In2O3 (In2O3:Zn) prepared by reactive magnetron sputtering deposition are described. The lowest specific contact resistance of Cr/Pt/Au and Ni/Au is 2.94 × 10−6 and 1.49 × 10−2 Ω-cm2, respectively, as determined by the transmission line model (TLM) after heat treatment at 300 °C by thermal annealing for 10 min in nitrogen ambient. The indium oxide diodes have an ideality factor of 1.1 and a soft breakdown voltage of 5 V. The reverse leakage current prior to breakdown is around 10−5 A.  相似文献   

5.
A series of simple structures is investigated for realization of the highly efficient green phosphorescent organic light emitting diodes with relatively low voltage operation. All the devices were fabricated with mixed host system by using 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TpPyPB) which were known to be hole and electron type host materials due to their great hole and electron mobilities [μh(TAPC): 1 × 10?2 cm2/V s and μe(TpPyPB): 7.9 × 10?3 cm2/V s] [1]. The optimized device with thin TAPC (5–10 nm) as an anode buffer layer showed relatively high current and power efficiency with low roll-off characteristic up to 10,000 cd/m2. The performances of the devices; with buffer layer were compared to those of simple devices with single layer and three layers. Very interestingly, the double layer device with TAPC buffer layer showed better current and power efficiency behavior compared to that of three layer device with both hole and electron buffer layers (TAPC, TpPyPB, respectively).  相似文献   

6.
Metallization multilayers on the back side of a power device were focused in this study. Si wafers coated with high melting point metals were exposed at 300 °C for 300 h to investigate diffusion condition of the metallization layer. We developed and examined the thermal stability of die bonding material (Au paste) including sub–micrometer–sized Au particles. Auger electron spectroscopy was applied to observe the atomic composition of the multilayers in depth direction after the high temperature aging. Surface morphology was observed using optical microscope and scanning electron microscope. While atomic composition on Ti/Au changed drastically after the high temperature aging, other multilayers maintained their metallization composition. However, the surface morphology was slightly changed on Ti/Ru/Au, W/Au, and Ta/Au. Bond strength on the Ti/Pt/Au kept over 40 MPa with unified bonding layer after exposing at 300 °C for 1000 h.  相似文献   

7.
As an emerging material, graphene has attracted vast interest in solid-state physics, materials science, nanoelectronics and bioscience. Graphene has zero bandgap with its valence and conduction bands are cone-shaped and meet at the K points of the Brillouin zone. Due to its high intrinsic carrier mobility, large saturation velocity, and high on state current density, graphene is also considered as a promising candidate for high-frequency devices. To improve the reliability of graphene FETs, which include shifting the Dirac point voltage toward zero, increasing the channel mobility and decreasing the source/drain contact resistance, we optimized the device fabrication process. For CVD grown graphene, the film transfer and the device fabrication processes may produce interfacial states between graphene and the substrate and make graphene p or n-type, which shift the fermi level far away from the Dirac point. We have found that after graphene film transfer, an annealing process at 400 °C under N2 ambient will shift Dirac point toward zero gate voltage. Ti/Au, Ni, and Ti/Pd/Au source/drain structures have been studied to minimize the contact resistance. According to the measured data, Ti/Pd/Au structure gives the lowest contact resistance (~500 ohm μm). By controlling the process of graphene growth, transfer and device fabrication, we have achieved graphene FETs with a field effective mobility of 16,000 cm2/V s after subtraction of contact resistance. The contact resistivity was estimated in the range of 1.1 × 10?6 Ω cm2 to 8.8 × 10?6 Ω cm2, which is close to state of the art III–V technology. The maximum transconductance was found to be 280 mS/mm at VD = 0.5 V, which is the highest value among CVD graphene FETs published to date.  相似文献   

8.
The electronic properties, morphology and optoelectronic device characteristics of conjugated diblock copolythiophene, poly(3-hexylthiophene)-block -poly(3-phenoxymethylthiophene) (P3HT-b-P3PT), are firstly reported. The polymer properties and structures were explored through different solvent mixtures of chloroform (CHCl3), dichlorobenzene (DCB), and CHCl3:DCB (1:1 ratio). The absorption maximum (λmax) of P3HT-b-P3PT prepared from DCB was around 554 nm with a shoulder peak indicative for the highly crystalline structure around 604 nm while that from CHCl3 was 516 nm without the clear shoulder peak. The field-effect hole mobility of P3HT-b-P3PT increased from ~6.0 × 10?3, ~8.0 × 10?3 to ~2.0 × 10?2 cm2 V?1 s?1 as the DCB content in the solvent mixture enhanced. The AFM images suggested that the highly volatile CHCl3 processing solvent led to the amorphous structure, on the other hand, less volatile DCB resulted in the largely crystalline structure of the P3HT-b-P3PT. Such difference on the polymer structure and hole mobility led to the varied power conversion efficiency (PCE) of the photovoltaic cells fabricated from the blend of P3HT-b-P3PT/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:1, w/w): 1.88 (CHCl3), 2.13 (CHCl3:DCB (1:1)), and 2.60% (DCB). The PCBM blend ratio also significantly affected the surface structure and the solar cell performance. The PCE of polymer/PCBM could be improved to 2.80% while the ratio of polymer to PCBM went to 1:0.7. The present study suggested that the surface structures and optoelectronic device characteristics of conjugated diblock copolymers could be easily manipulated by the processing solvent, the block segment characteristic, and blend composition.  相似文献   

9.
Efficient solution-processed electrophosphorescent devices using two blue-emitting ionic iridium complexes (complex 1 and complex 2) were fabricated, with poly(N-vinylcarbazole) (PVK):1,3-bis(5-(4-tert-butylphenyl)-1,3,4-oxadiazol-2-yl)benzene (OXD-7) as the host and Cs2CO3/Al as the cathode. Using complex 1 as the dopant, we obtained efficient blue-green electrophosphorescence from single-layer devices with a maximum efficiency of 12.2 cd A?1, a maximum brightness of 12,600 cd m?2 and CIE (Commission Internationale de l’Éclairage) coordinates of (0.19, 0.45). And the maximum efficiency of the device based on complex 1 can be further improved to 20.2 cd A?1, when a thin 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBI) layer was inserted between the light-emitting layer and the cathode. Using complex 2 as the dopant, we obtained deep-blue electrophosphorescence with the emission peak at 458 nm and CIE coordinates of (0.16, 0.22). Our work suggests that ionic iridium complexes are promising phosphors for obtaining efficient electrophosphorescence in the blue region.  相似文献   

10.
Bilayered organic field-effect transistors were fabricated by successive vapor-depositions of 1,4-bis{5-[4-(trifluoromethyl)phenyl]thiophene-2-yl}benzene (AC5-CF3) and 5,5″-bis(4-biphenylyl)-2,2′:5′,2″-terthiophene (BP3T). With decreasing thickness of the n-type AC5-CF3 film in contact with the dielectric layer, ambipolar characteristics were improved under both positive and negative gate biases. Two types of asymmetric source/drain electrodes were prepared by either obliquely shadowed lamination or mask-shifted depositions of AlLi and Au. The latter method in which the device was characterized without exposure to air after the electrode deposition of AlLi resulted in remarkable improvement of ambipolarity and reduction of leak currents. Finally, optimized ambipolar mobilities of μe = 5.00 × 10?2 and μh = 1.56 × 10?2 cm2 V?1 s?1) were obtained with 5-nm-thick AC5-CF3 and 30-nm-thick BP3T.  相似文献   

11.
《Applied Superconductivity》1997,5(1-6):139-146
Single crystalline NdBa2Cu3Ox (Nd123) superconductors with dispersed Nd4Ba2Cu2O10 (Nd422) particles were produced by the floating zone partial melting and solidification (FZPMS) method. The initial composition of the precursor material was Nd1.8Ba2.4Cu3.4Ox with or without 0.1 wt% Pt addition. FZPMS was carried out in a low oxygen partial pressure atmosphere. Microstructure of quenched samples were investigated by optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Furthermore, superconductive properties were measured by superconducting quantum interference device (SQUID). The results of SQUID measurements indicate that the critical temperature (Tc) of the samples with Pt addition so produced with the oxygen heat treatment (623 K for 300 h) was 94 K and the critical current density (Jc) was 2.3×104 A/cm2 at 77 K, 0.2 T.  相似文献   

12.
Surface properties of gate insulators strongly affect the device performance of organic thin-film transistors (OTFTs). To improve the performance of OTFTs, we have developed photo-sensitive polyimide gate insulator with fluorine groups. The polyimide gate insulator film could be easily patterned by selective UV exposure without any photoinitiator. The polyimide gate insulator film, fabricated at 130 °C, has a dielectric constant of 2.8 at 10 kHz, and leakage current density of <1.6 × 10?10 A/cm2 while biased from 0 to 90 V. To investigate the potential of the polyimide with fluorine groups as a gate insulator, we fabricated C10-BTBT TFTs. The field-effect mobility and the on/off current ratio of the TFTs were measured to be 0.76 ± 0.09 cm2/V s and >106, respectively.  相似文献   

13.
For the achievement of microactuators based on piezoelectric thin films, a Pt/Ti/Si bottom electrode is widely used. This study presents the experimental results for Ti out-diffusion in Pt and Si for both sputtered Pt/Ti and Pt/TiOx electrodes. These results have been compared before and after a rapid thermal annealing (RTA). The diffusion has been characterized by secondary ion mass spectroscopy (SIMS) analysis using Cs+ as a primary ion source. The Pt orientation has been observed by XRD measurements. Ti thin films (20 nm) have been sputtered in pure Ar whereas TiOx films have been obtained by reactive sputtering in a mixture of Ar/O2 (90/10). Finally, the Pt (100 nm) has been sputtered without vacuum breaking. After RTA (400°C, 30 s, in N2), the Pt film exhibited a (1 1 1) orientation for both Ti and TiOx adhesion films. The roughness of the Pt film measured by AFM with TiOx underlayer was 80% less than that of the Pt/Ti bi-layer. The TiOx film, as shown by SIMS analysis, has drastically reduced the diffusion of Ti in both Pt and Si. This phenomenon is accompanied by a very low Pt roughness. These results are analyzed in terms of diffusion and regrowth mechanisms inside the Pt film.  相似文献   

14.
The flexible organic ferroelectric nonvolatile memory thin film transistors (OFMTs) were fabricated on polydimethylsiloxane (PDMS) elastomer substrates, in which an organic ferroelectric poly(vinylidene-trifluoroethylene) and an organic semiconducting poly(9,9-dioctylfluorene-co-bithiophene) layers were used as gate insulator and active channel, respectively. The carrier mobility, on/off ratio, and subthreshold swing of the OFMTs fabricated on PDMS showed 5 × 10−2 cm2 V−1 s−1, 7.5 × 103, and 2.5 V/decade, respectively. These obtained values did not markedly change when the substrate was bent with a radius of curvature of 0.6 cm. The memory on/off ratio was initially obtained to be 1.5 × 103 and maintained to be 20 even after a lapse of 2000 s. The fabricated OFMTs exhibited sufficiently encouraging device characteristics even on the PDMS elastomer to realize mechanically stretchable nonvolatile memory devices.  相似文献   

15.
AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with 2 MeV protons, carbon, oxygen, iron and krypton ions with fluences ranging from 1 × 109 cm?2 to 1 × 1013 cm?2. DC, pulsed IV characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured before and after irradiation. In parallel, a thick GaN reference layer was also irradiated with the same ions and was characterized by X-ray diffraction, photoluminescence, Hall measurements before and after irradiation. Small changes in the device performance were observed after irradiation with carbon and oxygen at a fluence of 5 × 1010 cm?2. Remarkable changes in device characteristics were seen at a fluence of 1 × 1012 cm?2 for carbon, oxygen, iron and krypton irradiation. Similarly, remarkable changes were also observed in the GaN layer for irradiations with fluence of 1 × 1012 cm?2. The results found on devices and on the GaN layer were compared and correlated.  相似文献   

16.
The study explored titanium dioxide (TiO2) on aluminum gallium arsenide (AlGaAs) prepared by liquid phase deposition (LPD) at 40 °C. The leakage current density was about 8.4 × 10?6 A/cm2 at 1 MV/cm. The interface trap density (Dit) and the flat-band voltage shift (ΔVFB) were 2.3 × 1012 cm?2 eV?1 and 1.2 V, respectively. After rapid thermal annealing (RTA) in the ambient N2 at 350 °C for 1 min, the leakage current density, Dit, and ΔVFB were improved to 2.4 × 10?6 A/cm2 at 1 MV/cm, 7.3 × 1011 cm?2 eV?1, and 1.0 V, respectively. Finally, the study demonstrates the application to the AlGaAs/InGaAs metal–oxide–semiconductor pseudomorphic high-electron-mobility transistor (MOS-PHEMT). The results indicate the potential of the proposed device with a LPD-TiO2 gate oxide for power application.  相似文献   

17.
We have developed photo-sensitive, low-temperature processable, soluble polyimide (PSPI) gate insulator with excellent resistance to the photo-patterning process. The PSPI was synthesized through one-step condensation polymerization of monomers 5-(2,5-dioxytetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 3,5-diaminobenzyl cinnamate (DABC). PSPI thin film, fabricated at 160 °C, has a dielectric constant of 3.3 at 10 kHz, and leakage current density of <1.7 × 10?10 A/cm2, while biased from 0 to 100 V. PSPI could be easily patterned by selective UV-light exposure and dipping into γ-butyrolactone. To investigate the potential of the polyimide as the photo-patternable gate insulator, we fabricated pentacene OTFTs and confirmed the PSPI’s resistance to the photo-patterning process. The photo-patternable polyimide shows promise as gate dielectrics for OTFTs.  相似文献   

18.
We present the first systematic lifetime tests which show excellent long-term reliability for 600 V GaN-on-Si power switches.High voltage accelerated life testing in the OFF-state yields a field related mean-time-to-failure (MTTF) greater than 3 × 108 h for a 600 V operating condition. High temperature accelerated testing in the ON-state gives an MTTF of about 6 × 108h at a 150 °C use condition. High temperature operating life testing using hard switched boost converters at 175 °C shows no measurable device degradation after 3000 h of operation. These results show that the intrinsic reliability of the new device technology is more than adequate for commercial and industrial power electronics applications.  相似文献   

19.
Light-emitting field-effect transistors with a liquid crystalline polymer of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2) were investigated under alternating current (AC) gate operations. Bottom-contact/top-gate devices were fabricated with indium-tin-oxide (ITO) source/drain electrodes, a poly(methyl methacrylate) dielectric and a gold gate electrode. The crystalline F8T2 film exhibited ambipolar characteristics with electron and hole mobilities of 1.8 × 10?3 and 2.5 × 10?3 cm2/V s, respectively, although the threshold voltage was considerably higher for electron injection. By applying square-wave voltages to the gate, light emission was obtained at the both edges of the source and drain electrodes by alternating injection of opposite carriers even when the source and drain were grounded. The light intensity was enhanced in the channel region by biasing the source negative while biasing the drain positive where the holes injected from the drain were transported to recombine with the electrons injected at the source edge.  相似文献   

20.
We have demonstrated a low temperature process for a ferroelectric non-volatile random access memory cell based on a one-transistor–one-capacitor (1T1C) structure for application in flexible electronics. The n-channel thin film transistors (TFTs) and ferroelectric capacitors (FeCaps) are fabricated using cadmium sulfide (CdS) as the semiconductor and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer as the ferroelectric material, respectively. The maximum processing temperature for the TFTs is 100 °C and 120 °C for the FeCaps. The TFT shows excellent access control of the FeCap in the 1T1C memory cell, and the stored polarization signals are undisturbed when the TFT is off. The fabricated 1T1C memory cell was also evaluated in a FRAM circuit. The memory window on the bit line was demonstrated as 2.3 V, based on the 1T1C memory cell with a TFT having dimensions of 80 μm/5 μm (W/L) and a FeCap with an area of 0.2 × 10?3 cm2 using a bit line capacitor of 1 nF pre-charged at 17.2 V. The 1T1C memory cell is fabricated using photolithographic processes, allowing the integration with other circuit components for flexible electronics systems.  相似文献   

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