ITO-Channel Ferroelectric-Gate Thin Film Transistor with Large On/off Current Ratio

2007 ◽  
Vol 997 ◽  
Author(s):  
Eisuke Tokumitsu ◽  
Masaru Senoo ◽  
Etsu Shin ◽  
Tomofumi Fujimura
Keyword(s):  
Thin Film ◽  
Indium Tin Oxide ◽  
Thin Film Transistor ◽  
Sol Gel ◽  
Mechanical Polishing ◽  
Gate Insulator ◽  
Polishing Process ◽  
Current Ratio ◽  
Subthreshold Voltage ◽  
Voltage Swing

AbstractIndium tin oxide (ITO)-channel ferroelectric-gate thin film transistor (TFT) with large on/off current ratio is demonstrated by using mechanical polishing process to planarize the surface of ferroelectric bottom gate insulator (Bi,La)4Ti3O12 (BLT). It is shown that the mechanical polishing of the sol-gel derived polycrystalline ferroelectric BLT films causes no degradation in electrical properties. ITO channel layer was then deposited on the planarized BLT gate insulator to fabricate ferroelectric-gate TFTs. The off-current of the ITO/BLT TFT fabricated with the polishing process is drastically reduced to around 10−12 A, which is four orders of magnitude lower than that of the TFT fabricated without the polishing process. The obtained on/off current ratio is more than 107. In addition, a subthreshold voltage swing as small as 200 mV/decade was obtained.

scholarly journals Demonstration on Ferroelectric-gate Thin Film Transistor NAND-type Array with Disturbance-free Operation

2019 ◽  
Vol 35 (2) ◽  
Author(s):  
Bui Nguyen Quoc Trinh
Keyword(s):  
Thin Film ◽  
Thin Film Transistor ◽  
Sol Gel ◽  
Gate Insulator ◽  
Current Ratio ◽  
Memory State ◽  
Small Loss ◽  
Memory Circuit ◽  
Novel Concept ◽  
Data Reading

Abstract: A novel concept of NAND memory array has been proposed by using only ferroelectric-gate thin film transistors (FGTs), whose structure is constructed from a sol-gel ITO channel and a sol-gel stacked ferroelectric between Bi3.25La0.75Ti3O12 and PbZr0.52TiO0.48O3 (BLT/PZT) gate insulator. Interestingly, ferroelectric cells with a wide memory window of 3 V and a large on/off current ratio of 6 orders, have been successfully integrated in a NAND memory circuit. To protect data writing or reading from disturbance, ferroelectric transistor cells are directly used, instead of paraelectric transistor cells as usual. As a result, we have verified disturbance-free operation for data reading and writing, with a small loss of the memory state and a low power consumption, in principle. Keywords: ITO, PZT, NAND, FeRAM, ferroelectric.

scholarly journals Effect of Coercive Voltage and Charge Injection on Performance of a Ferroelectric-Gate Thin-Film Transistor

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
P. T. Tue ◽  
T. Miyasako ◽  
E. Tokumitsu ◽  
T. Shimoda
Keyword(s):  
Thin Film ◽  
Indium Tin Oxide ◽  
Thin Film Transistor ◽  
Charge Injection ◽  
Memory Window ◽  
Gate Insulator ◽  
Insulator Layer ◽  
Capping Layer ◽  
Insulator Layers ◽  
Injection Effect

We adopted a lanthanum oxide capping layer between semiconducting channel and insulator layers for fabrication of a ferroelectric-gate thin-film transistor memory (FGT) which uses solution-processed indium-tin-oxide (ITO) and lead-zirconium-titanate (PZT) film as a channel layer and a gate insulator, respectively. Good transistor characteristics such as a high “on/off” current ratio, high channel mobility, and a large memory window of 108, 15.0 cm2 V−1 s−1, and 3.5 V were obtained, respectively. Further, a correlation between effective coercive voltage, charge injection effect, and FGT’s memory window was investigated. It is found that the charge injection from the channel to the insulator layer, which occurs at a high electric field, dramatically influences the memory window. The memory window’s enhancement can be explained by a dual effect of the capping layer: (1) a reduction of the charge injection and (2) an increase of effective coercive voltage dropped on the insulator.

Non-volatile Thin Film Transistors Using Ferroelectric/ITO Structures.

2004 ◽  
Vol 830 ◽  
Author(s):  
Eisuke Tokumitsu ◽  
Takaaki Miyasako ◽  
Masaru Senoo
Keyword(s):  
Thin Film ◽  
Indium Tin Oxide ◽  
Thin Film Transistors ◽  
Sol Gel ◽  
Rf Sputtering ◽  
Drain Current ◽  
Gate Insulator ◽  
Pzt Film ◽  
Gate Structure ◽  
Current Saturation

ABSTRACTWe report ferroelectric-gate thin film transistors (TFTs) using indium tin oxide (ITO) as a channel material. Bottom-gate structure TFTs have been fabricated using ferroelectric Pb(Zr, Ti)O3 (PZT) film as a gate insulator and ITO channel. Ferroelectric and ITO layers were formed by the sol-gel technique and RF sputtering, respectively. Drain current-drain voltage (ID-VD) characteristics of PZT/ITO ferroelectric-gate TFTs exhibit typical n-channel transistor operations with clear current saturation and electrical properties were improved by the post annealing. Drain current-gate voltage (ID-VG) characteristics demonstrate clear counterclockwise hysteresis loop due to the ferroelectric gate insulator. The obtained memory window is 2 V. The on/off current ratio of more than 102 has been obtained, which indicates that the ITO channel is sufficiently depleted by the ferroelectric polarization.

Fabrication of IGZO and In2O3-channel Ferroelectric-gate Thin Film Transistors

2010 ◽  
Vol 1250 ◽  
Author(s):  
tomohiro Oiwa ◽  
Eisuke Tokumitsu
Keyword(s):  
Field Effect ◽  
Charge Injection ◽  
Drain Current ◽  
Gate Insulator ◽  
Field Effect Mobility ◽  
Current Ratio ◽  
Injection Type ◽  
Subthreshold Voltage ◽  
A Charge ◽  
Voltage Swing

AbstractWe have fabricated and characterized ferroelectric-gate TFTs using In-Ga-Zn-O (IGZO) or In2O3 as a channel material. The ferroelectric gate insulator used in this work is (Bi,La)4Ti3O12 (BLT). We observed normal n-channel transistor operation for both IGZO and In2O3-channel TFTs. However, a charge injection type hysteresis was observed for IGZO channel TFTs in drain current – gate voltage (ID-VG) characteristics. Post fabrication anneal at 300oC reduced the charge-injection-tyoe hystereesis and the subthreshold swing was also improved from 0.27 to 0.19 V/decade. On the other hand, when the In2O3 was used as a channel, hysteresis due to the ferroelectric gate insulator was clearly observed in ID-VG characteristics. A memory window of 2V, a subthreshold voltage swing of 0.35V/decade, a field-effect mobility of 1.6 cm2/Vs, and a on/off drain current ratio of more than 10^6 were obtained.

scholarly journals Influence of Active Channel Layer Thickness on SnO2 Thin-Film Transistor Performance

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 200
Author(s):  
Do Won Kim ◽  
Hyeon Joong Kim ◽  
Changmin Lee ◽  
Kyoungdu Kim ◽  
Jin-Hyuk Bae ◽  
...  
Keyword(s):  
Thin Film ◽  
Field Effect ◽  
Thin Film Transistor ◽  
Sol Gel ◽  
Precursor Concentration ◽  
Sno2 Thin Film ◽  
Field Effect Mobility ◽  
Si Substrates ◽  
Channel Layer ◽  
Active Channel

Sol-gel processed SnO2 thin-film transistors (TFTs) were fabricated on SiO2/p+ Si substrates. The SnO2 active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO2 active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (SS), and increased threshold voltage (Vth), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO2 TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm2/Vs, an SS of 1.99, an Ion/Ioff value of ~4.0 × 107, and showed enhancement mode operation and positive Vth, equal to 9.83 V.

scholarly journals Performance Improvement of ZnSnO Thin-Film Transistors with Low-Temperature Self-Combustion Reaction

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1099
Author(s):  
Ye-Ji Han ◽  
Se Hyeong Lee ◽  
So-Young Bak ◽  
Tae-Hee Han ◽  
Sangwoo Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Low Cost ◽  
Thermal Analyses ◽  
Thin Film Transistor ◽  
Sol Gel ◽  
Annealing Temperatures ◽  
Zinc Tin Oxide ◽  
Thermal Limitation

Conventional sol-gel solutions have received significant attention in thin-film transistor (TFT) manufacturing because of their advantages such as simple processing, large-scale applicability, and low cost. However, conventional sol-gel processed zinc tin oxide (ZTO) TFTs have a thermal limitation in that they require high annealing temperatures of more than 500 °C, which are incompatible with most flexible plastic substrates. In this study, to overcome the thermal limitation of conventional sol-gel processed ZTO TFTs, we demonstrated a ZTO TFT that was fabricated at low annealing temperatures of 350 °C using self-combustion. The optimized device exhibited satisfactory performance, with μsat of 4.72 cm2/V∙s, Vth of −1.28 V, SS of 0.86 V/decade, and ION/OFF of 1.70 × 106 at a low annealing temperature of 350 °C for one hour. To compare a conventional sol-gel processed ZTO TFT with the optimized device, thermogravimetric and differential thermal analyses (TG-DTA) and X-ray photoelectron spectroscopy (XPS) were implemented.

Metal Oxide Thin Film Transistor with Nano Inorganic Gate Dielectric : Material Chemistry, Nanoscience, Solution Processing and Electronics

2021 ◽  
Vol 23 (09) ◽  
pp. 1078-1085
Author(s):  
A. Kanni Raj ◽  
Keyword(s):  
Thin Film ◽  
Metal Oxide ◽  
Gate Dielectric ◽  
Dielectric Material ◽  
Thin Film Transistor ◽  
Sol Gel ◽  
Oxide Thin Film ◽  
Barium Zirconate ◽  
Operating Voltage ◽  
Metal Oxide Thin Film

Indium Lead Oxide (ILO) based Metal Oxide Thin Film Transistor (MOTFT) is fabricated with Lead Barium Zirconate (PBZ) gate dielectric. PBZ is formed over doped silicon substrate by cheap sol-gel process. Thin film PBZ is analysed with X-ray Diffraction (XRD), Ultra-Violet Visible Spectra (UV-Vis) and Atomic Force Microscope (AFM). IZO is used as bottom gate to contact Thin Film Transistor (TFT). This device needs only 5V as operating voltage, and so is good for lower electronics <40V. It shows excellent emobility 4.5cm2/V/s, with on/off ratio 5×105 and sub-threshold swing 0.35V/decade.

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