InSnO (ITO) thin-film transistors (TFTs) attract much attention in fields of displays and low-cost integrated circuits (IC). In the present work, we demonstrate the high-performance, robust ITO TFTs ...that fabricated at process temperature no higher than 100 °C. The influences of channel thickness (t
, respectively, 6, 9, 12, and 15 nm) on device performance and positive bias stress (PBS) stability of the ITO TFTs are examined. We found that content of oxygen defects positively correlates with t
, leading to increases of both trap states as well as carrier concentration and synthetically determining electrical properties of the ITO TFTs. Interestingly, the ITO TFTs with a t
of 9 nm exhibit the best performance and PBS stability, and typical electrical properties include a field-effect mobility (µ
) of 37.69 cm
/Vs, a V
of -2.3 V, a SS of 167.49 mV/decade, and an on-off current ratio over 10
. This work paves the way for practical application of the ITO TFTs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The electrical recovery behaviors of the amorphous InGaZnO thin-film transistors (a-IGZO TFTs) after positive gate-bias stress (PBS) are investigated. The TFTs show an evident sub-threshold swing ...(SS) degradation after the PBS removal when the channel layer is deposited at relatively high oxygen flow rates, although they exhibit a parallel positive shift in the transfer characteristics during the PBS. It is inferred that the SS degradation results from the oxygen interstitial defects created in the a-IGZO channel during the PBS, which are in the octahedral configuration and are usually more easily created in the oxygen-rich a-IGZO channel layer. They are electrically inactive during the PBS due to the "negative U" behavior and then become relaxed and electrically active during the recovery process, leading to the SS degradation during the recovery process.
In this work, fully transparent high performance double-channel indium-tin-oxide/Al-Sn-Zn-O thin-film transistors (ITO/ATZO TFTs) are successfully fabricated on glass by radio frequency (RF) ...magnetron sputtering. The ITO layer acts as the bottom channel layer to increase the channel carrier concentration. The top ATZO channel layer, which is deposited via high oxygen partial pressure in the sputtering process, is useful to control the minimum off-state current. After annealing, the ITO/ATZO TFT demonstrates outstanding electrical performances, including a high ON/OFF current ratio (I
/I
) of 3.5 × 10
, a steep threshold swing (SS) of 142.2 mV/decade, a superior saturation mobility (μ
) of 246.0 cm
/Vs, and a threshold voltage V
of 0.5 V. The operation mechanisms for double-channel structures are also clarified.
High-performance transparent low-temperature top-gate type aluminum doped zinc oxide (AZO) thin-film transistors (TFTs) ( W / L =100 or 10 μm) are successfully fabricated on glass substrate. All the ...process temperature is below 100°C. For VG =-2 to 5 V, the TFTs using sputtering deposit AZO layer at room temperature as channel layer exhibits excellent properties, such as a saturation mobility μ s of 285 cm 2 /V·s, a linear field effect mobility μ l of 143 cm 2 /V·s, a threshold voltage Vth of 0.9 V, a steep subthreshold swing of 108 mV/decade, a low off-state current value I off of 5×10 -13 A, a high ON/OFF ratio of 2×10 9 and a high transmittance of 82.5%. The results highlight that excellent device performance can be realized in AZO TFTs. Note that this is the best performance of AZO TFT ever reported.
The effect of oxygen adsorption at the back channel of a-IGZO thin-film transistors (TFTs) is investigated. It is shown that for TFTs with the channel layer sputter-deposited at a high O 2 /Ar flow ...rate ratio (RO/Ar), the threshold voltages in vacuum and O 2 ambient do not show any difference; for devices fabricated at a low RO/Ar, the threshold voltages in vacuum are lower than those in O 2 . In addition, the devices in O 2 show a more significant threshold voltage shift than those in vacuum do under a positive gate bias stress. The surface-state model is used to explain this observation. It is inferred that the oxygen adsorptions are physical and chemical, respectively, in the high-and low-RO/Ar cases, and the transition from physical to chemical adsorption occurs when a positive gate bias stress is applied.
Oxide thin-film transistors (TFTs) are of increasing interest in the field of advanced displays. In this work, we explore Al, InSnO (ITO), Ti, and Mo as source/drain electrodes of ITO TFTs. A ...comparison study is conducted on the electrical properties of ITO TFTs with the four categories of source/drain electrodes. Interestingly, the ITO TFT with an Al source/drain electrode exhibits better device performance, such as a field-effect mobility (μFE) of 26.45 cm2/Vs, a reasonable turn-on voltage (VON) of 2.7 V, and a steep subthreshold swing (SS) of 201.50 mV/decade. The contact properties of ITO TFTs are further analyzed, and the results show that the device with an Al electrode exhibits lower contact resistance than the other devices. However, the devices with the four electrode materials all reveal excellent stability under negative bias illumination stress (NBIS) with |ΔVTH| < 1 V. This work paves the way for the practical applications of ITO TFTs in next-generation displays.
We have fabricated fully transparent high performance flexible nickel-doped zinc oxide thin-film transistors (NZO TFTs) on flexible plastic substrates using magnetron sputtering. The effects of ...active layer thickness on the performance of NZO TFTs was investigated.We found that the channel layer thickness has a notable influence on the characteristics of NZO TFTs. The electrical characteristics of NZO TFTs reached the optimization when the active channel layer thickness was 71 nm, with a low off-current lower than 1 pA, a high on/off drain current ratio of 2.1 × 10 9 , a high saturation mobility of 27.5 cm 2 · V -1 · s -1 , a steeper subthreshold swing of 67 mV/decade, and a low threshold voltage of 1.88 V. It is demonstrated that NZO is a promising active channel layer materials for future transparent flexible displays.
Full transparent high-performance tin-zinc-oxide thin-film transistors (TZO TFTs) had been successfully fabricated on flexible plastic substrate by radio frequency (RF) sputtering. Excellent ...properties of TZO TFT with L G = 10 μm gate length were realized, namely high saturation mobility (μ s ) of 175 cm 2 /V · s, high linear mobility (μl) of 127 cm 2 /V · s, a suitable threshold voltage (V th ) of 1.81 V, a steep subthreshold swing (SS) of 220 mV/decade, an ON/OFF current ratio (I ON /IO FF ) of ~1 × 10 8 , and good transmittance of 91.9%, which compare favorably to those made on glass substrates. Mechanical stability of flexible TZO TFTs was investigated by bending tests. The flexible TZO TFTs exhibited good electrical performance, good uniformity, and good flexibility. Thereby, we demonstrated the feasibility of high-performance TZO TFTs for flexible display applications.
Transparent electrodes are a core component for transparent electron devices, photoelectric devices, and advanced displays. In this work, we fabricate fully-transparent, highly-conductive Al-doped ...ZnO (AZO) films using an atomic layer deposition (ALD) system method of repeatedly stacking ZnO and Al
O
layers. The influences of Al cycle ratio (0, 2, 3, and 4%) on optical property, conductivity, crystallinity, surface morphology, and material components of the AZO films are examined, and current conduction mechanisms of the AZO films are analyzed. We found that Al doping increases electron concentration and optical bandgap width, allowing the AZO films to excellently combine low resistivity with high transmittance. Besides, Al doping induces preferred-growth-orientation transition from (002) to (100), which improves surface property and enhances current conduction across the AZO films. Interestingly, the AZO films with an Al cycle ratio of 3% show preferable film properties. Transparent ZnO thin film transistors (TFTs) with AZO electrodes are fabricated, and the ZnO TFTs exhibit superior transparency and high performance. This work accelerates the practical application of the ALD process in fabricating transparent electrodes.
Coplanar bottom-gate aluminum-zinc-oxide (AZO) thin film transistors (TFTs) with aluminum (Al) capping layers were fabricated in this work. The influences of the Al capping layer thickness and the ...post-annealing condition on the performance of the AZO-TFTs were investigated. Results show that the performance of the AZO-TFTs are enhanced significantly by introducing the Al capping layer on back channel, with saturation mobility increasing dramatically from 0.128 to 12.6 cm 2 /V · s. The enhancement is ascribed to the diffusion of Al atoms into the AZO thin film and thus induced crystallization improvement.
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