Search Results (6)

In the era of digital transformation, a memristor and memristive circuit can provide an advanced computer architecture that efficiently processes a vast quantity of data. With the unique characteristic of memristor, a memristive crossbar array has been utilized for realization of nonvolatile memory, logic-in-memory circuit, and neuromorphic system. However, the crossbar array architecture suffers from leakage of current, known as the sneak current, which causes a cross-talk interference problem between adjacent memristor devices, leading to an unavoidable operational error and high power consumption. Here, we present an amorphous In-Sn-Zn-O (a-ITZO) oxide semiconductor-based selector device to address the sneak current issue. The a-ITZO-selector device is realized with the back-to-back Schottky diode with nonlinear current-voltage (I-V) characteristics. Its nonlinearity is dependent on the oxygen plasma treatment process which can suppress the surface electron accumulation layer arising on the a-ITZO surface. The a-ITZO-selector device shows reliable characteristics against electrical stress and high temperature. In addition, the selector device allows for a stable read margin over 1 Mbit of memristor crossbar array. The findings may offer a feasible solution for the development of a high-density memristor crossbar array. Full article

In-Sn-Zn oxide (ITZO) nanocomposite films have been investigated extensively as a potential material in thin-film transistors due to their good electrical properties. In this work, ITZO thin films were deposited on glass substrates by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The influence of the duty cycle (pulse off-time) on the microstructures and electrical performance of the films was investigated. The results showed that ITZO thin films prepared by HiPIMS were dense and smooth compared to thin films prepared by direct-current magnetron sputtering (DCMS). With the pulse off-time increasing from 0 μs (DCMS) to 2000 μs, the films’ crystallinity enhanced. When the pulse off-time was longer than 1000 μs, In₂O₃ structure could be detected in the films. The films’ electrical resistivity reduced as the pulse off-time extended. Most notably, the optimal resistivity of as low as 4.07 × 10⁻³ Ω·cm could be achieved when the pulse off-time was 2000 μs. Its corresponding carrier mobility and carrier concentration were 12.88 cm²V⁻¹s⁻¹ and 1.25 × 10²⁰ cm⁻³, respectively. Full article

InSnZnO thin-film transistors (ITZO TFTs), having high carrier mobility, guarantee the benefits of potential applications in the next generation of super-high-definition flat-panel displays. However, the impact of photo-excitation on the leakage current and negative bias stress (NBIS) of ITZO TFTs must be further explored. In this study, the ITZO thickness (T_ITZO) is designed to tailor the initial performance of devices, especially for the 100 nm T_ITZO TFT, producing excellent electrical properties of 44.26 cm²V⁻¹s⁻¹ mobility, 92 mV/dec. subthreshold swing (SS), 0.04 V hysteresis, and 3.93 × 10¹⁰ ON/OFF ratio, which are superior to those of the reported ITZO TFTs. In addition, incident light coupled with tunable photon energy is introduced to monitor the leakage current of various T_ITZO devices. The OFF-current results demonstrate that under the identical photon energy, many more electrons are photo-excited for the thicker T_ITZO TFTs. NBIS-induced V_th shift and SS deterioration in all TFTs are traced and analyzed in real time. As the T_ITZO thickens to near Debye length, the degree of degradation is exacerbated. When the thickness further increases, the notorious instability caused by NBIS is effectively suppressed. This study provides an important research basis for the application of ITZO-based TFTs in future displays. Full article

Thin-film transistor (TFT) devices composed of metal oxide semiconductors have attracted tremendous research attention globally in recent years. Owing to their ability to offer mobility, metal oxide semiconductor materials can enable high-performance TFTs for next-generation integrated display devices. Nevertheless, further breakthroughs of metal oxide TFTs are mainly obstructed by their long-term variability, the reason for which is not yet fully understood. Herein, TFTs based on InSnZnO (ITZO) with various thicknesses (T_ITZO) were prepared and their long-term stabilities under test temperatures and drain current stress were investigated. The results indicate that ITZO TFTs exhibit outstanding electrical properties regardless of the T_ITZO, including a high saturated mobility of over 35 cm²V⁻¹s⁻¹ and sharp subthreshold swing. Note that the transfer and output characteristic curves of the device with a thick T_ITZO of 100 nm express an abnormal current surge when high gate and drain voltages are exerted, which is attributed to the floating body effect, caused when the imposed electric field induces impact ionization near the drain side. More interestingly, these drain current stress results further suggest that the abnormal shift behavior of the electrical properties of the ITZO TFTs with a T_ITZO of greater than 75 nm is observed to deteriorate gradually with increasing temperature and drain current bias. This study addresses that such a degradation effect should be restrained for the operation of high-mobility devices. Full article

In-Sn-Zn oxide (ITZO) thin films have been studied as a potential material in flat panel displays due to their high carrier concentration and high mobility. In the current work, ITZO thin films were deposited on glass substrates by high-power impulse magnetron sputtering (HiPIMS) at room temperature. The influence of the sputtering power on the microstructures and electrical performance of ITZO thin films was investigated. The results show that ITZO thin films prepared by HiPIMS were dense and smooth. There were slight variations in the composition of ITZO thin films deposited at different sputtering powers. With the sputtering power increasing from 100 W to 400 W, the film’s crystallinity was enhanced. When the sputtering power was 400 W, an In₂O₃ (104) plane could be detected. Films with optimal electrical properties were produced at a sputtering power of 300 W, a carrier mobility of 31.25 cm²·V⁻¹·s⁻¹, a carrier concentration of 9.11 × 10¹⁸ cm⁻³, and a resistivity of 2.19 × 10⁻⁴ Ω·m. Full article

We fabricated the transparent non-volatile memory (NVM) of a bottom gate thin film transistor (TFT) for the integrated logic devices of display applications. The NVM TFT utilized indium–tin–zinc–oxide (ITZO) as an active channel layer and multi-oxide structure of SiO₂ (blocking layer)/Si-rich SiO_X (charge trapping layer)/SiO_XN_Y (tunneling layer) as a gate insulator. The insulators were deposited using inductive coupled plasma chemical vapor deposition, and during the deposition, the trap states of the Si-rich SiOx charge trapping layer could be controlled to widen the memory window with the gas ratio (GR) of SiH₄:N₂O, which was confirmed by fourier transform infrared spectroscopy (FT-IR). We fabricated the metal–insulator–silicon (MIS) capacitors of the insulator structures on n-type Si substrate and demonstrated that the hysteresis capacitive curves of the MIS capacitors were a function of sweep voltage and trap density (or GR). At the GR6 (SiH₄:N₂O = 30:5), the MIS capacitor exhibited the widest memory window; the flat band voltage (ΔV_FB) shifts of 4.45 V was obtained at the sweep voltage of ±11 V for 10 s, and it was expected to maintain ~71% of the initial value after 10 years. Using the Si-rich SiO_X charge trapping layer deposited at the GR6 condition, we fabricated a bottom gate ITZO NVM TFT showing excellent drain current to gate voltage transfer characteristics. The field-effect mobility of 27.2 cm²/Vs, threshold voltage of 0.15 V, subthreshold swing of 0.17 V/dec, and on/off current ratio of 7.57 × 10⁷ were obtained at the initial sweep of the devices. As an NVM, ΔV_FB was shifted by 2.08 V in the programing mode with a positive gate voltage pulse of 11 V and 1 μs. The ΔV_FB was returned to the pristine condition with a negative voltage pulse of −1 V and 1 μs under a 400–700 nm light illumination of ~10 mWcm⁻² in erasing mode, when the light excites the electrons to escape from the charge trapping layer. Using this operation condition, ~90% (1.87 V) of initial ΔV_FB (2.08 V) was expected to be retained over 10 years. The developed transparent NVM using Si-rich SiOx and ITZO can be a promising candidate for future display devices integrating logic devices on panels. Full article