Bias Stability Enhancement in Thin-Film Transistor with a Solution-Processed ZrO2 Dielectric as Gate Insulator

Research Progress of Vertical Channel Thin Film Transistor Device

Thin film transistors (TFTs) as the core devices for displays, are widely used in various fields including ultra-high-resolution displays, flexible displays, wearable electronic skins and memory devices, especially in terms of sensors. TFTs have now started to move towards miniaturization. Similarly to MOSFETs problem, traditional planar structure TFTs have difficulty in reducing the channel's length sub-1μm under the existing photolithography technology. Vertical channel thin film transistors (V-TFTs) are proposed. It is an effective solution to overcome the miniaturization limit of traditional planar TFTs. So, we summarize the different aspects of VTFTs. Firstly, this paper introduces the structure types, key parameters, and the impact of different preparation methods in devices of V-TFTs. Secondly, an overview of the research progress of V-TFTs' active layer materials in recent years, the characteristics of V-TFTs and their application in examples has proved the enormous application potential of V-TFT in sensing. Finally, in addition to the advantages of V-TFTs, the current technical challenge and their potential solutions are put forward, and the future development trend of this new structure of V-TFTs is proposed.

Application of Solution Method to Prepare High Performance Multicomponent Oxide Thin Films

Capacitors play an increasingly important role in hybrid integrated circuits, while the MIM capacitors with high capacitance density and small thickness can meet the needs of high integration. Generally speaking, the films prepared with a single metal oxide dielectric often achieve a breakthrough in one aspect of performance, but dielectric layers are required to be improved to get better performance in leakage current, capacitance density, and transmittance simultaneously in modern electronic devices. Therefore, we optimized the performance of the dielectric layers by using multiple metal oxides. We combined zirconia, yttria, magnesium oxide, alumina, and hafnium oxide with the solution method to find the best combination of these five metal oxides. The physical properties of the multi-component films were measured by atomic force microscopy (AFM), ultraviolet-visible spectrophotometer, and other instruments. The results show that the films prepared by multi-component metal oxides have good transmittance and low roughness. The thicknesses of all films in our experiment are less than 100 nm. Then, metal–insulator–metal (MIM) devices were fabricated. In addition, we characterized the electrical properties of MIM devices. We find that multi-component oxide films can achieve good performances in several aspects. The aluminum-magnesium-yttrium-zirconium-oxide (AMYZO_x) group of 0.6 M has the lowest leakage current density, which is 5.03 × 10⁻⁸ A/cm² @ 1.0 MV/cm. The hafnium-magnesium-yttrium-zirconium-oxide (HMYZO_x) group of 0.8 M has a maximum capacitance density of 208 nF/cm². The films with a small thickness and a high capacitance density are very conducive to high integration. Therefore, we believe that multi-component films have potential in the process of dielectric layers and great application prospects in highly integrated electronic devices.

Thermal effect of annealing-temperature on solution-processed high-k ZrO2 dielectrics

In this paper, a solution-processed zirconium oxide (ZrO₂) dielectric was deposited by spin coating with varying pre-annealing temperatures and post-annealing temperatures. The thermal effect of the pre-annealing and post-annealing process on the structural and electrical properties of ZrO₂ films was investigated. The result shows that the pre-annealing process had a significant impact on the relative porosity and internal stress of ZrO₂ film. A pre-annealing process with a low temperature could not effectively remove the residual solvent, while a high pre-annealing temperature would lead to large internal stress. As for post-annealing temperature, it was found that the post-annealing process can not only reduce internal defects of the ZrO₂ dielectric, but also optimize the interface between the semiconductor and dielectric by lowering the surface defects of the ZrO₂ film. Finally, the TFT with a pre-annealing temperature of 200 °C and post-annealing temperature of 400 °C showed optimized performance, with a mobility of 16.34 cm² (V s)⁻¹, an I_on/I_off of 2.08 × 10⁶, and a subthreshold swing (SS) of 0.17 V dec⁻¹.

In this paper, a solution-processed zirconium oxide (ZrO₂) dielectric was deposited by spin coating with varying pre-annealing temperatures and post-annealing temperatures.

Impact of Oxygen Vacancy on the Photo-Electrical Properties of In₂O₃-Based Thin-Film Transistor by Doping Ga

In this study, amorphous indium gallium oxide thin-film transistors (IGO TFTs) were fabricated by co-sputtering. Three samples with different deposition powers of the In₂O₃ target, namely, sample A with 50 W deposition power, sample B with 60 W deposition power, and sample C with 70 W deposition power, were investigated. The device performance revealed that oxygen vacancies are strongly dependent on indium content. However, when the deposition power of the In₂O₃ target increased, the number of oxygen vacancies, which act as charge carriers to improve the device performance, increased. The best performance was recorded at a threshold voltage of 1.1 V, on-off current ratio of 4.5 × 10⁶, and subthreshold swing of 3.82 V/dec in sample B. Meanwhile, the optical properties of sample B included a responsivity of 0.16 A/W and excellent ultraviolet-to-visible rejection ratio of 8 × 10⁴. IGO TFTs may act as photodetectors according to the results obtained for optical properties.