In this study, the effects of doping with different contents of the rare-earth element yttrium (Y) on the electrical performance of indium zinc oxide (IZO) and bilayer IZO/IYZO thin-film transistors (TFTs) were investigated. Through a rational design, the bilayer IZO/IYZO TFT exhibits the best performance with a Vth of 0.2 V and μFE of 32.6 cm2/V s. X-ray photoelectron spectroscopy band structure analysis demonstrated that, in the IZO/IYZO TFT, a 6-nm highly conductive ultrathin IZO provided free electrons and electron transfer from the IZO layer to the IYZO layer with the formation of band bending, thus increased the carrier mobility of devices. In addition, the 20-nm-thick IYZO layer controlled Ne and Vth by forming a potential barrier (0.38 eV), thereby increasing stability. Moreover, the experimental characterization revealed that Y doping can reduce the carrier concentration, oxygen vacancies, surface defects, and other trap densities of devices. Therefore, the IZO/IYZO TFT demonstrated the best stability with small Vth shifts of −0.9, 0.8, −1.1, and 1.0 V under negative gate bias stress, positive gate bias stress, negative gate bias light illumination stress, and positive gate bias light illumination stress measurements. Overall, the designed IZO/IYZO TFTs open effective pathways for achieving high-performance oxide TFTs.

In this study, hafnium (Hf) was doped into InZnO films and related thin-film transistors (TFTs) were fabricated using co-sputtering. The optimal concentration of Hf doping atoms was obtained by controlling the power of dual targets InZnO and HfO2 and comparing their performances with those of HfInZnO TFTs that were fabricated from a single target, thus achieving high-performance and highly stable HfInZnO TFTs. After optimization, high-performance HfInZnO (PIZO70W-PHfO250W) TFTs with μFE value of 26.1 cm2/V s, SS value of 0.251 V/dec., and Vth value of 0.7 V were obtained. The results of experimental characterization indicate that co-sputtering with Hf doping reduced the oxygen vacancies, surface defects, and other trap densities of the device. Moreover, the co-sputtering prepared HfInZnO TFT exhibited the highest stability for small Vth shifts of 0.8 (−0.9) and 1.2 (−1.6) V under the gate bias and light illumination stress tests. Furthermore, low-frequency noise measurements demonstrated that the optimal Hf doping concentration in the HfInZnO films was controlled by the dual-target co-sputtering method, resulting in a lower number of oxygen vacancies and a lower interface trap density of the devices, thus enhancing the stability of HfInZnO TFTs. Overall, HfInZnO TFTs prepared using dual-target co-sputtering are found to be useful for achieving high-performance oxide TFTs.

Two-dimensional (2D) materials such as WSe2 are potential for advanced electronics because of their ultra-thin geometry and unique electrical properties. Herein, a simplified high-performance WSe2 complementary inverter based on a buried gate is demonstrated on an individual ambipolar WSe2 flake, in which both n-and p-type WSe2 transistors are achieved by local doping. The n-type doping is induced by the donors of benzyl viologen, showing an electron mobility of 28.1 cm2/V7s. In contrast, the p-type one is realized by Ozone exposure with a high mobility of 36.8 cm2/V7s. The buried gate enables enhanced electrostatic coupling, with a supply voltage (Vdd) of 5 V, and the complementary inverter demonstrates a voltage gain beyond 32, almost ideal noise margin approaching 0.5Vdd and low static power consumption. This work paves the way to achieve high-performance 2D material complementary inverters with simplified fabrication process.

Sol–gel-based amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) have gained widespread attention due to their simple process and low cost. Herein, a-IGZO thin films with In : Ga : Zn = 4 : 1 : 4 were fabricated at 400 °C using a sol–gel process, and high-performance a-IGZO TFTs were successfully demonstrated through contact engineering following the guidance of the Schottky–Mott rule, i.e., low work function metals In and Ga with low melting points were employed as contact electrodes. The Ga-contacted and In-contacted devices exhibit superior performance. Specifically, at V_ds = 1 V, the performance of Ga-contacted devices and In-contacted devices exhibited an increased from μ_FE = 5.67 cm² V⁻¹ s⁻¹, V_th = 2.19 V, SS = 0.91 V dec⁻¹, and I_ON/I_OFF = 7.9 × 10⁵ in Cr-contacted devices to μ_FE = 11.40 cm² V⁻¹ s⁻¹, V_th = 1.17 V, SS = 0.56 V dec⁻¹, and I_ON/I_OFF = 2.5 × 10⁶ as well as μ_FE = 12.67 cm² V⁻¹ s⁻¹, V_th = 0.17 V, SS = 0.47 V dec⁻¹, and I_ON/I_OFF = 5.4 × 10⁶. Meanwhile, the contact resistance of Ga-contacted a-IGZO TFTs (1088 kΩ μm) and In-contacted a-IGZO TFTs (403 kΩ μm) are much lower than that of Cr-contacted devices (1890 kΩ μm). The improvement of device performance can be attributed to lower metal work function and superior contact interface quality, which can inhibit the Fermi level pinning effect and maximize the performance of N-channel a-IGZO TFTs. Furthermore, both the positive and negative bias stability of the devices with the different contact were systematically studied. At 3600 s for NBS (V_gs = −20 V) and PBS (V_gs = +20 V), the Ga-contacted and In-contacted devices are shifted by −3.5 V and 11.5 V and −3.1 V and 9.1 V, respectively, which are better than the −10.6 V and 17 V of the Cr-contacted ones. These results further confirm that In and Ga can form high-quality interfaces with a-IGZO. Our results demonstrate a simple and effective strategy to fabricate high-performance sol–gel-based a-IGZO TFTs and provide a solid foundation for its practical application.

Two-dimensional black phosphorus (BP) presents extensive exciting properties attributed to the high mobility and non-dangling bonds uniform surface with simultaneously obtained atomically ultrathin body.