An increasing number of new applications beyond displays has been reported for the amorphous oxide semiconductors, especially Indium–gallium–zinc–oxide (IGZO), based flexible thin-film transistors (TFTs). The atomic composition of the IGZO target was In:Ga:Zn= 2:2:2. From sensors to microprocessors, the flexible IGZO TFTs aim to diversify the functionality of silicon legacy nodes. In this work, IGZO enhancement-mode NMOS TFTs, with a minimum channel length of 5 μm, were fabricated on flexible polyimide substrates at temperatures below 150 °C. We observed a small dependency of threshold voltage (2.23±0.06 V) and saturation mobility (3.74±0.57 cm ² /V-s) with the channel width to length ratio. The IGZO TFTs were interconnected in the saturation load configuration for the successful demonstration of basic logic gates (inverter, NAND and NOR gates), a seven-stage ring oscillator, an XOR gate, and a half-adder. Due to this configuration, their output voltage was limited to V _DD -V _TH . Their electrical response was evaluated with direct and alternating voltages at a maximum input frequency of 500 Hz and a power supply of 5 V. Under ac analysis their fall/rise time were in the 3-43/148-212 μs range. The inverter, as the fundamental building block for digital circuits, was also tested at different bending radius from 10 to 2.5 mm. Our results are oriented to a better understanding of the flexible IGZO TFT technology to reach reliable integrated circuits.

In the last few years, Thin Film Transistors (TFTs) based on materials such as amorphous Indium–Gallium–Zinc Oxide (a-IGZO) have gained interest in large-area and low-cost electronics due to their high carrier mobility, high on/off current ratio, low off-state current, and steep subthreshold slope. These characteristics make IGZO TFTs suitable for radio-frequency identification (RFID) tags, analog-to-digital converters (ADCs), logic circuits, sensors, and analog components, including operational amplifiers (OPAMPs). This work presents the implementation and characterization of an OPAMP based on n-type a-IGZO TFTs fabricated on glass substrate. Two previously reported design strategies were integrated: a positive feedback network to increase the output impedance and a topology to enhance the transconductance of the driver transistors, both in the differential input stage. A gain of 26 dB, a bandwidth of 2.4 kHz, a gain–bandwidth product (GBWP) of 48 kHz, and a phase margin of 64° were obtained, which confirms the reliability of the design and the fabrication process.

Amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) have emerged as promising candidates for next-generation large-area and low-power electronics due to their high mobility, low leakage current, and compatibility with low-temperature fabrication on flexible or transparent substrates. In this work, we report the fabrication of bottom-gate a-IGZO NMOS TFTs using HfO₂ as high-k gate dielectric and Mo top contacts. The devices were electrically characterized through capacitance–voltage (C–V) and current–voltage (I–V) measurements, from which key parameters were extracted. Based on these transistors, we designed, fabricated, and characterized inverters employing four different load configurations: resistive, diode, depletion, and pseudo-CMOS. A comparative analysis was performed in terms of voltage transfer characteristics (VTCs), gain, and noise margins, highlighting that depletion-load inverters offer the highest gain and robust noise margins. Finally, a two-channel multiplexer was designed and fabricated. The multiplexer was characterized under both square and sinusoidal input signals up to 1 kHz, demonstrating correct channel selection and robust switching behavior. These results confirm the potential of a-IGZO TFT-based circuits as building blocks for low-power and high-reliability digital and mixed-signal electronics.