Amorphous indium gallium zinc oxide thin film transistors (a-IGZO-TFTs): Exciting prospects and fabrication challenges

In today's consumer electronics market, major manufacturing companies may be profitable and scalable thanks to technologies like thin-film transistors (TFTs). TFTs are found in TVs, smartphones, laptops, brain-like synaptic transistors, back-planes in CMOS image sensors, integrated circuits (ICs), flexible & wearable electronics, power switching circuits, back-end-of-line (BEOL) transistor elements in 3D-logic and cell transistors in dynamic random-access memory (DRAM). They have also been proposed as a potential solution for flexible CPUs. A high mobility of 74.4 cm²/Vs and I_ON/I_OFF of 3.39 × 10⁹ and a V_ON of less than ±0.1 V and a SS of less than 0.1 V/dec were achieved in a-IGZO based TFTs. Numerous efforts have been made to enhance the a-IGZO TFTs' electrical characteristics by optimizing the fabrication process. Numerous studies have also addressed the instability problems, such as the a-IGZO devices' hot-carrier effects, self-heating, and charge-trapping. TFTs with a-IGZO are being extensively studied adopting the a vertical-channel approach in order to be used in 3-D electronic devices. This article reviews the recent developments in materials and architectures, performance overview of IGZO-TFTs, advances and challenges in fabrication technologies and reliability issues & degradation mechanisms of IGZO-TFTs.