High mobility crystallized stacked-channel thin-film transistors induced by low-temperature thermal annealing

A high mobility crystallized stacked-channel thin-film transistor (TFT) was fabricated and characterized. The stacked IGO/IGZO channel film consisting of an In-rich IGO layer and a conventional IGZO layer was fabricated by atomic layer deposition technology, where the upper layer of amorphous IGZO is induced into nanocrystals by the lower layer of preferentially oriented polycrystalline IGO during thermal annealing at a low temperature of 300 °C. The preferential growth of nanocrystalline IGZO with matched crystal structure in the channel favors the transport of electrons. In addition, the accumulation of a large number of electrons at the heterojunction due to energy band bending provides a strong guarantee for high mobility. The crystallized stacked IGO/IGZO TFT exhibits a superior field effect mobility of 95.7 cm2 V−1 s−1, which is 55.9% higher than that of single-layer IGO TFT. At the same time, the stability of the device was also dramatically improved. The proposed strategy is a simple and promising approach to prepare high performance TFTs for future display and semiconductor applications.