Demonstration of α-InGaZnO TFT Nonvolatile Memory Using TiAlO Charge Trapping Layer

Amorphous indium gallium zinc oxide (α-InGaZnO) thin-film transistors using as nonvolatile memories (TFT-NVMs) with an Al₂O₃/TiAlO/Al₂O₃ charge trapping engineered structure have been demonstrated experimentally at low thermal budget of 300 °C. The high-k composite TiAlO layer with a high trap state density and a high dielectric constant was prepared by sputtering at room temperature as a charge trapping material. According to the high-resolution transmission electron microscopy analyses, the Al₂O₃/TiAlO/Al₂O₃ gate stack exhibited sharp interfaces and a uniform distribution of Ti and Al elements in the TiAlO film. The programming and retention characteristics of the fabricated α-InGaZnO TFT-NVMs were investigated in detail. The TFT-NVMs exhibited excellent programming characteristics with a large memory window of around 5.74 V under a 16 V programming voltage. It can also maintain a memory margin of about 5 V after 10 years, indicating only ~15% charge loss. This paper suggests that α-InGaZnO TFT-NVMs using the high-k TiAlO composite material as the charge trapping material are promising for future nonvolatile memories applications in display technology, flexible and wearable electronics.