Transparent AMOLED display driven by hafnium-indium-zinc oxide thin film transistor array

The fabrication and electrical characteristics of transparent hafnium-indium-zinc oxide (HIZO) thin film transistors (TFTs) are presented in detail. The devices incorporate an etch stopper structure, which may consist of either a single SiO_x layer deposited by plasma enhanced chemical vapor deposition (PECVD) at 150 °C, or a dual stack of SiO_x layers grown at 150 °C and 350 °C. The electrical properties suggest that the latter is more effective at protecting the underlying oxide semiconductor in the course of source-drain etching, hence resulting in high performance transparent TFTs. The saturation mobility and the subthreshold swing of the transparent HIZO TFTs fabricated with the dual etch stopper are 7.6 cm²/Vs and 0.30 V/decade, respectively. A 4-inch QVGA (320 × 240) transparent active matrix organic light emitting diode (AMOLED) display was realized using a backplane array of the above TFTs.