Serially connected tantalum and amorphous indium tin oxide for sensing the temperature increase in IGZO thin-film transistor backplanes

Abstract

A temperature sensor embedded in an In-Ga-Zn oxide (IGZO) TFT was evaluated after fabrication to facilitate monitoring of the temperature distribution on a thin-film transistor (TFT) array. Because the proposed temperature sensor uses the same material as the TFT, no additional process or material is required. Moreover, it can be used as a light shield layer because the temperature sensor is located on a TFT. The temperature sensor used in this study was serially connected to indium tin oxide and a metal. As the temperature increased to 120 °C, the output voltage of the temperature sensor increased to 176.6 mV. The sensitivity, hysteresis, and repeatability were 0.85 mV/°C, 3.56 %, and 0.04 %, respectively. The temperature sensor was integrated into an amorphous IGZO bottom-gate TFT. The TFT exhibited a field-effect mobility of 8.2 cm2V−1·s−1 and threshold voltage of 5.2 V. As the drain current increased from 300 µA to 1.1 mA, the temperature increased from 26 to 32.9 °C, and the output voltages of the temperature sensor augmented from 66 to 76 mV. The integrated temperature sensors enable us to measure the temperature distribution in a display panel and compensate for image deterioration due to increased temperature.