Flexible IGZO TFTs and Their Suitability for Space Applications

Abstract

In this paper, low earth orbit radiation (LEO), temperature, and magnetic field conditions are mimicked to investigate the suitability of flexible InGaZnO transistors for lightweight space wearables. More specifically, the impacts of high energetic electron irradiation with fluences up to 1012 e-/cm2, low operating temperatures down to 78 K and magnetic fields up to 11 mT are investigated. This simulates 278 h in LEO. The threshold voltage and mobility of transistors that were exposed to e- irradiation are found to shift by +(0.09 ± 0.05) V and -(0.6 ± 0.5) cm2V-1s-1. Subsequent low temperature exposure resulted in additional shifts of +0.38 V and -5.95 cm2V-1s-1 for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. Conversely, the performance of the devices was observed not to be significantly affected by the magnetic fields. Finally, a Cascode amplifier presenting a voltage gain of 10.3 dB and a cutoff frequency of 1.2 kHz is demonstrated after the sample had been irradiated, cooled down, and exposed to the magnetic fields. If these notions are considered during the systems design, these devices can be used to unobtrusively integrate sensor systems into space suits.

Keywords

• Flexible electronics
• space applications
• amorphous oxides
• wearables
• thin film transistors