Low Temperature and Radiation Stability of Flexible IGZO TFTs and their Suitability for Space Applications

In this paper, Low Earth Orbit radiation and temperature conditions are mimicked to investigate the suitability of flexible Indium-Gallium-Zinc-Oxide transistors for lightweight space-wearables. Such wearable devices could be incorporated into spacesuits as unobtrusive sensors such as radiation detectors or physiological monitors. Due to the harsh environment to which these space-wearables would be exposed, they have to be able to withstand high radiation doses and low temperatures. For this reason, the impacts of high energetic electron irradiation with fluences up to
$10^{12}\mathbf{e}^{-}/\mathbf{cm}^{2}$
and low operating temperatures down to 78 K, are investigated. This simulates 278 h in a Low Earth Orbit. The threshold voltage and mobility of transistors that were exposed to e- irradiation are found to shift by
$+0.09\pm 0.05\mathbf{V}$
and
$-0.6\pm 0.5\mathbf{cm}^{2}\mathbf{V}^{-1}\mathbf{s}^{-1}$
. Subsequent low temperature exposure resulted in additional shifts of
$+0.38\mathbf{V}$
and
$-5.95\ \mathbf{cm}^{2}\mathbf{V}^{-1}\mathbf{s}^{-1}$
for the same parameters. These values are larger than the ones obtained from non-irradiated reference samples. If this is considered during the systems' design, these devices can be used to unobtrusively integrate sensor systems into space-suits.