Temperature dependence of the piezotronic and piezophototronic effects in flexible GaN thin films

Flexible devices operated at a cryogenic temperature are required for significant applications, such as sensors in thermal imaging and infrared and nuclear particle detectors. Hence, in this study, comprehensive temperature dependence was performed on flexible GaN thin films from 225 K to 325 K under 0.0–0.3% strains to investigate the piezotronic and piezophototronic effects. The GaN thin-film device strongly depends on the applied temperature, and the piezotronic effect is enriched by above 360% under 0.3% applied strain at a low chamber temperature. This type of behavior is caused by the increased essential piezocharges at the interface/surface, which results from the less screening effect of the reduced charge carriers in the GaN thin film. To support this behavior, we investigate the piezophototronic effect in a GaN thin film at various temperatures under different strains. The study results will provide an in-depth understanding of the piezotronic and piezo-photonic effects and pave the way for forthcoming device applications in various fields, including human–machine interface, health monitoring, artificial intelligence, and surgical robotic operations. The temperature dependence of the piezotronic and piezophototronic effects in flexible GaN thin films were studied in diverse temperatures (225 K to 325 K) and with applied strains (0.0–0.3%). The piezotronic effect is boosted by over 360% at low temperature due to the enhanced efficiency of piezocharges. This behavior is due to reduced screening effect by decreased carrier generation in the flexible GaN thin film at 225 K. • Flexible GaN thin film device fabricated via a double transfer method. • Demonstrated the temperature dependence of the piezotronic and piezophototronic effects in GaN thin film. • Reduced screening effect by decreased carrier generation in the GaN thin film. • The piezotronic effect is boosted by over 360% at the low temperature of 225 K.