Strain-induced polarization modulation at GaN/Ti interface for flexible thin-film sensor

Abstract

Abstract We have demonstrated an effective piezoelectric polarized interface modulation in a GaN/Ti Schottky structure and fabricated a flexible GaN-based sensor using a double-transfer method. Chemical etching of the Ni sacrificial layer successfully removes the temporary substrate without damaging the metal electrodes. The fabricated flexible GaN-based sensor, with top and bottom Ti metal Schottky contacts, exhibits a current on/off characteristic under external strain. Specifically, the current shows a 53.9% reduction under 2.3% tensile strain and a 67.8% enhancement under −2.3% compressive strain at a 5 V bias voltage. It was found that the light/dark current ratio in the GaN/Ti Schottky junction significantly increases near zero-bias voltage under 2.3% tensile strain, likely indicating an enhanced built-in piezoelectric polarized field at the interface. This work advances the study of flexible sensors based on wurtzite III–V nitrides for wearable electronics and optoelectronics.