Surface Adsorption and Air Damping Behavior of β‐Ga2O3 Nanomechanical Resonators

Abstract Beta gallium oxide (β‐Ga 2 O 3 ) has emerged as a highly promising semiconductor material with an ultrawide bandgap ranging from 4.5 to 4.9 eV for future applications in power electronics, optoelectronics, as well as gas and ultraviolet (UV) radiation sensors. Here, surface adsorption and air damping behavior of doubly clamped β‐Ga 2 O 3 nanomechanical resonators are probed and systemically studied by measuring the resonance characteristics under different gas and pressure conditions. High responsivities of resonance to pressure are obtained by heating the devices up to 300 °C to induce an accelerated adsorption–desorption process. The initial surface conditions of the β‐Ga 2 O 3 thin film play important roles in affecting the resonant behavior. UV ozone treatment proves effective in altering the initial surface conditions of β‐Ga 2 O 3 nanosheets by eliminating physisorbed contaminants and filling oxygen vacancy defects residing on the surface, resulting in a consequential and discernible modification of the resonance behavior of β‐Ga 2 O 3 nanomechanical resonators. The surface adsorption and desorption processes in β‐Ga 2 O 3 demonstrate clear reversibility by exposing the UV treated β‐Ga 2 O 3 to air. This study attains first‐hand information on how the surface conditions of β‐Ga 2 O 3 affect its mechanical properties, and helps guide future development of transducers via β‐Ga 2 O 3 nanoelectromechanical systems (NEMS) for pressure sensing applications, especially in harsh environments.