Currently, defects existing in materials and at the interface are the main bottlenecks limiting the manufacture of high-performance electron devices, especially semiconductor devices where the performance and reliability are affected by these defects. Therefore, high temperature annealing (HTA) is often applied to passivate defects, though it raises additional issues in the device fabrication process, such as heat budget and impurity diffusion. In this article, we propose a passivation technique induced by a supercritical fluid (SCF) treatment at relative low temperatures and test it for use in various devices. The SCF treatment is equipped with both high permeability and solubility to introduce reactive substances which act to passivate defects and further enhance device performance without altering the device material or making major changes to the fabrication process. The experimental results prove that this technique can be applied to the AlGaN-based ultraviolet C light-emitting diode to increase the band-to-band emission spectrum of 280 nm, as compared with the 360 nm emission spectrum of defects. The electrical characteristics of the GaN-based high electron mobility transistor including on/off currents, trans-conductance (Gm), and current collapse were also improved. Such a SCF treatment can also be applied to Si-based fin field effect transistors to increase the Gm and mobility because of reduction of defect concentration. This SCF treatment was also applied to a current-production heterojunction with intrinsic thin layer solar cell to improve the efficiency from 18.2% to 19.5%. Using this SCF treatment on InGaZnO thin film transistors results in effective suppression of the VTH shift, which proves the defects in the gate insulator have been eliminated. The SCF treatment has also been applied to a SnO2 gas sensor to increase the selectivity and endurance to humidity because of the passivation of vacancies. These all confirm that this SCF treatment’s passivation capability can be applied to various electron devices. In addition, this SCF treatment has the advantages of being performed at low-temperature in a non-destructive process in a batch treatment with high selectivity, which provides the semiconductor industry a method to solve the manufacturing bottleneck in advanced electron devices.