The study is dealing with short-time high power microwave treatment of metal-semiconductor structures on gallium-arsenide. We used epitaxial n-n++ GaAs structures and standard metalization procedure as a sample. Quality factor n, barrier height of Schottky barrier ϕΒ, eV, and reverse current Ir were measured using voltage-current curves of the test structures . Curvature of the structure had been determined using precision X-ray diffractometry. [1]figureFig.1 Dose dependence of the mechanical and electric parameters of the Schottky structure after microwave treatment. There are two well-observable stages in the curvature dependency: initial relaxation stage (first five second of treatment) and final relaxation stage. This final stage leads to R=∞, i.e. full relaxation of intrinsic thermoelastic stress, but in the same time it doesn't improve quality factor n or reverse current Ir. As one can see from fig.1., the first stage also was accompanied with tremendous improvement of the Schottky barrier quality with an increasing of barrier height and decreasing of reverse current. In the initial stage change of reverse radius of curvature agrees with exponential approximation: 1/R=0.045+0.121*exp(-t/0.88). So short characteristic time (0.88 s) and room temperature of the process suggest conservative mechanism of plastic deformation, i.e. stress relaxation through a dislocation movement without capturing or emitting of point defects. It is a strict evidence for acoustic waves as a main nonthermal affecting factor of the microwave treatment, since only this way of energy dissipation could induce fast dislocation movement in a crystal lattice, because of a hyper-sound absorption in dislocation kinks. These acoustic oscillations with short wavelength are generated in the skin layer of the Schottky barrier in the ultra-high frequency electromagnetic field by common pondermotoric effect being enhanced with piezoelectricity of the material in the presence of thin metalization layer. Described acoustic stimulated effect is of a great importance for power microwave nano-devices reliability.