  We report on the non-destructive measurement of Young's modulus of thin-film
single crystal beta gallium oxide (beta-Ga2O3) out of its nanoscale mechanical
structures by measuring their fundamental mode resonance frequencies. From the
measurements, we extract Young's modulus in (100) plane, EY,(100) =
261.4+/-20.6 GPa, for beta-Ga2O3 nanoflakes synthesized by low-pressure
chemical vapor deposition (LPCVD), and Young's modulus in [010] direction,
EY,[010] = 245.8+/-9.2 GPa, for beta-Ga2O3 nanobelts mechanically cleaved from
bulk beta-Ga2O3 crystal grown by edge-defined film-fed growth (EFG) method. The
Young's moduli extracted directly on nanomechanical resonant device platforms
are comparable to theoretical values from first-principle calculations and
experimentally extracted values from bulk crystal. This study yields important
quantitative nanomechanical properties of beta-Ga2O3 crystals, and helps pave
the way for further engineering of beta-Ga2O3 micro/nanoelectromechanical
systems (M/NEMS) and transducers.
