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A new method, high-vacuum electron-beam co-evaporation is used to prepare silicon nanocrystals (Si NCs) embedded in Al2O3 dielectric matrix in the form of thin films. Silicon and Al2O3 are co-evaporated by two electron guns at the same time at room temperature with the pressure below 1×10−5 Pa. After evaporation, annealing in N2 ambient at 500 and 800 °C for 1 h is performed. X-ray diffraction and atomic force microscopy are used to estimate the diameter of the Si NCs and check the morphology of the co-evaporation film respectively. X-ray photoelectron spectroscopy is used to investigate the chemical state of Si and Al in the as-prepared and annealed samples. Electrical properties of the Si NCs are investigated and resonant tunneling due to three dimensional quantum confinements is observed at room temperature. [Copyright &y& Elsevier]