Structure and photoluminescence of Ge nanoclusters embedded in GeO _x films deposited using laser assistance at low temperature

Crystalline Ge nanocluster-embedded GeO_x films were deposited at low temperature using a laser-assisted plasma enhanced chemical-vapor deposition system. The structural and optical properties of the films deposited under various power densities of the assisting CO₂ laser beam were investigated. The size of the Ge nanoclusters decreased and the number density of the Ge nanoclusters increased with an increase in the laser power used in the film deposition. The Ge nanoclusters crystallization was improved with an increase in the assisting laser power. The observed photoluminescence (PL) characteristics, including the spectral position, decay curve, and intensity of the emission bands, can be attributed to the quantum confinement effect. These experimental results verified that the PL emission originated from the recombination of electron-hole pairs in the Ge nanoclusters. Furthermore, the growth process of the Ge nanoclusters was qualitatively studied.