Nd3+ photoluminescence study of Nd-doped Si-rich silica films obtained by reactive magnetron sputtering

Nd3+-doped silicon-rich silicon oxide (SRSO) thin films have been fabricated by reactive magnetron sputtering of a pure silica target topped with Nd2O3 chips. The concentration of Nd ions in the deposited layers is controlled by the number of Nd2O3 chips, whereas the incorporation of silicon excess is monitored by the hydrogen partial pressure, PH2, introduced in the Ar plasma, owing to the ability of hydrogen to reduce the oxygen released by the sputtering of the silica target. Photoluminescence (PL) experiments were made at room temperature using a nonresonant excitation line from an Ar laser. The influences of Nd3+ content and PH2 have been studied to optimize the Nd3+ emission. PL spectra reveal a two order of magnitude enhancement of the Nd3+ emission around both 0.9 and 1.1 μm, when Si nanoclusters (Si-nc) are formed in the same Nd3+-doped matrix. The dependence of the Nd3+ PL with PH2 and Nd concentration is indicative of the occurrence of an efficient energy transfer from the Si-nc to the rare earth ions. The radiative lifetime is also deduced and commented in the light of Nd3+-Si-nc coupling.