Microphotoluminescence and Microphotoreflectance Analyses of$hboxCO_2$Laser Rapid-Thermal-Annealed$hboxSiO_x$Surface With Buried Si Nanocrystals

The optical properties of a SiO
_x
film rapid-thermal-annealed (RTA) by CO
₂
laser are primarily investigated. The microphotoluminescence (mu-PL) and high-resolution transmission electron microscopy (HRTEM) analyses indicate that the precipitation of random-oriented Si nanocrystals can be initiated when laser intensity (P
_laser
) is larger than 4.5 kW/cm
²
. At P
_laser
of 6kW/cm
²
, the Si nanocrystal exhibits a largest diameter of 8 nm and a highest density of 4.5times10
¹⁶
cm
^-3
, which emits strong PL at 790-825 nm. The microphotoreflectance of the CO
₂
laser RTA SiO
_x
film reveals a volume density product dependent refractive index increasing from 1.57 to 1.87 as P
_laser
increases from 1.5 to 7.5 kW/cm
²
. Nonetheless, the laser ablation of the SiO
_x
film occurs with a linear ablation slope of 35 nm/kW/cm
²
at beyond 7.5 kW/cm
²
, which terminates the enlargement of Si nanocrystals, degrades the near-infrared PL, and slightly reduces the refractive index of the CO
₂
laser RTA SiO
_x
film