Influence of hydrogen on losses in silicon oxynitride planar optical waveguides

Abstract

We have examined the influence of bonded hydrogen on the losses in silicon oxynitride (SiON) planar optical waveguides on silicon substrates having a silicon dioxide buffer layer. In the SiON layer grown by plasma enhanced chemical vapour deposition, hydrogen was mainly bonded to silicon as evidenced by strong absorption at 2160 cm −1 . The concentration of bonded hydrogen was reduced from 1.2 × 10 22 cm −3 to 5 × 10 21 cm −3 as the substrate temperature was raised from 100 to 300 • C. The corresponding change in the loss was from 1.5 to 1.2 dB cm −1 at 632.8 nm.

Silicon nanocluster-sensitized emission from erbium: The role of stress in the formation of silicon nanoclusters

“…[10][11][12] Under thermal treatment, the film shrinks due to removal of the hydrogen incorporated into the film during the deposition process. 10,[13][14][15] Conventional silane-based PECVD of silicon dioxide exploits the plasma dissociation of silane ͑SiH 4 ͒ and nitrous oxide ͑N 2 O͒ to form silicon and oxygen reactive species ͑ions and radicals͒ that react on the substrate surface to produce films of SiO 2 . By controlling the flow rates of the precursor gases, the film stoichiometry is continuously variable over a wide range of compositions.…”

Plasma-enhanced chemical vapor deposition of low- loss as-grown germanosilicate layers for optical waveguides

“…In particular, loss at A=1.55 jim is known to be caused mainly by N-H and 0-H bonds incorporated into the film matrix while loss at 632.8 nm is mainly due to scattering mechanisms. 7 The reported values for propagation losses range between 3.5-10 at A=632.8 nm and are larger than 2 dB/cm at ,\=1.55 ,am,8 although not being analyzed systematically. To reduce the mentioned loss values, it is common practice to anneal the as-grown layers at temperatures as high as 1 100 °C for prolonged times .'…”

Low-loss as-grown germanosilicate layers for optical waveguides

“…4 As-deposited SiO x :Ge optical waveguides grown with these methods all share the shortcomings of having relatively large propagation losses at wavelengths of 632.8 nm and 1.55 m. In particular, loss at ϭ1.55 m is known to be caused mainly by N-H and O-H bonds incorporated into the film matrix, while loss at 632.8 nm is due mainly to scattering mechanisms. 7 Although there is no systematic study of propagation loss in germanosilicate planar waveguides, the reported values range between 3.5 and 10 dB/cm 1,2 at ϭ632.8 nm and are larger than 2 dB/cm at ϭ1.55 m. 8 To reduce the loss, it is common practice to anneal the as-grown layers at temperatures as high as 1100°C for prolonged times. 1,9 Recently, Zhang et al 9 reported CVD-grown germanosilicate planar waveguides with propagation losses of about 2 and 1 dB/cm at wavelengths of 632.8 and 1550 nm, respectively.…”