Formation of planar waveguides by implantation of O into cubic silicon carbide

This paper describes the formation of cubic silicon carbide planar waveguides which use a region implanted with high doses of oxygen as the guiding layer. The material used for these experiments is cubic silicon carbide grown on-axis on {001} CZ silicon substrates. Oxygen implants were either conducted at 200 kV for singly charged ions (O+) or 400 kV for molecular O-2(+) species. The results from the two types of implant are indistinguishable. To look at how the microstructure of the sample was influenced by implantation temperature a dose of 1.4 x 10(18) cm(-2) +/-10% was implanted into samples at temperatures ranging from approximate to 170 degreesC to 600 degreesC. It was found that implanting below 200 degreesC gives an amorphous layer, while at 600 degreesC the damage is comparable with the quality of the original single crystal starting material. The upper oxide/surface interface also sharpens with increasing temperature. The dose dependence of the microstructure was also examined. Doses ranging from 1 x 10(17) to 1.8 x 10(18) O cm(-2) were implanted while the wafer was maintained at 600 degreesC using a heated sample stage. At the lower doses less than or equal to8 x 10(17) O cm(-2) carbon and silicon self-interstitials are produced by the dissociation of the silicon carbide host lattice, in a manner analogous to that observed for silicon implanted silicon carbide. At higher doses, greater than or equal to1.4 x 10(18) O cm(-2) chemical effects predominate and the growing SiO2 layer causes the migration of the excess silicon and carbon interstitials towards the interfaces of the synthesized region. Increasing the implanted dose beyond 1.4 x 10(18) O cm(-2) results in a significant increase in the level of damage in the surface region. The results also show that for doses of 1.4 x 10(18) O cm(-2) and greater, a layer of SiO2 is formed at the peak of the implanted distribution.