Effects of deposition conditions and annealing process on the infrared optical properties of diamond films grown by MPCVD

The effects of deposition conditions and annealing process on the optical properties of diamond films on silicon substrate grown by MPCVD method are investigated by infrared spectroscopic ellipsometry (2.5-12.5mum). Results indicate that the low nucleation temperature will be in favor of decreasing the infrared absorption at 3.5mum. The refractive index n of diamond films deposited under higher growth temperature will fluctuate weakly. After annealing in N-2 atmosphere an obvious improvement of the infrared optical properties is also found. After annealing the value of k was about 10(-12)similar to10(-15). However, for non-annealed diamond film, the value of k was about 10(-3)similar to10(-14). After annealing the refractive index n increased and was close to that of single crystal Type IIa natural diamond.