Optical and structural properties of CVD-grown single crystal SiO2 using optically detected XAS

Using a new method of low-temperature CVD preparation, very high quality single-crystal quartz can be grown at rates of up to 3 μm h−1. By employing synchrotron radiation methods, the optical and structural properties of these crystals can be interlinked and they are compared with those of high quality hydrothermally grown material. The luminescence excitation spectra, which are very sensitive to the quality of the material, are assessed for both band edge (excitonic) and core level Si L-edge excitations. For the most part, the optical and structural properties of the two types of sample are indistinguishable, verifying the high quality of the material grown by the new method. The only source of difference arises from a weak red luminescence band, thought to originate from NBOHC defects: in CVD material, the L-edges derived from this band reveal some degree of local lattice disorder.