High performance quartz

Recent experiments in the laboratory and under factory conditions and a reassessment of the literature aimed at developing techniques for preparing high-performance quartz, especially r-bar quartz for SAWS, radiation hard quartz, and low-channel and low-dislocation-density material, are reported. The r-bar material is found to be preferable for SAW wafers because the wafer is cut parallel to the growing face, resulting in greater homogeneity and increased yield. Procedures for Al impurity reduction to improve radiation resistance are described. Procedures for using SiO₂ glass with a very low Al content as nutrient are described. Etch channels are shown to be decorated dislocations, and measures which reduce dislocations (using dislocation free seeds, reducing particular inclusions, and minimizing seed-grown material lattice mismatch) are shown to be effective