Controlling Defects and Doping in CVD Grown Diamond Epi-Layers

Homoepitaxial layers of diamond are grown with microwave plasma CVD that can be intrinsic, isotopically purified, boron doped, nitrogen doped or phosphorus doped based on the diamond device being fabricated. Applications include diamond electronics, diamond detectors, and NV center quantum sensors. The grown epi-layers are desired to be uniformly or controllably doped with minimal unwanted impurities/point defects and minimal dislocation defects in order to achieve best device performance.

This presentation will examine the importance of the preparation of the surface before CVD growth begins, understanding and control of uniformity of doping during growth, techniques to minimize unwanted impurities/point defects in the diamond, and minimization of new dislocation defects in epilayers. Particular techniques examined for their importance include mis-cut angle of the growth surface from the (100) crystal plane, removal of polishing damage before epi-layer growth, influence of surface roughness before CVD including use of chemical-mechanical polishing (CMP), growth conditions/parameters to influence step flow growth aspects of steps and terrace sizes, and uniformity of growth temperature through-out the substrate during growth as it affects stress and dislocation generation. Experimental techniques used to analyze grown epi-layers include microscopy, SIMS, cathodoluminescence, photoluminescence, and electrical properties. Both top growth surface and cut and prepared cross sections of the epi-layers are analyzed.