[Application] Oxygen, silicon, germanium, carbon, or nitrogen is selectively implanted into a workpiece. The workpiece is annealed to incorporate the ions into the workpiece. A compound semiconductor is then formed on the workpiece. For example, gallium nitride may be formed on a silicon, silicon carbide, or sapphire workpiece. The width of the implanted regions can be configured to compensate for any shrinkage during annealing.