Reusable nitride wafer, method of making, and use thereof

A method for re-using a used crystalline nitride wafer from which a layer has been removed, said used nitride wafer having a diameter greater than about 25 millimeters and a thickness between about 100 micrometers and about 10 millimeters, a substantially wurtzite structure, a first surface from which said layer was removed, said first surface having a root-mean-square surface roughness greater than about 10 nanometers measured over an area of 20 micrometers by 20 micrometers;

• and a second surface opposite said first surface and having a root-mean-square surface roughness less than about 10 micrometers measured over an area of at least 20 micrometers by 20 micrometers, said method comprising:
• preparing at least one of said first surface and said second surface for re-growth to form a planarized substrate;
• performing bulk crystal growth on said planarized substrate to form a regrown wafer;
• and
• preparing a regrowth surface on said regrown wafer to an epi-ready state, said regrowth surface having a surface threading dislocation density less than about 107 cm−2, a stacking-fault concentration below about 102 cm−1, and a symmetric x-ray rocking curve full width at half maximum (FWHM) less than about 100 arcsec, and a root-mean-square surface roughness less than about 0.5 nanometers measured over an area of 20 micrometers by 20 micrometers.