High pressure solution growth and physical properties of GaN crystals

The recent results in high pressure crystallization of GaN from the solutions of N in pure Ga and in its alloys with II group metals (Mg, Ca, Zn) are discussed. It is shown that high resistivity (10⁴ -10⁶ Ωcm) GaN crystals of improved structural quality can be grown from solutions containing Mg. The structural, electrical and optical properties properties of GaN crystals grown without and with the intentional doping are compared. It is also shown that atomically flat, thermally stable surfaces of GaN substrates can be obtained by mechanical and mechano-chemical polishing. Some most interesting results concerning homoepitaxial growth by MOCVD and MBE are reviewed