High Resistivity GaN Single Crystalline Substrates

High resistivity 104 -106 Ω cm (300 K) GaN single crystals were obtained by solution growth under high Ν2 pressure from melted Ga with 0.1-0.5at.% of Mg. Properties of these crystals are compared with properties of conductive crystals grown by a similar method from pure Ga melt. In • particular, it is shown that Mg-doped GaN crystals have better structural quality in terms of FWHM of X-ray rocking curve and low angle boundaries. Temperature dependence of electrical resistivity suggests hopping mechanism of conductivity. It is also shown that strain free GaN homoepitaxial layers can be grown on the Mg-doped GaN substrates. PACS numbers: 71.55.Eq, 72.80.Ey