Pressure dependence of the blue luminescence in Mg-doped GaN

We report the hydrostatic pressure dependence of the blue luminescence band observed at similar to 2.8 eV in heavily magnesium-doped GaN (GaN:Mg) epil ayers grown on sapphire by metalorganic chemical vapor deposition. Photolum inescence (PL) studies carried out up to 6 and 8 GPa, respectively, at room and low (10 K) temperature show that the pressure-induced energy shift of this PL band is similar to 26 meV/GPa. This blueshift is about 40% less tha n the shift observed for the band edge in GaN. A substantially smaller pres sure coefficient suggests that the 2.8 eV PL transition is associated with the recombination via deep centers. (C) 2000 American Institute of Physics. [S0003-6951(00)04442-9].