X-ray excited optical luminescence (XEOL) measurements of Mg-doped
GaN were made using continuous spectrum of synchrotron radiation. The samples
were grown by metalorganic vapour phase epitaxy (MOVPE) on
α-Al
$_{2}$
O
$_{3}$
substrates. The
electrical activation of the Mg dopants by thermal annealing was detected in
the room-temperature XEOL spectra, but not in the ultraviolet light excitation
low-temperature photoluminescence (PL) spectra. The better results of the X-ray
excitation over the ultraviolet excitation PL is attributed to the larger
penetration depth of X-rays in heavily Mg-doped GaN. The activation of the Mg
dopants was confirmed using Hall measurements.
