Highly c-axis-oriented one-inch square freestanding GaN grown by hydride vapor-phase epitaxy using an AlN deposited on Si

In this letter, we report on the growth and the properties of freestanding GaN substrates. Large areas of one-inch square with a thickness of 0.5 mm w ere grown by the hydride vapor-phase epitaxy (HVPE) method after a thick fi lm of GaN was grown on an AlN buffer layer deposited on a sacrificial Si su bstrate which was subsequently chemically removed. The GaN substrate showed intensified X-ray diffraction from the (00.2) and the (00.4) planes, and t he full width at half maximum of the double-crystal X-ray diffraction curve was as large as 4.2 degrees. The photoluminescence spectra measured at 10 K and at 300 K exhibited a sharp and strong excitonic emission without deep -level emission. They also showed n-type conduction with an electron concen tration of similar to 1x10(18) cm(-3) and a Hall mobility of 50 cm(2)/Vsec. The highly c-axis oriented large-area freestanding GaN prepared using a Si sacrificial substrate by HVPE through this work can be used for homoepitax ial growth of GaN-based optoelectronic devices.