Effects of low temperature buffer layer on all-sputtered epitaxial GaN/AlN film on Si (111) substrate

The effect of an Al buffer layer on the growth of AlN on a Si (111) substrate was investigated to develop an all-sputtered GaN film on a Si (111) template substrate. The X-ray diffraction method revealed an obvious improvement in the crystallinity of an AlN layer on the initial layer. At the interface structure, AlN film without the Al buffer layer exhibited surface nitridation of the Si surface, which degraded the AlN crystal growth. After investigating various growth conditions such as substrate temperature and layer thickness, we achieved the all-sputtered epitaxial growth of a GaN/AlN/Si substrate. The substrate temperature was below 650 degrees C, and the total thickness was less than 200 nm, which is beneficial as regards the cost efficiency of the template substrate for nitride semiconductors.