Selective epitaxial growth of AlN and GaN nanostructures on Si(111) by using NH_3 as nitrogen source

摘要

The very first stages of AlN and GaN epitaxial growth by molecular beam epitaxy on the Si(111) surface using NH_3 as nitrogen source are studied mainly using reflection high-energy electron diffraction and scanning tunnelling microscopy. This study is performed in order to find a way to selectively nucleate AlN and GaN on Si(111). Exposing the Si surface to NH_3 is sufficient even at very low pressure to provoke the formation of β-Si_3N_4-like zones at the surface. Such zones are stable under Ga deposition but are converted into AlN by Al deposition. Therefore, combining partial surface nitridation and Al deposition gives rise to the selective epitaxy of AlN clusters in the nitrided zones. Moreover, the subsequent exposure to NH_3 and Ga leads to the growth of GaN only in places where AlN has previously nucleated.