Growth of self-assembled and position-controlled InN nanowires on Si (1 1 1) by molecular beam epitaxy

This work presents a systematic growth study of self-assembled and position-controlled InN nanowires (NWs) on Si (111) substrates by plasma-assisted molecular beam epitaxy without using a buffer layer. By variation of the substrate temperature, the III/V flux ratio, and the growth time, optimal parameters for self-assembled and position-controlled NW growth are found and compared. This leads to a fundamental understanding of the underlying growth mechanism for InN NW formation. Scanning transmission electron microscopy measurements of a self-assembled InN NW show a wurtzite crystal structure with a hexagonal cross-section and flat lateral facets covered by an approximately 5 nm thick indium oxide shell. In addition, Kelvin probe force microscopy measurements indicate the existence of both lattice polarities in case of self-assembled InN NWs.