Growth of high quality N-polar AlN(0001¯) on Si(111) by plasma assisted molecular beam epitaxy

Abstract

High quality N-polar AlN epilayers were grown and characterized on Si(111) substrates by plasma assisted molecular beam epitaxy as a first step toward growth of N-polar nitrides on Si(111). Polarity inversion to N-face by an optimized predeposition of Al adatoms on the reconstructed 7×7 Si(111) surface was investigated. Al adatoms can saturate the dangling bonds of Si atoms, resulting in growth of AlN in (0001¯) direction on subsequent exposure to N2 plasma. N-polarity was confirmed by observing strong 3×3 and 6×6 reflection high-energy electron diffraction reconstructions, convergent beam electron diffraction imaging and KOH etching studies. The structural properties were investigated by x-ray diffraction measurements, cross section and plan-view TEM studies.