Network of vertically c-oriented prismatic InN nanowalls grown on c-GaN/sapphire template by chemical vapor deposition technique

Networks of vertically c-oriented prism shaped InN nanowalls, are grown on c-GaN/sapphire templates using a CVD technique, where pure indium and ammonia are used as metal and nitrogen precursors. A systematic study of the growth, structural and electronic properties of these samples shows a preferential growth of the islands along [11 (2) over bar0] and [0 0 0 1] directions leading to the formation of such a network structure, where the vertically [0 0 0 1] oriented tapered walls are laterally align along one of the three [11 (2) over bar0]directions. Inclined facets of these walls are identified as semipolar [11 (2) over bar2]-planes of wurtzite InN. Onset of absorption for these samples is observed to be higher than the band gap of InN suggesting a high background carrier concentration in this material. Study of the valence band edge through XPS indicates the formation of positive depletion regions below the surface of the side facets [(1122)-planes] of the walls. This is in contrast with the observation for c-plane InN epilayers, where electron accumulation is often reported below the top surface. (C) 2018 Elsevier B.V. All rights reserved