Stacked structure of self‐organized cubic InN nano‐dots grown by molecular beam epitaxy

Abstract

A two‐stacked cubic (c‐) InN/c‐GaN nano‐scale dot structure is fabricated on a MgO(001) substrate by RF‐N2 molecular beam epitaxy and its microstructures are investigated by scanning transmission electron microscopy (STEM). The cubic lattice structure of InN dots is verified by STEM observations. It is implied that c‐InN dots formed on a smooth c‐GaN surface have the {111} facets. The c‐GaN cap layer has an uneven surface, which reflects the shape of the c‐InN dots embedded beneath the cap layer. InN selectively deposits in concave regions on the c‐GaN cap layer, which appear above in‐between positions of embedded dots. Thus, stacked c‐InN/c‐GaN dots do not tend to align vertically. These results open the possibility for multi‐stacking structures of c‐InN dots and their application to high‐performance optoelectronic devices based on the nitride semiconductors. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Self‐organized growth of cubic InN dot arrays on cubic GaN using MgO (001) vicinal substrates

“…This indicates that the three‐dimensional growth of c‐InN took place. Significant differences were not found in the pattern from those for c‐InN dots grown using the just substrates under similar conditions, which was previously reported in our publications .…”

“…This indicates that the three-dimensional growth of c-InN took place. Significant differences were not found in the pattern from those for c-InN dots grown using the just substrates under similar conditions, which was previously reported in our publications [5,6]. Figure 5a shows the corresponding AFM image, in which c-InN dots with an average height of about 10 nm are observed.…”

“…Similar structures are also observed for c‐GaN grown using Si (001) substrates . This is due to the existence of two orthogonal domains of c‐GaN: one domain is c‐GaN (001) of which the [110] direction is parallel to [110] of a substrate, while it is parallel to of the substrate in the other domain. The typical scale of the domain size is 300–500 nm, as shown in the image of a c‐GaN surface grown on a MgO (001) substrate taken by atomic force microscopy (AFM) in Fig.…”

“…Similar structures are also observed for c-GaN grown using Si (001) substrates [11]. This is due to the existence of two orthogonal domains of c-GaN: one domain is c-GaN (001) of which the [110] direction is parallel to [110] of a substrate, while it is parallel to [1][2][3][4][5][6][7][8][9][10] direction. MgO (001) on-axis (just) substrates were also used for comparison.…”

“…By using a combination of cubic phase nitride semiconductors, it is possible to extend the applicable wavelength range because various experimental and theoretical studies suggest that metastable cubic InN (c‐InN) has a smaller bandgap than conventional hexagonal InN . Previously, we reported the self‐organized growth of c‐InN nanoscale dots on cubic GaN (c‐GaN) layers using MgO (001) substrates by RF‐N 2 ‐plasma molecular beam epitaxy (RF‐MBE) . The c‐InN dots exhibited a tendency to align laterally along the 〈110〉 directions on the c‐GaN (001) surface.…”