Effect of a por-Si Buffer Layer on the Structure and Morphology of Epitaxial InxGa1 – xN/Si(111) Heterostructures

Abstract

Integrated heterostructures exhibiting nanocolumnar morphology of the In_xGa_1 – xN/Si(111) film are grown on a single-crystal silicon substrate (c-Si(111)) and a substrate with a nanoporous buffer sublayer (por-Si) by molecular-beam epitaxy with the plasma activation of nitrogen. Using a complex of structural and microscopic methods of analysis, it is shown that the growth of In_xGa_1 – xN nanocolumns on a nanoporous buffer layer offers a number of advantages over growth on c-Si. The por-Si substrate predetermines the preferential orientation of the growth of In_xGa_1 – xN nanocolumns closer to the Si(111) orientation direction and makes it possible to produce In_xGa_1 – xN nanocolumns with a higher degree of crystallographic uniformity and with a nanocolumn lateral size of ~40 nm unified over the entire surface. The growth of In_xGa_1 – xN nanocolumns on a por-Si layer yields a decrease in the strain components ε_xx and ε_zz and in the density of edge and screw dislocations compared to the corresponding parameters for In_xGa_1 – xN nanocolumns grown on c-Si. The In_xGa_1 – xN nanocolumnar layer fabricated on por-Si exhibits a 20% higher charge-carrier concentration compared to the layer grown on c-Si as well as a higher intensity of the photoluminescence quantum yield (+25%).