The influence of growth temperature and input V/III ratio on the initial nucleation and material properties of InN on GaN by MOCVD

摘要

The effects of growth temperature and V/III ratio on the InN initial nucleation of islands on the GaN (0001) surface were investigated. It is found that InN nuclei density increases with decreasing growth temperature between 375 and 525 ℃. At lower growth temperatures, InN thin films take the form of small and closely packed islands with diameters of less than 100 nm, whereas at elevated temperatures the InN islands can grow larger and well separated, approaching an equilibrium hexagonal shape due to enhanced surface diffusion of adatoms. At a given growth temperature of 500 ℃, a controllable density and size of separated InN islands can be achieved by adjusting the V/III ratio. The larger islands lead to fewer defects when they are coalesced. Comparatively, the electrical properties of the films grown under higher V/III ratio are improved.