Siam Physics Congress 2015

Micro-structural Investigation of InGaAsN Lattice-matched Films Grown on Off-angle Ge (001) Substrates by MOVPE

21 May 2015, 13:00

3h 30m

Board: MNA-02

Poster presentation Material Physics, Nanoscale Physics and Nanotechnology Poster-3

Speaker

Mrs Pornsiri Wanarattikan (Department of Physics, Faculty of Science, King Mongkut’s University of Technology Thonburi, Bangkok, THAILAND 10140)

Description

In this work, the InGaAsN lattice-matched films were grown on off-angle Ge (001) substrates with inclined surfaces of 4$^{\circ}$ and 6$^{\circ}$ towards the [1 1 0] direction. All the samples were grown by metalorganic vapor phase epitaxy (MOVPE) using low temperature (550 $^{\circ}$C) GaAs buffer layer. To compare the InGaAsN film on on-axis Ge (001) substrate, micro-structural properties of the films on off-angle Ge (001) substrates were investigated by high-resolution X-ray diffraction (HRXRD), Raman scattering, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Since, InGaAsN with about 1-eV bandgap and lattice-matching to Ge is a candidate component material for the InGaP(N)/InGaAs/ InGaAsN/Ge four-junction-structure solar cells. HRXRD 2$\theta$/$\omega$ (004) results showed the Pendellösung fringes which clearly indicate a flat interface and a smooth surface for the InGaAsN films on off-angle Ge substrates. Furthermore, the smooth surface with low RMS roughness was obviously observed by AFM. Cross-sectional dark-field TEM images showed the GaAs buffer layer with a few anti-phase domains (APDs) at the GaAs/Ge interface. And then, APDs-free InGaAsN layer was observed on the off-angle Ge substrates. On the other hand, both the InGaAsN films and the GaAs buffer layers on on-axis Ge substrates demonstrated a high density of anti-phase boundaries. Our results indicate that high structural quality InGaAsN lattice-macthed films were successfully grown on the off-angle Ge (001) substrates.