TEM investigation of lattice-matched In0.53Ga0.47 as layers grown on InP by low-pressure metalorganic vapor-phase epitaxy

Abstract

High-quality defect-free In0.53Ga0.47 As thin film layers lattice matched to InP are important materials for the efficient operation of many optoelectronic devices used in long wavelength communication systems. The presence of defects in these devices is known to have a marked effect on their performance and long-term reliability. The In0.53Ga0.47 As layers reported here were grown by a low-pressure metalorganic vapor phase epitaxy method using tertiarybutylarsine as the As precursor; the layers were found to have high mobility and low background carrier concentrations. The aim of the present work is to investigate the microstructure, ordering, and degree of lattice misfit between the epitaxial In0.53Ga0.47 As layer and the InP using cross-sectional TEM (XTEM) and convergent beam electron diffraction (CBED) methods.A bright-field TEM image (Philips EM400T, 120 keV) taken in the cross-sectional view shows the In0.53Ga0.47As layer, a thin InP buffer layer (≈0.05μm), and the InP (Fe-doped) substrate (Figure 1). The dark cluster-like regions in the InP substrate are Fe-rich (confirmed by EDX).