High Hole Mobility of GaSb Relaxed Epilayer Grown on GaAs Substrate by MOCVD through Interfacial Misfit Dislocations Array

Abstract

The structural property of GaSb epilayers grown on semi-insulator GaAs (001) substrate by metalorganic chemical vapor deposition (MOCVD) using Triethylgallium (TEGa) and trimethylantimony (TMSb), was investigated by variation of the Sb:Ga (V/III) ratio. An optimum V/III ratio of 1.4 was determined in our growth conditions. Using transmission electron microscopy (TEM), we found that there was an interfacial misfit dislocations (IMF) growth mode in our experiment, in which the large misfit strain between epilayer and substrate is relaxed by periodic 90 deg. IMF array at the hetero-epitaxial interface. The rms roughness of a 300 nm-thick GaSb layer is only 2.7 nm in a 10 μm×10 μm scan from atomic force microscopy (AFM) result. The best hole density and mobility of 300 nm GaSb epilayer are 5.27×10 6 cm −3 (1.20× 10 6 ) and 553 cm 2 ·V −1 ·s −1 (2340) at RT (77 K) from Hall measurement, respectively. These results indicate that the IMF growth mode can be used in MOCVD epitaxial technology similar to molecular beam epitaxy (MBE) technology to produce the thinner GaSb layer with low density of dislocations and other defects on GaAs substrate for the application of devices.