A comparison of TMG with TEG for the growth of InxGa1-xAs

MOCVD growth of InxGa1-xAs from trimethylgallium (TMG), triethylgallium (TEG), trimethylindium (TMI) and arsine was studied over a wide range of growth conditions. It was found that the InxGa1-xAs strain with respect to InP is strongly influenced by the arsine concentration when grown with TEG and TMI. In contrast the InxGa1-xAs strain was independent of arsine concentration when grown with TMG and TMI. It was also observed that the growth rate of In Ga1-xAs is higher for TMG than for TEG with the same TMI and arsine flow. In addition an interaction between TEG and dimethylzinc (DMZ) was also observed. We show that MOCVD growth process involves many complex reactions and cannot be considered as a simple decomposition of each precursor. The interactions between precursors which takes place in the gas phase or on the growing surface, has to be considered. We have utilized the TEG/arsine interaction for the growth of strain compensated superlattices by modulating the arsine flow into the reactor chamber while keeping the TEG and TRI constant. Structures with up to 100 periods of 100 Angstrom of + 1% In0.6Ga0.4As and 200 Angstrom of -0.5% In0.5Ga0.5As were grown with excellent characteristics.