METALORGANIC CHEMICAL VAPOR DEPOSITION : EXAMPLES OF THE INFLUENCE OF PRECURSOR STRUCTURE ON FILM PROPERTIES

Abstract
The influence of precursor structure and reactivity on properties of compound semiconductors grown by metalorganic chemical vapor deposition (MOCVD) is discussed and illustrated with examples for growth of GaAs, ZnSe, and Al_xGa_1-xN. Gas-phase and surface reactions of organometallic arsenic compounds provide understanding of variation in carbon incorporation levels with precursor structure. Surface spectroscopy studies reveal the critical role of hydrogen-arsenic bonds in reducing carbon levels. MOCVD of ZnSe with different organoselenium compounds demonstrate that the growth rate behaves as expected from the Se-ligand bond strengths, but also that unexpected minor pathways can make a precursor unsuitable by causing increased carbon incorporation. Interactions between organometallic precursors mean that the structure of the precursors cannot be manipulated independently for the individual precursors, but must be considered in terms of the overall growth chemistry. The use of a single-source precursor, versus separate precursors for MOCVD of compound semiconductors is discussed and illustrated with data for the growth of AIN and GaN.