Volatile metallo-organic precursors for depositing inorganic electronic materials

these materials are highly refractory and their conventional synthesis entails high temperatures, a highly undesirable feature. In particular the need to deposit thin films of multilayer devices posed a major problem for materials scientists. Whilst molecular beam epitaxy (MBE) is probably the ultimate technique for the controlled epitaxial deposition of very thin multilayers (10-100 A) under UHV conditions for research purposes, there is little doubt that metallo-organic chemical vapour deposition (MOCVD) has the advantage for rapid deposition covering large areas of substrate. The essence of the MOCVD process is the therrnolysis of volatile molecular precursors containing the requisite elements to deposit the desired compound (or element) on a suitable substrate at a convenient temperature. Thus a suitable precursor needs to be sufficiently stable to generate a substantial vapour pressure (e.g. 10 Torr) at a moderate temperature (e.g. 20-SOOC) and yet break down cleanly at a higher temperature. Photolytic decomposrtion is an alternative method of breakdown of the metallo-organic precursor. An added requirement in many cases is extremely high purity and from the industrial point of view non-toxic non-hazardous compounds are preferred. In recent years inorganic chemists have responded to the challenge of synthesizing suitable metallo-organic molecular precursors both by improving on the synthesis and purification of some