Reference Module in Materials Science and Materials Engineering || Organometallic Source Materials for III–V Epitaxy

摘要： Compound semiconductors composed from elements of the IIIrd and Vth column of the periodic system find still increasing applications in modern electronic and optoelectronic devices. Their functionality can be easily tailored by synthesizing complex multicomponent epitaxial structures. A number of deposition techniques for such structures utilize organometallic precursors because of their excellent properties in gas phase transport and deposition controllability. The most important is metal organic vapor phase epitaxy (MOVPE), sometimes also called by the more generic term metal organic chemical vapor deposition (MOCVD). MOVPE operates at pressures between 200 and 105 Pa and typically involves vapor phase mixtures of a group III organometallic and a group V hydride. Other methods like chemical beam epitaxy (CBE) have been strongly investigated in recent years. This is a high vacuum technique (ca. 10–4 Pa) which utilizes a group III organometallic and a pre-cracked group V hydride. However, it became obvious that CBE could not fulfill the expectations of the method which attempted to combine the advantages of MOVPE and molecular beam epitaxy. Hence, it is only of minor importance today. Today, MOVPE is by far the most important epitaxial method for the deposition of compound semiconductors and respective heterostructures, being widely utilized in the large scale commercial production of III–V devices, such as light emitting diodes (LEDs), laser diodes, field effect transistors (FETs), hetero bipolar transistors (HBTs) and solar cells, particularly since GaN-based LEDs are starting to revolutionize our lighting technology by the use of highly efficient white LEDs (solid-state lighting). MOVPE has the advantages of large area growth, precise control of film thickness, and doping and superior conformal step coverage of small surface features. In this article, the organometallic precursors as key elements of these techniques will be discussed with respect to their synthesis, chemical and physical properties and their applications in the epitaxial growth of III–V compound semiconductors.