Metalorganic vapour phase epitaxy (MOVPE) of III/V-semiconductor heterostructures using alternative precursor molecules: new developments

Abstract

The standardly used source molecules in the metalorganic vapour phase epitaxy (MOVPE) of III/V-semiconductor heterostructures (trialkyl group(III)-compounds and group(V)-hydrides) have severe drawbacks. The trialkyl group(III)-compounds are pyrophoric and the group(V)-hydrides are highly toxic substances. These properties lead to problems of the MOVPE process with respect to safety concerns as well as crystal purity (incorporation of O and C especially for Al-containing epitaxial layers). In this work, we describe new developments of the interdisciplinary research for alternative precursor molecules. The principle ways for changing the molecular structure of alternative group(III)- as well as group(V)-compounds are discussed in order to overcome the above mentioned problems. Special emphasis is put on the class of the hydride group(III) amine adducts, which are in particular suitable in combination with less toxic group(V)-compounds. MOVPE growth experiments are reported for heterostructures in the GaAs/(AlGa)As material system. The applicability of the alternative precursors is established by studying the structural, electrical and optical properties of GaAs, (AlGa)As bulk layers as well as of single and multi quantum well heterostructures by high-resolution x-ray diffraction, temperature-dependent Hall as well as photoluminescence investigations.