Atomic layer epitaxy. Atomic layer epitaxy of 3-5 compound semiconductors by thermal and laser-assisted metalorganic chemical vapor deposition

Atomic Layer Epitaxy (ALE) is a promising variation of conventional vapor phase epitaxy which achieves uniform growth of ultra-thin epitaxial layers by a self-limiting monolayer by monolayer deposition process. By developing a new regime of metalorganic chemical vapor deposition (MOCVD) growth, in which saturated surface reactions control the growth, it is possible to alternately deposit monolayers of column 3 and column 5 elements so that only one monolayer of the 3-5 compound semiconductor is deposited in every cycle of the deposition. In this thesis, ALE growth of single crystal GaAs, as well as AlAs and GaAs/AlGaAs heterostructures and devices is demonstrated. We have been able to grow extremely uniform ultra-thin epitaxial layers and quantum wells (QWs) with thickness variations of less than one monolayer per cm over an entire sample in an optimized reactor using ALE. The observed dependence of the growth rate on temperature and trimethylgallium flux is modeled by first order adsorption kinetics utilizing measured reaction rate constants. The low temperature photoluminescence (PL) of ALE grown GaAs QW's exhibit narrow line intrinsic luminescence with linewidths comparable to the best reported values by conventional MOCVD.