Understanding surface reconstructions is an important aspect of controlling the structure of epitaxially grown III-V compound semiconductors. Ternary alloys such as InGaAs are important components of many electronic and optical devices and a parameter that is critical to the growth of these high quality devices is the presence of abrupt heterointerfaces.
As the final microstructures impact the performance of optoelectronic devices, it is important to understand why and under what conditions the reconstructions that initiate these structures form. Understanding the conditions under which these reconstruction domains form, and controlling their shape and size could provide another reliable method of forming spontaneous nanoscale assemblies.
The ultimate goal of my research is to develop a quantitative understanding of the connection between surface reconstructions on
In0.81Ga0.19As/InP and film thickness, surface energy, growth conditions, and surface morphology. The individual objectives of this work are to:
(1) Understand under which conditions multiple surface reconstructions coexist and the role of thermodynamics.
(2) Examine how growth conditions and material properties influence the surface reconstructions that appear for In0.81Ga0.19As ternary alloys.
(3) Look at the relationship between surface reconstructions and film morphology.
The combination of scanning tunneling microscopy (STM) and molecular beam epitaxy (MBE) growth is a necessary component of this research because the experimentation tools available on the MBE system allows for the examination of the surface structure during and after growth via reflection high energy electron diffraction (RHEED). The availability of an in vacuo STM allows the observation of the surface reconstructions prior to the formation of an oxide layer. Combining these two techniques allows for a better understanding between the growth procedure of the sample and the presence of surface reconstructions.
Ph.D.
Materials Science and Engineering
University of Michigan, Horace H. Rackham School of Graduate Studies
http://deepblue.lib.umich.edu/bitstream/2027.42/64755/1/leesears_1.pdf