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Hla Group Labs
Smith Group Labs:
The Smith lab is concerned with the growth and analysis of new and novel electronic and magnetic materials. A major part of the lab is the molecular beam epitaxy-scanning tunneling microscopy (MBE-STM) system. With the MBE-STM, it is possible to deposit epitaxial thin films onto substrates in the MBE chamber, then transfer those samples to the STM in the adjoining analysis chamber, without exposing the samples to air. It is therefore possible with this system to investigate the atomic-scale structure of a sample surface in its pristine, clean state, just after having been deposited or “grown” in the MBE. We can therefore avoid many sample cleaning steps which are often necessary without such an adjoined facility.
Currently the MBE-STM is configured for the study of nitrides, including GaN, but also other novel materials such as MnN and CrN (transition metal nitrides). The MBE system utilizes thermal “effusion cells” as metal evaporation sources and a radio frequency (rf) plasma source for N. The STM is capable of imaging samples with very high spatial resolution – down to 0.01 Ĺ in the vertical direction. It is therefore possible to measure surface structures having very small corrugations. The STM is also used to obtain magnetic (spin-polarized) information about samples by means of spin-polarized STM (SP-STM). A picture of the system is shown below.
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