| Abstract: |
Reflection high-energy electron diffraction (RHEED) oscillations are widely used in molecular beam epitaxy (MBE) as a technique to calibrate material growth rates. The growth rates are used to predict the composition of the following growth run. For many applications, the predicted composition uncertainties of a few percent are adequate, but some applications, like vertical cavity lasers (VCSELs) and distributed Bragg reflectors, demand greater accuracy. To improve our accuracy in determining the composition of our MBE-grown films, it is obvious we need to understand the uncertainties and limitations associated with RHEED as an MBE tool. In this experiment, we study several aspects of RHEED in our growth system, including the effects of beam positioning, substrate size, different growth rates, and 2x- versus 4x- reconstruction spot. Additionally, we examine "beat" phenomena and beam flux transients and their implications on composition. We also present a procedure which, when the uncertainties of the growth rates are estimated, determines the composition equation that gives the smallest mean square error. |
