In situ optical diagnostics of growing surfaces in the process of nanoheterostructure fabrication

It is demonstrated that in situ reflectance and reflectance-anisotropy measurements can be used as efficient real-time monitoring tools for all stages of the growth of heterostructures with ultrathin (few-monolayer) GaAs and AlAs layers. Changes in the layer composition at normal GaAs/AlAs interfaces in the active region of resonant-tunneling diode structures are detected with a thickness resolution on the order of one monolayer. Resonant-tunneling diodes with a peak-to-valley ratio of 3.3 and peak current density of 6.6 $\times$ 10$^4$ А/cm$^2$ are fabricated.