Fine characterization of MBE-grown super-multiperiod AlGaAs/GaAs superlattices designed for THz radiation sources

A comprehensive metrological analysis was conducted on doped and nondoped super-multiperiod superlattice (SMP SL) AlGaAs/GaAs structures comprising 400 periods, optimized to create tunable terahertz (THz) radiation sources operating at room temperature, involving high-resolution X-ray reflectometric and diffractometric studies on the synchrotron radiation source and a scanning transmission electron microscopy study. The SLs featured 15-20 distinct Bragg peaks with radiation energies of-6 and-8 keV. Some grown samples exhibited perturbations that could be attributed to small thickness/layer composition fluctuations, as demonstrated by the synchrotron radiation experiments and high-precision fitting. The AlGaAs barrier layer underwent a thorough characterization, wherein the additional modulation periods and amplitudes of the parameters of this layer were determined. This was achieved by using two independent methods of fine processing, namely high-resolution X-ray reflectometry and high-resolution X-ray diffractometry data. Deep X-ray reflectometry was used to check the validity of the data obtained. Based on these studies, the position of the samples and their rotation about the axis of the manipulator cause additional modulation during growth. Thus, the morphology and composition of A3B5 semiconductor heterostructures grown by molecular beam epitaxy are of perfect quality, with the design aiming to produce promising tunable, SMP SL-based THz radiation sources.