In-situ control of molecular beam epitaxial growth by spectral reflectivity analysis

•In-situ spectral reflectivity control of MBE of complex heterostructures.•Automation of thermal desorption of native oxide layers on GaAs substrates.•Demonstration of closed-loop growth control of terahertz quantum-cascade lasers.•Illustration of automated growth control of exciton polariton microcavities.•Presentation of in-situ growth control benefits over a time span of eight years. The epitaxial growth of complex heterostructures requires in-situ techniques for detection and control of the growth parameters. In-situ continuous spectral reflectivity measurements are used during molecular beam epitaxial growth to measure the substrate temperature and achieve close growth control on complex structures such as quantum-cascade lasers and microcavities. The corresponding utilized modes of operations are illustrated in detail and are found to enhance the reproducibility and precision of complex growth runs.