Implementation of a closed-loop growth scheme for AlAs-GaAs distributed Bragg reflector (DBR) structures using in situ pyrometric interferometry monitoring

We have investigated a closed-loop control system for molecular beam epitaxial growth of quarter-wavelength AlAs-GaAs distributed Bragg reflector (DBR) structures using in situ pyrometric interferometry. The quasi-sinusoidal PI data was being treated as an amplitude and phase modulated signal for control of layer thickness. Highly reproducible PI signals were obtained without the need of careful growth rate calibration. This technique can be useful in achieving reproducible growth of DBR structures, including vertical cavity surface emitting lasers.