In situ thickness monitoring and control for highly reproducible growth of distributed Bragg reflectors

A theoretical model was developed to simulate the apparent substrate temperature oscillation during the growth of Al/As/AlxGa1-xAs, x=O and 0.25 distributed Bragg reflectors (DBR) for 980-and 780-nm vertical cavity surface emitting lasers, respectively. The simulated data were then used for in situ monitoring and feedback control of layer thickness by a simple pyrometric interferometry technique to obtain a highly reproducible DBR. These measurements can be performed with continuous substrate rotation and without any growth interruption. The reproducibility of the center wavelength and full width at half-maximum of the reflectivity stop band with a variation of <±0.2% and <±0.4% for the AlAs/GaAs and AlAs/AlGaAs mirror stacks, respectively, were achieved. 12 refs., 5 figs