Application of in situ reflectance monitoring to molecular beam epitaxy of vertical-cavity structures

We have used normal-incidence reflectance to monitor the growth of molecular beam epitaxial films. Least-squares fitting of the single-wavelength reflectance over regions of constant film growth rate and composition allowed the determination of growth rate and the complex refractive index of the film at the growth temperature. For AlInGaAs materials employed in a 1.32 μm reflectance modulator device, we found that layer thicknesses of approximately 500 A produced precise measurement of these parameters. A simple feedback control scheme based on these measurements was employed to control the wavelength of the room-temperature cavity mode resonance in these devices to approximately 0.2%.