REAL-TIME IN-SITU THICKNESS CONTROL OF FABRY-PEROT CAVITIES IN MBE BY44 AND 88 WAVELENGTH ELLIPSOMETRY

We have demonstrated how to use the 44 wavelength ellipsometer for in- situ closed-loop feedback control of a molecular beam epitaxy in order to grow reproducible AlAs/GaAs Fabry-Perot cavities. Sample-to-sample reproducibility of the Fabry-Perot cavity mode position measured usin g normal incident reflection was better than 0.2% among six samples gr own at different times and different growth conditions. This shows tha t a reproducible control of AlAs/GaAs layer thickness is achievable us ing the 44 wavelength ellipsometer. The new ss wavelength ellipsometer includes UV wavelengths from 2770 to 4150 Angstrom. The closed-loop i n-situ control of Fabry-Perot cavity growth will be explained and the results from the two types of ellipsometers will be compared.