REAL-TIME IN-SITU COMPOSITION CONTROL OF INGAAS LATTICE-MATCHED TO INP BY AN 88-WAVELENGTH ELLIPSOMETER

We have compiled the optical constants database for InxGa1-xAs which c overs the composition range from 0.51 to 0.55 and the temperature rang e from 40 to 525 degrees-C. The InP substrate temperature was monitore d by diffusive spectroscopy during the growth of the epitaxial layer. Ellipsometry was used to monitor the InxGa1-xAs composition over the e ntire temperature and composition range of the database. The compositi on monitored by ellipsometry is within 0.002 from the high resolution x-ray data with the exception of growth temperature at 440 degrees-C w hich is 0.005. We have also demonstrated the real time in situ feedbac k control of the InxGa1-xAs composition during epitaxial growth by usi ng ellipsometry. The absolute accuracy of the InxGa1-xAs composition f rom the controlled experiment is 0.002. We can use this database to gr ow thick InxGa1-xAs layers grown on the InP substrates and can also us e this as as in situ tool to fine tune the InxGa1-xAs composition befo re growth of the complicated structure.