MONOLAYER RESOLUTION CHARACTERIZATION BY VARIABLE ANGLE SPECTROSCOPIC ELLIPSOMETRY (VASE)

ELLIPSOMETRY USES POLARIZED LIGHT REFLECTANCE TO CHARACTERIZE SURFACES, INTERFACES, AND THIN FILMS. ELLIPSOMETRY HAS TRADITIONALLY BEEN DONE USING A FEW (USUALLY ONE) DISCRETE ANGLES OF INCIDENCE OF THE LIGHT BEAM WITH A SURFACE NORMAL, AND A FEW SELECTED WAVELENGTHS (FREQUENTLY ONLY 632.8 NM FROM A HENE LASER). RECENTLY IT WAS SHOWN (BY WOOLLAM AND COWORKERS) THAT USING VARIABLE ANGLE OF INCIDENCE SPECTROSCOPIC ELLIPSOMETRY THE SENSITIVITY CAN BE ENHANCED BY MORE THAN THREE ORDERS OF MAGNITUDE. THE USEFULNESS OF THIS TECHNIQUE FOR HETEROJUNCTION STRUCTURES WAS DEMONSTRATED. THE PURPOSE OF THIS CONTRACT IS THREEFOLD: TO DEVELOP VASE FOR MOCVD GROWN MULTILAYER SEMICONDUCTOR DIAGNOSTICS, TO ENHANCE THE DATA ACQUISITION SPEED BY A FACTOR OF TEN (THUS PERMITTING IN-SITU CAPABILITIES), AND TO DEVELOP THE CAPABILITY TO ANALYZE DATA FROM SEMICONDUCTOR SUPERLATTICES USING AN IBM AT COMPATIBLE COMPUTER.