Molecular beam epitaxy/atomic layer epitaxy growth processes of widebandgap II-VI compounds: Characterization of surface stoichiometry by reflection highenergy electron diffraction J. Vac. Sci. Technol. A 8, 997 (1990); 10.1116/1.576910 Lightenhanced molecularbeam epitaxial growth in II-VI and III-V compound semiconductorsThe II-VI compounds are desirable for integrated optics due to their high electro-optic coefficients, wide transparency range from the visible to beyond 10 p.m, and the continuously adjustable refractive index offered by their ternary alloys. Films of waveguide thickness (1/2-2 p.m) were grown here by evaporation, under ultrahigh vacuum, of the constituent elements (Zn, Cd, Se, Te) from separately liquid-nitrogen-shrouded graphite Knudsen cells onto temperature-controlled chemomechanically polished single-crystal substrates. A quartz-crystal deposition monitor operating at the growth temperature was used in a novel way to determine the group-VI/II impingement rate ratio which would produce stoichiometric films, by measuring deposition rate as a function of the impingement rate ratio. Dissociative reevaporation of growing films sets an upper limit to growth temperature; I p.m/h reevaporation rates were calculated to be reached at 4OO'C for CdTe, 470'C for ZnTe and CdSe, and 570'C for ZnSe. At impingement rates corresponding to about 1 p.mlh, ZnSe ceased to deposit at 125'C below that point and the other three compounds at 50'C below that point. Over a 50'C range below the cessation of deposition, epitaxy was obtained for all II-VI compounds, as determined by in situ LEED. Film surface topography was examined by Nomarski differential-interference-contrast microscopy. Crystallographic quality depended slightly and surface smoothness depended very strongly on substrate orientation in the following decreasing order of quality: (1) GaAs(100); (2) GaAs(IIO); (3) CdS(OOOI), CdSe(OOOI). On GaAs, ZnTe and Zn(SeTe) films were much smoother than ZnSe films, I-p.m-thick films being smooth to tens of angstroms.The following system is recommended for integrated optics: ZnTe waveguide on Zn(SeTe) to optically isolate the waveguide from the high-index substrate, InAs(lOO) for 0.6% lattice constant mismatch.

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Smallscale highstrength silicon carbide fibers fabricated from thin films produced by plasmaenhanced chemical vapor deposition

The chemomechanical polishing of the “A” or cadmium‐rich face of cadmium sulfide has been accomplished. The etchant contained 90 mliters nitric acid, 300 mliters precipitated silica, and 10g aluminum chloride per 1000 mliters water. Best results were obtained using a poromeric polishing disk with 370 g/cm2 work pressure at 240 rpm polishing wheel speed. Surfaces were completely featureless when viewed by Nomarski and Michelson interference microscopy at 155 and 400X, and gave good LEED patterns after brief heat‐cleaning under vacuum.

Das mechanochemische Polieren der Cd‐reichen Fläche von CdS wird beschrieben.