Mobilities similar in magnitude to bulk silicon mobilities may be realized in 1.4 to 1.6µ thick films on flame fusion magnesium aluminate spinel, for carrier concentrations greater than ≈2×1016 cm−3 (p‐type). The electrical properties of these films are not significantly altered by thermal oxidation at 1200° C for 1 hr. In this carrier concentration range the electrical characteristics are not highly dependent on the deposition rate within the limits investigated. For carrier concentrations between 5×1015 and 2×1016 cm−3 (p‐type) the “as deposited” film mobilities are near bulk values, but the mobilities are degraded by the thermal oxidation. In this doping range the electrical properties of the oxidized films are critically dependent on the deposition rate. The films deposited at the higher rates are altered less on oxidation than films deposited at the lower rates. Using a growth rate of 2 µ/min, a mobility of 300 cm2/V‐sec (≈80% of bulk) at Nnormala=4×1015 cm−3 may be realized in a film oxidized 1 hr at 1100°C. Below this carrier concentration the mobility of the oxidized films decreases sharply with decreasing carrier concentrations. Minority carrier lifetimes as high as 40 nsec have been realized in 4µ thick films of silicon on spinel. The carrier concentration as a function of temperature and mobility as a function of thickness of silicon on spinel have been measured.

Thin dielectric films of niobium oxide have been deposited on silicon and quartz substrates by pyrolysis of the niobium alcoholate normalNbfalse(OC2H5)5 normalat 450°C in an oxidizing ambient. Optical measurements have been made on these films in the spectral range 0.2–2.6 µm. Information on dispersion, fundamental absorption edge, and absorption coefficient (as related to photon energy) has been obtained. An electrical evaluation of the films has been made, including dielectric properties and MOS behavior.

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Stoichiometric magnesium aluminate spinel false(MgAl2O4false) single crystals grown by the flux, Czochralski, and Verneuil methods have been characterized for their dielectric and optical properties. Dielectric properties were determined from capacitance measurements in the frequency range 102–105 Hz. The dielectric constant and loss tangent of MgAl2O4 spinel crystals grown by the various methods are comparable. At 1 kc the MgAl2O4 spinel has a dielectric constant of 8.4 and a loss tangent of 10−4. Optical transmission and reflection measurements were made in the wavelength range uv to IR (0.2–40 µm). Optical characteristics of the MgAl2O4 crystals are highly dependent on the method of growth. Chromium‐doped MgAl2O4 spinel single crystals have also been grown by a flux technique. Optical emission and absorption characteristics of Cr+3 in flux‐grown MgAl2O4 spinel have been studied. The results are compared with those of Cr+3 in natural spinel and synthetic spinel crystals prepared by the Czochralski and Verneuil methods.