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Transparent and conducting SnO 2 thin film has been produced on quartz substrate using rapid thermal oxidation of pure Sn in air at different oxidation temperature and oxidation time. The transmittance T in the visible and NIR was investigated, the allowed direct energy gap was determined to be 3.18 eV at optimum condition of 600° and 90 s. The dependence of the resistivity on the film thickness and oxidation time has been studied. The optimum thickness of high transmittance and lowest resistivity is about 150 nm for SnO 2 were ρ = 2 × 10-2Ω cm and T = 88%.

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Novel far-infrared optically detected cyclotron resonance (FIR-ODCR) techniques are used to investigate GaAs epilayers and t h e resuits are compared with conventional cyclotron resonance performed at far-infrared frequencies and ODCR at microwave frequencies. The FIROOCR technique shows remarkable resolution and sensitivity and has been applied to investigations of t h e electronic structure of low-dimensional systems. In particular. cyclotron resonance has been optically detected in a GaAsIGaAIAs multiple quantum well ( M a w ) sample and compared with ODCR results performed at microwave frequency. Multi-single quantum wells (MSOW) in an MBE GaAsIGaAIAs structure with different well thicknesses have also been investigated, and by detecting cyclotron resonance via the.FlR-induced changes in the luminescence of the separate wells, the power of the technique to investigate the cyclotron resonance mass versus well thickness in a single sample has been demonstrated. Finally. t h e experimentally determined values of effective mass for different well widths are compared with the theoretical results, showing good agreement.