| Summary: | 碩士 === 國立交通大學 === 電子物理系 === 86 === Znse films were grown on quartzs and GaAs (100) substrates by cw CO2 laser with ion beam-assisted deposition. The films grown on quartz substrates were the zinc-blende polycrystalline structure with a strong preferred [111] orientation, even deposited on room teperature substrates.Without ion beam assistance, the film grown at a substrate temperature 150℃, a growth rate 6.4 A/sec had the best properties which the refractive index was 2, 5218, the extinction coefficient was 0.0016 at 700 nm and the peel strength was 11.44 mN. With ion beam assistance, the film grown at a ion beam voltage 200V, a ion beam current 15 mA was the best one whose refractive index was 2.536 close to single crystal ZnSe bulk 2.6540, extinction coefficient was 0.0010 and peel strength was 16.9 mN. From Raman measurements, the stress between the ZnSe film and the quartz substrate was 1.27×1013 dyn cm-2 We found that the properties of polycrystalline ZnSe films prepared by the system we used were better then those by the traditional thermal and electron beam evaporation.
When the substrate temperature was above 200℃, the ZnSe film grown on a GaAs (100) substrate became a single crystal. By the way, we found that the low energy ion beam could remove the oxide covering over the GaAs substrate surface. Raman measurements showed that the stress between the film grown at 400℃ and the Ga As (100) substrate was smallest and the film transmittance to 488 nm laser beam was highest. According to spatial correlation model of Raman scattering, the coherence length (L=16.5 nm) of the film grown at 350℃ was longest. PL of the film grown at 400℃ was gotten. The low temperature (T=20K) PL showed that the energy of the donor-bound exciton (I2) transition was 2.795 eV and the FWHM was 7.6 meV. From PL measurements at different temperatures, the linear temperature coefficient of I2 was-4.3×10-4 eV K-1 and the activation energy was 25 meV.
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