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InGaN/GaN multi-quantum well (MQW) laser diodes (LDs) were grown on c-plane sapphire substrates using a multi-wafer MOCVD system. The threshold current for pulsed lasing was 1.6 A for a gain-guided laser diode with a stripe of 10 × 800 μm2. The threshold current density was 20.3 kA cm−2 and the threshold voltage was 16.5 V. The optical power ratio of transverse electric mode to transverse magnetic mode was found to be greater than 50. The characteristic temperature measured from the plot of threshold current versus measurement temperature was between 130 and 150K.
Cubic boron nitride films were prepared by helicon wave plasma CVD process on (100) Si. The film deposited under the intense impact of energetic ions is usually delaminated from the substrate after deposition. The delamination behavior of c-BN film was investigated with transmission electron microscopy. It is found that moisture in the air, surface roughness of the film and substrate, as well as severe compressive stresses in the film are the primary contributors to film delamination. An aqueous oxidation was verified by EDXS analysis, which generate local stress by volume expansion at the crack region in the c-BN layer.
The cross-sectional TEM micrograph of c-BN film in Fig. 1 shows that a very thin layer of h-BN is deposited before the c-BN layer starts to grow at an early stage of film growth. A columnar structured thin h-BN layer about 20 nm thickness at the interface is clearly separated from the c-BN layer in an aspect of microstructure.
Cubic boron nitride films were prepared by helicon wave plasma CVD process on (100) Si. The growth and delamination mechanism of c-BN film was investigated with FT-IR spectroscopy and transmission electron microscopy. The film deposited under the intense impact of energetic ions is usually delaminated from the substrate after deposition. It is found that moisture in the air, surface roughness of the film and substrate, as well as severe compressive stresses in the film are the primary contributors to film delamination. An aqueous oxidation was verified by EDXS analysis, which generate local stress by volume expansion at the crack region in the c-BN layer. From the experimental results and ??? observation a model for the delamination mechanism of c-BN film is suggested. Based on the delamination mechanism, several kinds of remedies such as post annealing and post N2 plasma treatment were carried out for improving the adhesion.
Cubic SiC thin films have been grown by supersonic jet epitaxy of single molecular precursors on Si(100), Si(111) and Separation by IMplanted OXygen (SIMOX) silicon on insulator (SOI) substrates at temperatures in the range 780 - 1000 °C. Real-time, in situ optical reflectivity was used to monitor the film growth. Films were characterized by ellipsometry, x-ray diffraction (XRD), and transmission electron microscopy (TEM). Monocrystalline, crack-free epitaxial cubic SiC thin films were successfully grown at 830 °C on carbonized Si(111) substrates using supersonic molecular jets of dimethylisopropylsilane, (CH3)2CHSiH(CH3)2, and diethylmethylsilane, (CH3CH2)2SiHCH3. Highly oriented cubic SiC thin films in the  direction were obtained on SIMOX(100) at 900 °C with dimethylisopropylsilane and on Si(100) at 1000 °C with diethylmethylsilane. A carbonized Si(100) surface was found to enhance SiC deposition from diethylmethylsilane at a growth temperature of 950 °C.
The epitaxial layers of AIN and GaN were grown on Si and Sapphire substrate at a relatively low temperature of around 500 °C using the process of reactive ion beam assisted deposition. The optimum ion beam energy for epitaxial growth of AIN and GaN films was found to be about 50 eV. Characterization of the epitaxial layers was carried out by GID (Grazing-Incidence x-ray Diffraction) and high resolution TEM observation. The orientational relations between epitaxial layer and substrate were determined through these analysis. Very thin amorphous layers were observed at the interfaces of bom AIN and GaN films grown on Si(111) substrate, whereas the films grown on Sapphire substrate has no amorphous layer. The amorphous layer may act as a buffer layer enabling the growth of the epitaxial layers of AIN and GaN by relaxing the misfit strain in the early growing stage.
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