A laser diode made of a Group III nitride based compound semiconductor layers comprising a sapphire substrate; a multiple layer structure of a Group III nitride based compound semiconductors formed on said substrate, said multiple layer structure having a double heterojunction structure with an active layer arranged between layers  having a greater bandgap than the active layer, whereby the Group III nitride compositions of the multiple layer structure are defined by the general formula (AlxGa1-x)y In1-y N with 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1; wherein said sapphire substrate has a oriented plane which corresponds to face a of said substrate and which functions as a principal plane for crystal growth; said multiple layer structure is formed on said principal plane of said sapphire substrate either directly or in the presence of an intervening buffer layer; and mirror surfaces are formed by cleaving said multiple layer structure and said sapphire substrate in directions parallel to the direction which corresponds to the c axis of said sapphire substrate.

The improved laser diode is made of a gallium nitride base compound semiconductor ((AlxGa1-x)yIn1-yN; 0</=x</=1; 0</=y</=1) with a double heterojunction structure having the active layer held between layers having a greater band gap, the laser diode comprises mirror surfaces formed by cleaving said multi-layered coating and said sapphire substrate in directions parallel to &Lang&0001&Rang& (c axis) of said sapphire substrate. Further, in the improved process, only the intermediate zinc oxide (ZnO) layer is removed by wet etching with a ZnO-selective liquid etchant so as to form gaps between the sapphire substrate and the bottommost sub-layer of said semiconductor laser element layer; and said semiconductor laser element layer is cleaved with the aid of said gaps 20, with the resulting planes of cleavage being used as the mirror surfaces of the laser cavity.


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In previous studies about the synthesis of GaN 1D nanostructures and Ga2O3 only appeared as one of the components of Ga source. Herein, we have successfully synthesized bulk-quantity GaN nanoribbons on sapphire substrates, from the direct reaction of sputtered Ga2O3 thin films with flowing ammonia. Neither metal catalysts nor templates were used in this process. The detailed characterization of the synthesized ribbon-like 1D nanostructures revealed that they were single crystalline hexagonal wurtzite GaN.

Single crystalline GaN nanoribbons were synthesized through nitriding Ga2O3 thin films deposited on sapphire substrates by radio frequency magnetron sputtering. The component and structure of nanoribbons were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The flat and smooth ribbon-like nanostructures are high quality single crystalline hexagonal wurtzite GaN. The thickness and width-to-thickness ratio of the grown GaN nanoribbons are in the range of 8–15 nm and ∼5–10, respectively.


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γ-LiAlO2 and sapphire substrates have been employed to grow nonpolar Zn1−xMgxO films using metalorganic chemical vapor deposition. Zn1−xMgxO films with various Mg contents (0 ≤ x ≤ 0.113) are obtained by adjusting the partial pressure of the Mg metalorganic precursor in gas phase. Mg atoms incorporate within the films by means of substituting Zn. No segregated phase such as MgO or metal Mg is observed throughout the Zn1−xMgxO films. Structural characterization of the films indicates that γ-LiAlO2 is a superior substrate to sapphire  for the growth of the nonpolar Zn1−xMgxO films.

The epitaxial  Zn1−xMgxO films are successfully grown on the γ-LiAlO2 substrates with the epitaxial relationship of ZMO  LAO. On the other hand, the Zn1−xMgxO films with both  and  orientations are obtained on sapphire substrates although Zn1−xMgxO becomes dominant with increasing Mg content. In addition, room-temperature cathodoluminescence spectra of the epitaxial Zn1−xMgxO films show an obvious blue shift of the near-band-edge emission with increasing Mg content, demonstrating bandgap engineering in the epitaxial nonpolar Zn1−xMgxO films on the γ-LiAlO2 substrates.


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Pulling of shaped sapphire crystals using resistance heating implemented by means of heating elements in a “circular” or a “linear” growth arrangement is described. The growth equipment can be easily disassembled beacause the individual molybdenum dies are connected to a die-holding block with a diffusion Mo-Mo bonding having a reduced strength. Advantages of the individual processes are described and the influence of the die-top temperature upon the quality of pulled crystal shapes is mentioned.

Edge Defined film Fed Growth (EFG) SaphikonTM sapphire crystals have been grown and successfully processed into windows measuring 225 x 325 mm with a thickness of 5.6 mm. More than 40 windows have been completed and assembled into customer hardware and delivered. The polished and coated windows have exhibited average transmission >93% from 1 to 5 mm and wavefront measurements of <0.1 waves rms (@ 0.633 μm) over a 125 mm aperture. Optical measurement data are presented and aspects of the crystal growth and polishing processes are discussed.


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