The MOVPE growth of InN by a horizontal reactor is compared with that by a vertical reactor. The phase diagram does not almost depend on the reactor structure, but rather the parameters such as V/III ratio and the growth temperature. The growth rate of InN in the horizontal reactor significantly increases in comparison with the vertical reactor due to the reduction of the stagnant layer thickness, the increases in the source supply to the substrate surface and the high concentration of source gases by narrowing flow channel. For the horizontal reactor, the polycrystalline phase appeared in the case of the low carrier‐gas flow‐rate and disappeared for the high carrier‐gas flow‐rate. These data suggest that increasing the carrier gas flow rate can suppress the gas phase reactions. In the case of the horizontal reactor, InN can be obtained at temperatures as high as 625 °C, compared with the maximum growth temperature of 575 °C in the vertical reactor. But the growth rates significantly decrease above 600 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Photoluminescence (PL) spectrum of a naturally‐oxidized InN sample has been investigated. The PL‐peak wavelength locates at around 1.53 µm, which is by 250‐300 nm shorter than that of an intrinsic InN. In addition to this PL peak shift of the InN crystals (corresponding bandgap variation) their quality seems to be improved from the analysis of PL spectra. The naturally‐oxidized layer is found to have the original lattice structure of InN from X‐ray diffraction measurements. The 8‐20% of oxygen atoms has been evaluated to be incorporated in the InN layer by the energy dispersive X‐ray spectroscopy. The PL spectra have been affected by temperature. While a PL‐peak intensity increases with temperature decrease, a PL‐peak shifts toward the longer wavelength. Such red‐shift tendency is opposite to the case of other III‐V compounds. This anomalous temperature effect has been proved from variation of PL spectra with time after excitation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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A compact tunable laser module integrating a newly developed DBR/Ring laser and an extremely-high- Δ PLC wavelength locker is demonstrated with narrow spectral linewidth of <100 kHz across the full C-band.

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