1.5‐µm emission of naturally‐oxidized InN crystals grown by MOVPE

Abstract

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)

Fabricating gratings on nitrides grown by MOVPE for DFB lasers

“…Issues associated with grating overgrowth need to be examined to establish a DFB laser structure. We did not assess optical properties, including the temperature dependence of photoluminescence, since crystal quality at this point is inadequate for effective lasers [10]. We also formed corrugation gratings in the GaN surface in the structure shown in Fig.…”

“…Improving the surface roughness of the MOVPE layer helps suppress these fluctuations, since roughness induces fluctuations in EB resist thickness and affects grating widths. The irregular features in the etched grooves may be attributable to inadequate crystal quality in the InN epitaxial layer [10]. Figure 3 is an AFM image of an InN surface with grating periods of 200 nm.…”