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This report describes the successful realization of high‐quality semi‐polar (112¯2) ‐GaN templates grown on 100 mm diameter r‐plane patterned sapphire. Trench patterning is accomplished by plasma etching using a slanted SiNx mask that is formed by a resist‐reflow process and subsequent dry etching. Epitaxial overgrowth by MOVPE is optimized with the aid of in situ monitoring to trace GaN coalescence behavior and surface morphology. Wafer curvature at growth temperature exceeds typical values of c‐oriented GaN, whereas room‐temperature bow is spherical and comparable to polar material. Morphological and structural properties compare well with published data on 2 in. substrates. Threading dislocation densities of about 2 × 108 cm−2 and basal stacking fault densities in the order of 1 × 103 cm−1 are deduced from cathodoluminescence studies. Low residual impurity concentrations ([O, Si] < 1 × 1017 cm−3) have been verified.

We report further progress in the design and fabrication of high-order Bragg gratings defined by I-line projection lithography that are implemented in a high-power diode laser. Simulations of surface Bragg gratings with large duty cycles predict large reflectivities even for the 25th Bragg order. We implemented such Bragg gratings in high-power diode lasers and compared the spectral and electro-optical properties with diode lasers having seventh-order Bragg gratings. Details of the fabrication and encapsulation of the Bragg gratings will also be presented.

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