In this paper, we investigated Schottky and metal-semiconductor-metal (MSM) photodetector structures fabricated on
GaN templates with <i>in situ</i> SiN<sub>x</sub> nanonetwork, which were shown to reduce the dislocation densities significantly in the
overgrown material. The GaN layers were grown by metalorganic chemical vapor deposition. The peak responsivity of
the Schottky photodetectors on templates with SiN<sub>x</sub> nanonetwork was measured to be 0.16 A/W, significantly larger
than that for the control samples (0.09 A/W). The MSM photodetectors on templates with SiNx nanonetwork also
showed significantly enhanced photoresponsivity (100 A/W) when compared to the control sample without any SiNx
(30 A/W) and photoconductive gain. The improvement in the photoresponsivity in both Schottky and MSM
photodetector structures with the use of SiN<sub>x</sub> nanonetwork is due to the reduction of dislocation densities.