Structural and optoelectronic properties of amorphous GaN thin films

A Three Demultiplexer C-Band Using Angled Multimode Interference in GaN–SiO2 Slot Waveguide Structures

“…Propagation losses in the GaN layers are influenced directly from the practical fabrication of the layers and should be considered prior to manufacturing of the suggested device. Some of the contributors to the propagation losses are surface roughness due to surface roughness and free carrier loss [32] alongside the crystallization level of GaN [33]. The scattering loss is expected to be higher than that stated in [32] (~2.5 dB/cm) because of the large device dimensions, despite the large wavelength.…”

“…GaN (stack) waveguide losses from the fabrication process consisting of scattering loss, free carriers loss, and crystallization level impact are discussed later in this paper and are described in detail by Chen, H [32], and Al-Zouhbi [33].…”

“…To lower these losses, surface roughness can be improved by better controlling the dry etching speeds at grain boundaries or by small power applications. Amorphous GaN in comparison with crystalline GaN has the advantages of lower manufacturing costs, better suitability for deposition on various substrates, while relieving the difficulty of lattice matching of the Ga-N bond; in contrast, however, it may additionally have significant material absorption of up to 13 dB/cm [33]. Recently, researchers show the ability to fabricate GaN rib waveguides on Ga 2 O 3 substrate, using a wet-etch process for improving side-wall verticality and reduction of waveguide surface roughness.…”