Substrate-dependent porous Pt coating morphology under oblique-angle sputtering

Porous Pt coatings were deposited by oblique-angle sputtering (60–80°) on SiO 2 /GaN and SiO 2 /Si substrates to examine the influence of deposition angle and substrate type on coating morphology. Cross-sectional SEM revealed porous structures whose continuity depended on the underlying substrate. Films formed on SiO 2 /GaN exhibited relatively continuous porous morphologies over a wide angular range, whereas films on SiO 2 /Si showed morphological instability, including clustering, cracking, or delamination at higher deposition angles. XRD measurements indicated Pt (111) reflections, with variations in peak intensity depending on substrate and deposition angle. The observed substrate-dependent differences are discussed in relation to possible substrate-related or growth-related factors. These results provide a comparative assessment of substrate-dependent morphological stability in porous Pt coatings formed under oblique sputtering conditions.