Analysis of Thermally Grown Oxides on Microperforated Copper Sheets

Abstract

Copper oxides have some interesting photocatalytic properties and reasonably low price which makes them applicable as PN transistors. However, to obtain the best performance it is necessary to increase the specific working surface of materials which plays a key role in many applications. Furthermore, by ordered spacing and heterojunction formation it is possible to fabricate the systems with specific dedicated properties, like for example PN photovoltaic junction. The conducted research analyses the mechanical properties, stress distributions, and thermal stability of metal–oxide structures with such advanced geometries. Micro-perforation of thin Cu sheet was selected for the study, as it can both enhance the free surface of the substrate and decrease the number of sites of thermal stress occurrence. Both Cu-Cu2O and Cu-CuO layers were simulated using finite element analysis. The model based on fixed geometry of square shaped samples of dimensions of 156 × 156 mm was applied to thin metal plates holes-patterned covered on top by 1-3 μm thick oxide layers. On the other hand, the influence of plate thickness was found to be important in terms of structure durability. A good agreement between the simulation and the experimental data was achieved. The critical delamination temperature of c.a. 473-483 K was estimated for both oxide layers. The verification of the simulation/computation model was done by analyzing perforated and non-perforated Cu Electrolytic Tough Pitch (ETP) sheets. Two methods, FIB-TEM and surface scan using a profilometer, were selected. The first verified the decohesion of the oxide coatings from the metal support after exceeding the temperature of 523 K The issue that was also noticed is the susceptibility for peeling in the inner surface of the holes.