Influence of Thickness and Wavelength on the Mechanical Properties of a Compositionally Modulated Ceramic Thin Film

摘要

The hardness and modulus of thin (<1 mu m) ceramic films have been investigated using the differential mechanical properties microprobe (DMPM). The DMPM consists of a computer controlled ultra-low load indentation system with a special system that allows the elastic stiffness of the contact to be determined continuously during the indentation process. The films were deposited in a molecular beam epitaxy (MBE) system utilizing unique high temperature effusion cells. Two specimens have been studied. The fist is a wedge shaped layer of amorphous Al2 O3 on a silicon substrate. The thickness of the layer varies from 0 to 990 nm at the two extreme sides of a 3 in. silicon wafer. The effect of layer thickness on the hardness and modulus as measured with the DMPM has been quantified for this system. The second specimen is made up of 38 repetitions of alternating layers of crystalline TiO2 and amorphous Al2 O3. The wavelength of the composition modulation and the thickness of the film varies uniformly from 0 to 38 nm and from 0 to 1460 nm respectively across the 3 in. diameter of the silicon substrate. 17 refs., 5 figs. (ERA citation 14:015247)