Design of novel nanocrystalline composite materials by means of plasma CVD

Abstract

We discuss two examples of the application of nonisothermal plasma CVD for the design of novel nanocrystalline/amorphous composite materials. It is shown that the electronic and mechanical properties of the materials undergo dramatic change when the crystallite size decreases below 10 nm where the localization phenomena of charge carriers and phonons commence: The probability of the phonon assisted radiative recombination of the carriers increases resulting in an efficient photoluminescence from nanocrystalline silicon. The mechanical strength of nc-MeNx./a-SixN4 composites increases far above the values of the single components. In both cases, a small crystallite size of ≤ 2 nm, sharp interfaces free of dangling and weak bonds and an appropriate thickness of the amorphous matrix are needed. So far, only plasma CVD appears to be able to meet these stringent requirements.