HYDROGEN PASSIVATION OF SILICON SURFACES - A CLASSICAL MOLECULAR-DYNAMICS STUDY

We present a computationally efficient classical many-body potential t hat is capable of predicting the energetics of bulk silicon, silicon s urfaces, and the interaction of hydrogen with silicon. The potential i ncludes well established models for one-component Si and H systems and incorporates a newly developed Si-H interaction. It is shown that the present model yields hydrogen diffusion barriers, hydrogen abstractio n, and H-2 desorption reactions on silicon surfaces in excellent agree ment with experiment and/or previous ab initio results. Derailed molec ular-dynamics simulations an performed that elucidate the complex bala nce between adsorption and abstraction reactions during hydrogen passi vation on Si(100) surfaces. We find a very high sticking coefficient o f 0.6 for atomic hydrogen on clean Si(100)2X1 surfaces and provide a d etailed qualitative and quantitative explanation for this prediction. Furthermore, we find that there are two efficient competing surface re actions of atomic hydrogen with monohydride Si surfaces. One is the El ey-Rideal abstraction of H-2 molecules, and the other one is adsorptio n. Additionally, adsorbed hydrogen on hydrogenated Si surfaces acts as a reservoir that can lead to complete passivation of Si surfaces desp ite the efficient creation of voids in the hydrogen layer by the abstr action.