(Page under construction - links will be added when available)

Home

Current Research:

Other Information:

Si/SiGe heterostructures are of interest for high speed and optoelectronic applications. Heterostructures are sensitive to the position and abruptness of the heterointerface. There is fundamental importance to understand, predict, and control interdiffusion of Si and Ge during processing. Much of the work that has contributed to our understanding of front end processes in silicon has yet to be matched for the SiGe and SiGeC alloys. I currently have several projects in this area:

Modeling Si-Ge Interdiffusion: (Mohammad Hasanuzzaman) Drawing on previously conducted research, we will develop self-consistent models describing the Si-Ge interdiffusion over a wide temperature range under different annealing ambients and accounting for interactions with dopant species and surface effects. At low temperature (below ~1000ºC) Si-Ge interdiffusion occurs via a vacancy exchange mechanism. To date, there have not been numerical simulations taking into account the different self-diffusivities of Si & Ge and accounting for the conservation of lattice sites. We are able to simulate diffusion under both inert and oxidizing ambients for low temperatures using published values of Si & Ge diffusivities. At higher temperatures, there is evidence that interstitials may play a role in the diffusion, similar to the case of Si self-diffusion.

Diffusion in SiGeC: (Samer Rizk) There is significant interest in the effect of C in retarding transient enhanced diffusion (TED) in SiGe structures. A number of studies have modeled the diffusion of B in SiGeC. However, most studies focus on a subset of the published experimental data. We combine different features of these models to provide a complete analysis of B diffusion in SiGeC. Additionally, we are working to extend this model to P and As diffusion.

Oxidation Kinetics: (Mohamed Rabie, Ahmed Fakhr) This project focuses on modeling oxidation kinetics of SiGe in one- and two-dimensions in wet, dry, and fluorinated dry ambients. We have proposed a model based on published data that is capable of predicting all the parameters of the oxidation process. The model parameters vary as a function of both temperature and Ge fraction. While this is expected, and the qualitative trends all match the underlying theory, we need to understand this dependence quantitatively so that the model provides predictive ability. The current model is 1D, and we are continuing to work to expand it to 2D.

Point Defect Characterization: (Kareem Shoukri, Mohamed Rabie) This project focuses on the direct characterization of point defects in bulk and thin-film SiGe. In particular we have shown that low temperature MBE growth of a Si or SiGe buffer layer may affect the concentration of grown-in vacancies in relaxed SiGe layers grown on top of the low temperature buffer layer.

Point Defect Injection: (Han Su) This project examines both qunatitatively and qualitatively the impact of surface reactions on point defects in SiGe. Understanding point injection phenomena in SiGe, in addition to being important in its own right, provides us with additional tools to investigate dopant diffusion mechanisms in SiGe.

This page was last updated on March 02, 2005