THE STRUCTURE OF SILICON-BASED AND GERMANIUM-BASED ALLOYS BY X-RAY ABSORPTION-SPECTROSCOPY

The use of the extended X-ray absorption fine structure for investigating the structure of amorphous silicon and germanium alloys is summarized. It is shown that the technique is very powerful for determining bond lengths, distribution of bond lengths and local coordination. The data on a-Si1-xGex:H, a-Si1-xCx:H, a-Ge1-xNx:H and a-Si1-xNx:H systems are presented and discussed. A common feature of all the alloys is the constancy of the average bond length as a function of composition. It was also found that in a-Si1-xGex:H there is a random distribution of atoms while in the other alloys there is a strong tendency toward chemical order.