ELECTRONIC-PROPERTIES AND MICROSTRUCTURE OF SI76GE23.95P0.05 ALLOYS PRODUCED BY MECHANICAL ALLOYING

High-energy ball-milled and hot-pressed silicon-germanium alloys are c haracterized for their microstructure and electronic properities in th eir different stages of production as a function of milling time. The analysis covers the characterization by X-ray diffractometry (XRD) (on both powders and compacts), the compositional examination by X-ray en ergy spectroscopy (EDS), macrostructural investigation by density and microhardness measurements, and finally the determination of the tempe rature-dependent conductivity. Milling is performed in agate vessels a nd a considerable wear of the milling media is found leading to a resi stivity of more than 40 MOMEGA for milling times longer than 150 h. Ot herwise the electronic properties do not depend upon processing time. Electronic properties of powder compacts can be either interpreted in terms of hopping conductivity for disordered systems in the high-tempe rature range of 100 to 300 K, or with fluctuations of the n-type dopin g level. The microstructural investigations reveal a concentration pro file inside the grains from which it is concluded that solid-state dif fusion plays a major role for a mechanically driven alloy formation.