HALL FACTOR AND DRIFT MOBILITY FOR HOLE TRANSPORT IN STRAINED SI1-XGEX ALLOYS

Hole transport in B-doped strained Si1-xGex has been studied using Hal l measurements for baron concentrations from 2X10(18) to 7.5X10(18) cm (-3) with Ge content 0 less than or equal to x less than or equal to 0 .36. By keeping the B flux constant during the molecular beam epitaxy growth of sets of samples and only varying the Si and Ge fluxes, we we re able to prepare samples for an accurate determination of the Hall f actor based on using the established relationship between B-doping con centration and resistivity for pure Si. It was found that the Hall fac tor drops considerably when the Ge content is increased. Determined Ha ll factor values are compared with calculated values taking into accou nt the full valence band structure and various scattering mechanisms. The hole drift mobility has been derived from our measured Hall mobili ty using the determined Hall factor for the corresponding Ge content, We find that, depending on the doping concentration, the drift mobilit y can be higher for strained layers containing Ge. The grown layers we re also characterized using x-ray diffraction, where the Ge contents a nd layer thicknesses could be confirmed. Temperature dependent measure ments from 50 K to room temperature have also been made. (C) 1997 Amer ican Institute of Physics.