ENHANCEMENT OF SI HOLE MOBILITY IN COUPLED DELTA-DOPED WELLS

When two or more highly doped, thin (delta-doped) layers are placed in close proximity to one another it is found that an enhancement of the hole mobility occurs over that of a single delta (delta) layer as wel l as that of the Si bulk case. Hall mobilities of up to 2400 cm2 V-1 s -1 at 77 K have been obtained with delta layers spaced 200 angstrom ap art compared to a mobility of 280 cm2 V-1 s-1 for the single delta lay er. The conductivity of the coupled delta-doped well exceeds that of c omparable uniformly doped bulk layers, especially at lower temperature s. These types of structures show great promise in obtaining high mobi lities with high carrier densities for semiconductors grown by simple homoepitaxy.