BAND-EDGE PROPERTIES OF A SEMICONDUCTOR ALLOY - AN NMR-STUDY OF HG1-XCDXTE

We report Hg-199 NMR measurements of narrow-gap Hg1-xCdxTe alloys in t he range x=0.20-0.28. By studying temperature dependences, we have ide ntified intrinsic Knight shifts in these alloys. This provides a measu re of Hg orbital contributions to conduction-electron states, and we f ind a consistently strong average contribution from Hg s orbitals. Fur thermore, we identify local variations in the Knight shift with spatia l variations in conduction-electron densities and symmetries. These ch aracteristics have been related to randomly populated sites within the alloys. We also discuss Hg-199 chemical shifts and their relation to local orbital charges.