Growth and transport properties of epitaxial lattice matched half Heusler CoTiSb/InAlAs/InP(001) heterostructures

We demonstrate the integration of the lattice matched single crystal epitaxial Half Heusler compound CoTiSb with In0.52Al0.48As/InP(001) heterostructures using molecular beam epitaxy. CoTiSb belongs to the subset of Half Heusler compounds that is expected to be semiconducting, despite being composed entirely of metallic constituents. The lattice matching and epitaxial alignment of the CoTiSb films were confirmed by reflection high energy electron diffraction and X-ray diffraction. Temperature dependent transport measurements indicate semiconducting-like behavior, with a room temperature Hall mobility of 530 cm2/Vs and background Hall carrier density of 9.0 × 1017 cm−3, which is comparable to n-Si with similar carrier density. Below 100 K, the films show a large negative magnetoresistance, and possible origins of this negative magnetoresistance are discussed.