Effect of Size and Dimensionality on the Band Gap and Conductivity of InAs, PbS, Ge, and Bi2S3 Nanostructured Semiconductors

The band gap and conductivity of a nano-semiconductor are tunable with the specimen size and dimensionality, and related mechanisms are under debating. From the perspective of bond orderlength- strength correlation, we have developed analytical expressions for investigating size- and dimensionality- induced change of the band gap, charge carrier concentration and conductivity of InAs, PbS, Ge, and Bi2S3 nano-semiconductor. Consistency in theoretical predictions, experimental observations, and numerical calculations clarified that size and dimensionality dependent these properties arise from surface strain and the associated quantum trap of binding energy. The surface-to-volume ratio is a key factor, which dominates size and dimensionality dependency.