NeoSilicon materials and silicon nanodevices

We propose a novel material NeoSilicon, in which both particle size and interparticle distance of nanocrystalline silicon (nc-Si) quantum dots are precisely controlled. New functions in electron transport, photon emission and electron emission are expected due to quantum effects at room temperature and large interaction between dots. The bandgap is determined by the particle size. The conductivity is controlled mainly by tunneling processes. The transport characteristics are also controlled by charge quantization effect. We present fabrication and characterization of NeoSilicon. Based on the idea of separation of the nucleation and the growth processes in plasma decomposition of silane, we have successfully prepared nc-Si particles of 8 nm in diameter with size dispersion of 1 nm, whose surfaces are covered by naturally formed oxide of 1.5 nm thickness. Further reduction of dot size is achieved to 4 nm using self-limiting oxidation processes. Single electron transport characteristics of nc-Si are demonstrated in both planar and vertical transistor structures. Highly efficient electron emission is observed in NeoSilicon samples. Photoluminescence intensity enhancement due to no-phonon-assisted indirect transition is observed in strongly confined nc-Si dots covered by oxide.