Quantum phase-change materials on amorphous silicon film doped with impurities

Abstract

The quantum phase change represents a transition to crystallizing quantum structure from amorphous silicon doped with impurities prepared in sputtering and depositing process by pulsed laser interaction, in which the silicon nanocrystals and the Yb-Er nanoalloy with direct bandgap are dramatic generated in irradiation process of laser or coherent electron beam, respectively. Here, the resonance among photon, electron and phonon occurs on surface with various impurities for quantum phase change, such as quantum dots crystallizing. It is demonstrated that the crystallizing process is faster and more stable while the plasmon energy produced by laser photon is near the phonon energy in annealing of laser irradiation, or while the energy of coherent electron is close to the phonon energy. Through quantum phase transition, the nanocrystals with various structures are observed in the TEM images, where the change characteristics in the low-dimensional quantum phase occur. It is interesting that the quantum phase change is obviously different in various impurities on surface of Si film, where the stronger condensing in crystallization doped with oxygen or erbium is measured. Under irradiation of coherent electron beam for suitable time, the nanostructure of Yb-Er alloy is observed on silicon, in which we find the new electron states near 0.93 eV for better emission at 1350 nm in the second communication window. And in the alloy of Yb-Er, the Er condensing and clustering are avoided in the crystallizing process for better emission near 1550 nm in the third optical communication window.