Annealing effects on the operation stability of ballistic electron emission from electrochemically oxidized nanocrystalline silicon diodes

Abstract

To improve the operation life of ballistic electron emission from nanocrystalline silicon diodes, thermal annealing effects have been studied for polycrystalline silicon (poly-Si) based devices. The experimental devices are constructed by sequentially depositing tungsten, anodized nanocrystalline poly-Si (NPS), and gold films upon glass substrates. The NPS films are partially oxidized by electrochemical oxidation treatment, and then annealed at 550 °C in vacuum or in a forming gas ambient. The electron emission efficiency and stability are investigated in relation to the compositional characterization of the respective NPS layers by thermal desorption spectroscopy. It is shown that removal of incorporated H2O molecules and hydrogen-related species from interfacial SiO2 films between silicon nanocrystallites is very effective to suppress interfacial scattering losses of electrons and to enhance the ballistic emission stability for long-term operation.