Observation of field-induced electron emission in porous polycrystalline silicon nano-structured diode

Field-induced electron emission properties of porous poly-silicon nano-structured (PNS) diodes were investigated as a function of anodizing conditions, including morphological analysis, various kinds of top electrode thickness and the measuring substrate temperature. Also, the vacuum packaging process was performed by the normal glass frit method. The PNS layer was formed on heavily-doped n-type < 100 > Si substrate. Non-doped poly-silicon layer was grown by low-pressure chemical vapor deposition (LPCVD) to a thickness of 2mm. Subsequently, the poly-silicon layer was anodized in a mixed solution HF (50 wt%): ethanol (99.8 wt%) = 1:1 as a function of anodizing condition. After anodizing, the PNS layer was thermally oxidized for 1 hr at 900 °C. Subsequently, the top electrode was deposited as a function of Au thickness using E-beam evaporator and, in order to establish ohmic contact, thermally evaporated Al was deposited on the back side of a Si substrate. The prepared PNS diode was packaged using the normal vacuum sealing method. After the vacuum sealing process, the PNS diode was mounted on the PC measurement table. When a positive bias was applied to the top electrode, the electron emission was observed, which was caused by field-induced electron emission through the top metal.