Oxidized porous silicon field emission devices

Abstract

A low voltage vacuum field emission device and method for manufacturing is provided. The devices are fabricated by anodizing a heavily doped silicon wafer substrate (12) in concentrated HF solution, forming extremely sharp silicon tips (18) at the silicon to porous silicon interface. The resulting porous silicon layer is then oxidized, and a metal film (22) is deposited by evaporation on the porous silicon. Silicon substrate (12) is the cathode, and metal film dots (22) are the anodes. The I-V characteristics for the field emission devices follow Fowler-Nordheim curves over three decades of current. The I-V characteristics are also utterly independent of temperature up to 250° C. When the oxidized porous silicon layer (OPSL) is about 5000 Å, substantial current is obtained with less than 10 volts. Recent experiments leave no doubt that the charge transport is in the vacuum of the pores. A silicon wafer that contains an OPSL may prove to be a very useful material for the fabrication of low voltage, low noise field emitters for vacuum microelectronics.