Studies of porous silicon field emitters

Recent work on field emitters has shown that a thin layer of porous silicon formed on the surface of pyramidal p‐type silicon emitters can dramatically improve their emission characteristics, both in terms of the maximum emission current obtained and also the uniformity of emission between different pyramids [Wilshaw and Boswell, J. Vac. Sci. Technol. B 12, 662 (1994)]. A transmission electron microscope (TEM) study of the emitting surface of such pyramids is presented which shows that they are covered with a high density of surface asperities. TEM studies and electrical characterization are presented for two contrasting porous silicon morphologies.