Electron field emission characteristics of textured silicon surface

A textured silicon surface was prepared by chemical etching. The textured surface was covered with small silicon tips. The base diameter of the tips is random and the size is from less than 1–10 μm. A field emission emitter that shows a lower turn-on voltage has been fabricated by using aqueous potassium-hydroxide solutions with isopropyl alcohol added as a complexing agent. The silicon wafers were (100) monocrystalline n-type with a resistivity of 0.01 Ω cm. A texturing process using dilute inorganic alkaline in isopropyl alcohol solution is investigated. This causes the formation of randomly distributed pyramids on the (100) cyrstallographic plane without any masking pattern. Dilute alkaline solutions show a low-etching rate of typically 0.5 μm/min. The anisotropy arises from hydrogen bubbles which are able to stay on the silicon surface for a short time during etching. The diameter of the bubbles, their density, and the rate of the etching reaction define the geometry of the textured silicon surface. The silicon tip size and the density is affected by the concentration of isopropyl alcohol, potassium hydroxide, pretreatment of silicon substrate, and the temperature of the etchant. The turn-on voltage of the textured silicon surface was approximately at 25 V/μm when the emission current density reaches 1 μA/cm². This compared with the turn-on field about 35 V/μm on a silicon tip array fabricated by using an isotropic etching solution of nitric acid. A silicon carbide layer was formed on the textured silicon surface by using metal vapor vacuum arc ion implantation. The turn-on voltage can be lowered to approximately 9 V/μm when the emission current density reaches 1 μA/cm². © 2001 American Vacuum Society.