Arrays of 10 polysilicon field emitter tips were fabricated using plasma etch and oxidized to form sharp tips. Phosphorus doped polysilicon tips emit at around 10-15 V regardless of the degree of their sharpness. Similarly, intrinsic polysilicon tips emit at around 50 V ͑at 2 m tip to anode spacing͒. The same turn on voltages have been observed on flat polysilicon surfaces. Field emission data of the diode structures revealed a significant difference between phosphorous doped and intrinsic polysilicon tips and flat surfaces. The 3/2 /␤ versus applied voltage was obtained from the transconductance data and was used to compare the performance of the doped and intrinsic polysilicon tips. A qualitative comparison of 3/2 /␤ ratio reveals an increase in the effective work function of the intrinsic polysilicon device which is related to the field penetration inside the emitting surfaces. Furthermore, field emission data reveal the conduction limitation of the intrinsic polysilicon films associated with the single carrier injection mechanism.

Carbon films deposited at relatively low temperatures were studied as a coating for polysilicon substrates to provide enhancement of the electron field emission. Undoped and phosphor doped polysilicon substrates were coated by carbon films grown by a very high frequency chemical vapor deposition process. Critical process parameters include substrate temperature of 225°C, pressure of 56 mTorr, loaded power of 2 W/cm 2 , and discharge frequency of 56 MHz. The substrates were pretreated prior to film deposition, and bias enhanced nucleation was performed in hydrogen/C 6 H 14 plasma. A carbon layer was grown to a thickness of 700 nm. Field emission measurements were performed in an ultrahigh vacuum chamber equipped with an electron gun, a carousel for five samples, and a Faraday cup. A multigrid quasispheric energy analyzer was used for Auger electron spectroscopy and electron energy loss spectroscopy characterization. Additionally, before and after field emission measurements, the secondary emission coefficient was measured by a scanning electron beam, which provided a two-dimensional map of the sample surface. The field emission current was measured in a diode configuration using a spacer thickness of 45-55 m through a current collection window 2ϫ5 mm 2 . Emission current-voltage curves were measured from three different regions of every sample by shifting the current collection window over the sample. A surface conditioning effect was observed, resulting in stabilization and better reproducibility of the emission current-voltage characteristics. The most significant changes in emission characteristics were observed in undoped polysilicon substrates with carbon coatings. Low deposition temperatures make this coating process very attractive because of its compatibility with addressing circuitry based on either silicon or poly-, microcrystalline, or amorphous silicon.

Silicon dioxide films were reactively sputter deposited in argon/oxygen ambient using RF magnetron sputter deposition techniques. A substantial drop in the deposition rate at high enough partial pressure of the oxygen which is typical in reactive sputtering was observed. The best quality silicon dioxide films were obtained at the lower deposition rate, close to the deposition rate transition point. Higher quality films were obtained at higher RF powers with higher deposition rates. However, at 800 Watts RF, the so called negative ion effect dominates and results in higher surface roughness of the films, as seen by AFM results. Various characterization techniques including ellipsometry and wet chemical etching were used to compare stoichiometry and film density, respectively. MOS capacitor characterization along with breakdown voltages were also measured as a means of qualifying the films.