Effect of carbon coating on electron field emission from polysilicon

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/cm2, and discharge frequency of 56 MHz. The substrates were pretreated prior to film deposition, and bias enhanced nucleation was performed in hydrogen/C6H14 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 ...