Avalanche Characteristics of Silicide Schottky Barrier Diodes

摘要

The thesis investigates the use of an avalanche Platinum Silicide (PtSi) Schottky Barrier Diode as a detector in fiber optic communication systems for the 1.3 to 1.5 micron spectral region. The avalanche process is used to amplify the signal prior to electrical interfacing in order to enhance the signal-to-noise ratio. The proper environment for avalanche use is when the system is pre amplifier noise limited. The amount of multiplication is predicted by the impact ionization coefficients for electrons and holes, alpha and Beta, respectively. Detectors should be constructed of materials where alpha and Beta differ greatly, and then the multiplication should be initiated by the carrier with the higher ionization coefficient. By using PtSi Schottky diodes, where alpha > Beta, pure electron injection can be accomplished by irradiating with photons of energy psi < Hnu < Eg (where psi is the Schottky Barrier height and Eg is the bandgap of silicon), thus maximizing multiplication and minimizing noise. Experimental results on the PtSi diodes studied showed high dark currents at room temperature and premature reverse breakdown which prevented multiplication. However, values from previous reported results allow us to predict a multiplication of 68 with an excess-noise factor of 11.1, an NEP of 2.5 x 10 to the minus 8th power watts, and finally a gain-bandwidth product of 242 Ghz. (RH)