Electrical and structural characterization of Mo/Si contact to n-GaAs

Mo/Si contacts to n-GaAs are fabricated by deposition of three alternate layers of Mo and Si using e-beam deposition process. The electrical and structural characteristics are studied as a function of annealing temperatures (320 to 800 degree C for five min) to study silicide formation and its effect on the electrical properties of Schottky diodes. The best ideality factor is 1.38 for a contact annealed at 470 degree C. The least value of saturation current density based on thermionic-field emission model is 1.23x10-7 A/cm2 for a contact annealed at 320 degree C. This results in a barrier height of 0.76 V. The electrical properties degrade when the contacts are annealed at 800 degree C for 5 min. The capacitance--voltage characteristics do not follow the depletion model because of incomplete silicide formation. This incomplete silicide formation is observed by Auger analysis which indicates that in layered contacts Mo does not diffuse into silicon but Si does diffuse into Mo to form a silicide