| For low to moderate current densities, current flow in Schottky barrier diodes (SBDs) is primarily due to majority carrier injection over the metal-semiconductor interface. However, at high current densities, such as are encountered in advanced integrated circuits, minority carrier effects become significant. The objective of this study was to experimentally verify and quantify minority carrier injection in platinum-silicide SBDs, develop boundary conditions expressing carrier injection at the metal-semiconductor interface which extend to high injection conditions, and correlate the results with numerical simulation. Two experimental measures of minority carrier injection have been investigated, minority carrier storage and conductivity modulation. Also, new methods have been devised to accurately determine the barrier height of the SBD from its I-V characteristics.;One dimensional numerical simulation results using traditional boundary conditions agree well with both charge storage and conductivity modulation measurements up to 5 x 10('4) A/cm('2). At higher current densities, however, there is significant difference between simple simulation results and experiment, and additional phenomena including hole tunneling, image-force induced band-gap shrinkage, hole barrier height lowering at high injection, Auger recombination, and lateral voltage drop are considered.;Minority carrier storage has been experimentally determined by integration of the reverse bias switching current which, after correction for capacitance stored charge, yields the minority carrier charge removed from the diode on switching from forward to reverse bias. The stored charge was found to increase monotonically both with temperature and forward biased current over the experimental range of 27(DEGREES)C to 125(DEGREES)C and 10('4) A/cm('2) to 10('5) A/cm('2). For 12.5 x 12 (mu)m unguarded SBDs fabricated on a 1 (mu)m thick n-type epitaxial layer, stored minority carrier charge at 10('5) A/cm('2) was on the order of 10('-5) C/cm('2). For guarded SBDs, the stored minority carrier charge was higher, on the order of 5 x 10('-5) C/cm('2) at 10('5) A/cm('2). Conductivity modulation was investigated by current-voltage measurements at current densities up to 4 x 10('5) A/cm('2) and was found to be appreciable, causing the series resistance of the diode to decrease by approximately a factor of 5 at the higher currents. |
