Minority Carrier Injection in High-Barrier Si-Schottky Diodes

In this paper, we investigate the presence of minority carriers and their role in charge carrier transport in silicon (Si) Schottky diodes with a high potential barrier. Using TCAD simulations along with an analytical model, we show that an inversion charge is induced at the metal-semiconductor (MS) interface in a high-barrier Schottky diode which imparts bipolar-type current characteristics to otherwise a unipolar Schottky diode, even at low-injection operation. In such a high-barrier diode, minority diffusion also becomes important along with the majority carrier thermionic emission and therefore cannot be neglected, unlike in a conventional Schottky diode. The presence of minority carriers at low injection in a high-barrier Si Schottky diode has been experimentally verified via a prior-reported two-diode electrical test method, reverse recovery measurements, and by measuring infrared electroluminescence. It is also shown, via TCAD simulations, that the diffusion component becomes more pronounced in case of a reduced Gummel number and at elevated temperatures.