Power Diode Structures Realized on (113) oriented Boron Doped Diamond

Abstract

Molybdenum, ruthenium, and platinum contacts covered by the gold capping layer were used for preparation of pseudo-vertical Schottky barrier diodes on (113) oriented homoepitaxial boron-doped diamond. After metal deposition, diodes were stabilized by annealing for 20 minutes at 300 ˚C and their IV characteristics were measured at temperatures from 30 to 180 °C. Results show that all three metals can be used to realize Schottky diodes with sufficient forward and blocking capability. Moreover, molybdenum and ruthenium can also be used to create a stable ohmic contact on heavily doped contact p ++ layer. Molybdenum provides optimum properties: a sufficient Schottky barrier height providing low leakage at a level of 10-8 A/cm2 and an acceptable forward voltage drop of 3.80V@JF=1kA/cm2 (measured at 150 °C), the rectifying ratio then reaches 1011 over the entire temperature range under study. Ruthenium contacts exhibit lower Schottky barrier, their forward voltage drop is thus lower (2.85V@JF=1kA/cm2@150 °C), but leakage increases rapidly with temperature. Platinum provides the highest Schottky barrier and guarantees the lowest level of the leakage (<10-8 A/cm2). However, the diodes have poorer forward characteristics: their ideality factor and forward voltage is high (7.35V@JF=1kA/cm2@150 °C). Maximum realizable diode area and achievable breakdown field (0.8MV/cm) then depend on the number of crystal defects (namely threading dislocations) appearing in the diode low-doped drift region.