Vertical structure Schottky barrier diode fabrication using insulating diamond substrate

To obtain high current operation of the diamond SBDs, the device should be designed in a vertical type structure in order to minimize the device on-resistance. In this research, we have designed and developed the technology for fabrication of diamond vertical structure Schottky barrier diodes (vSBD) by utilizing Inductively Coupled Plasma etching technique. Free standing CVD grown epilayers (p(+)/P- = 100 mu m/5 mu m) were obtained by removing the base lb substrate on which the epi-layers were grown, using ICP etching process. After ICP etching, ohmic contact (Ti/Pt/Au) was made at the bottom of p+ layer, and Schottky contact (Mo) was made at top side on oxidized surface of p(-) layer, to realize Diamond/Mo vSBDs and were analyzed for their electrical characteristics. The SBDs showed a reproducible ideality factor close to 1.0, and a barrier height of 1.4 eV, with a small standard deviation of 0.06 and 0.12 eV respectively. Diodes in the vertical structure exhibited R. with a battery uniformity irrespective of their location on the wafer, compared the diodes in a pseudo-vertical structure. Room temperature I-V analysis of the fabricated vSBDs (70 mu m size) exhibited a high forward current density of 2980 A/cm(2) (= 0.115 A) with a low RonS of 8 m Omega cm(2), which could be attained due to the vertical geometry of the diodes. At the high temperature operation, still higher current density could be obtained. Satisfactory reverse blocking characteristics also could be achieved with a breakdown field of 2.7 MV/cm for small size diodes. (C) 2010 Elsevier B.V. All rights reserved.