As higher operating voltages have become more common, the performance limitations of Schottky devices have become more obvious. Conventional Schottky designs use a planar structure similar to that shown in the figure. For planar structures to achieve breakdown voltages of 100 V and above with an acceptable reverse leakage current, they must use a carefully designed P-type guard-ring structure, a high-resistivity silicon epitaxial layer, and a high Schottky barrier height. The disadvantage to this structure is that the guard ring injects minority carriers into the semiconductor drift region which decreases the rectifiers’ switching speed. The high-resistivity silicon and high Schottky-barrier height also contribute to increased on-state voltage drop and to a lesser degree slower switching speeds. As the operating voltage moves to 100 V and above, planar Schottky rectifiers tend to lose their advantage of high switching speed and low forward-voltage drop to a substantial degree. These limitations can be overcome by using the trench MOS barrier Schottky (TMBS) rectifier technology from Vishay.