Normally-OFF Diamond Reverse Blocking MESFET

Schottky contacts have been used to fabricate normally-(OFF) lateral reverse-blocking MESFETs on p-type (boron-doped) O-terminated monocrystalline diamond. The devices utilized an ohmic source contact but both gate and drain contacts were Schottky in nature. Boron-doped p-channel diamond MESFETs reported to date display the less attractive normally-(ON) characteristics. Here, the normally-(OFF) transistor delivered a current level of similar to 1.5 mu Amm(-1) at a negative V-GS of 0.8 V and a transconductance (g(m)) of 16 mu Smm(-1), measured at room temperature (RT); at a temperature of 425 K, these values rose to similar to 70 mu Amm(-1) for /Ds and a g(m) value of 260 mu Smm(-1). In both cases, a negligible gate leakage current was measured with no breakdown apparent at the maximum field investigated here (3.7 x 10(5) V/m(-1)). The Schottky gate demonstrates a well-behaved control of the channel even at higher temperatures. The high-temperature operation, normally-(OFF) behavior, and diamond's inherent radiation hardness make this transistor promising for harsh environment applications.