A field effect transistor having a highly doped gate wherein both the gate and the channel are different semiconductors with an energy band relationship that provides a barrier to both electrons and holes. The energy band relationship is staggered so that tunneling of electrons from the channel into the gate and holes from the gate into the channel is suppressed. An example structure is an InP light p conductivity type channel material (2) with a heavily doped AlInAs p⁺⁺ conductivity type gate (1).