A significantly high non‐Ohmic forward voltage has been observed inn‐GaAs/p‐Ge andp‐GaAs/n‐Ge injection heterojunction diodes which have hard reverse electrical characteristics and whose wide‐gap emitters were of relatively low doping levels. Theory and experiment are compared and conditions for enhancing this phenomenon are stated. An SEM micrograph of the grown Ge epitaxial layer is included and growth conditions are described.