We have demonstrated a new type of transferred electron effect amplifier diode through computer simulation and experiment. The new GaAs diode is subcritically doped and has a cathode which limits the injection of carriers into the diode. In subcritically-doped amplifier diodes with ohmic contacts, excess carrier injection into the n-layer creates a power absorbing low field region near the cathode. Furthermore, the excess carrier injection causes the negative conductance to decrease rapidly with increasing rf drive and to disappear completely at a relatively low power level.