Defect-induced performance enhancement in moderately dislocated (108cm?2) GaAs tunnel diodes

In this work we investigate experimentally and theoretically the performance of metamorphic/dislocated GaAs based tunnel diodes with dislocation densities (Nd) ranging from 2×105 to 2×10⁹ cm^-2. As it is commonly reported, we observe no performance degradation for Nd<;10⁶ cm^-2 and very severe performance degradation for devices with Nd>10⁹ cm^-2). However, interestingly we observe a noticeable improvement of peak current densities for diodes with moderate dislocation densities (~20% at N=2.4×10⁸ cm^-2). Simulation of the tunnel diode characteristics, assuming a defect state assisted-tunneling/hoping, allows to partially account for this observation.