Interface roughness scattering in AlAs/InGaAs resonant tunneling diodes with an InAs subwell

We present simulation results on the current-voltage (I-V) characteristics of an InP-based AlAs/InGaAs resonant tunneling diode (RTD) with InAs subwell. Space-charge limited transport is accounted for using a self-consistent electrostatic potential calculated using the Hartree approximation. Three-dimensional scattering is simulated using the recently developed multiple sequential scattering theory. Interface roughness scattering is found to be dominant over polar phonon scattering in the devices studied. Of particular interest is interface-roughness (IR) scattering at the InGaAs/AlAs and InGaAs/InAs interfaces and its impact on the valley current. The existence of a critical terrace size that maximizes IR scattering is identified through simulation. The origin of the asymmetry commonly measured in the RTD I-V characteristic is discussed with respect to asymmetries in interface scattering. The use of the InAs subwell and associated interface roughness scattering to tune the peak current while keeping a nearly constant current peak-to-valley ratio is demonstrated.