On the voltage stability of lateral barriers in in-plane-gated structures

Lateral barriers in a two-dimensional electron gas were fabricated by laser-induced doping of GaAs/AlGaAs quantum well structures. The barrier heights of these insulating lines were analyzed as a function of voltage by temperature-dependent current measurements. The barrier height saturates for large bias voltages. This is connected with surprisingly high breakdown voltages of the sub-μm lateral barriers. We propose a model for in-plane-gated structures which can explain these effects by taking into account surface leakage currents and surface charges. The lateral band diagram and the barrier height as a function of voltage were calculated self-consistently using this model. The model and the calculations are in good agreement with experimentally determined barrier heights, depletion lengths, and time-dependent leakage currents.