Tunneling in In0.53Ga0.47As-InP double-barrier structures

We report the first observation of tunneling through In0.53Ga0.47As-InP double-barrier structures at 77 and 4.2 K. The tunneling peaks occur at voltages close to the predicted values of the subband levels of the quantum well. The observed values are symmetrical about zero bias, unlike the results for similar structures in the AlGaAs-GaAs system. The measured peak-to-valley ratios are low, being near to unity. This result is attributed to the presence of a large leakage current caused by conduction at the edges of the devices. We also report the observation of minima in the conductance curves due to the resonance levels in the continuum of states above the quantum well.