Effect of interface roughness on performance of AlGaAs/InGaAs/GaAs resonant tunneling diodes

The interface roughness of a GaAs/AlGaAs/InGaAs double-barrier-quantum-well structure was controllably altered by changing substrate surface misorient ation and growth interruption time at metal organic vapor-phase epitaxy (MO VPE) growth interfaces. Atomic force microscopy (AFM) and X-ray reflectance measurements were used to quantify the interface roughness. The InGaAs qua ntum wells grown on singular substrates exhibit an island growth mode morph ology, while step-bunched growth is observed on the misoriented substrates. A short growth interruption time, of typically similar to 15 s, can decrea se the InGaAs/AlGaAs interface roughness. The low-temperature I-V character istics of the resonant tunneling diodes based on this quantum-well structur e are found to be sensitive to the quantum-well interface roughness. The me asured interfacial roughness was used as input to a numerical simulation of device performance. (C) 1998 Elsevier Science B.V. All rights reserved.