Roughness on resonant tunneling characteristics

InGaAs/InAlAs heterostructures lattice-matched to InP have emerged as an important material system for electrical and optical devices. Since it has been deduced theoretically that the characteristics of such devices are affected by the interface roughness of the heterostructures, the degree of roughness should be evaluated and controlled. Atomic force microscopy (AFM) is suitable for evaluating interface roughness because its horizontal resolution is close to the size of the roughness which is sensitive to the device characteristics. In this study we clarify the effects of growth conditions and of the surface misorientation angle of InP substrates on the interface roughness by using AFM to observe the surfaces of In/sub 0.53/Ga/sub 0.47/As, In/sub 0.52/Al/sub 0.48/As, and InP. We also show the effects of interface roughness on the InGaAs/InAlAs resonant tunneling characteristics and demonstrate that growing a pseudosmooth interface is an effective way to improve the characteristics.