The effect of molecular-beam-epitaxial growth conditions on the electrical characteristics of In0.52Al0.48As/In0.53Ga0.47As resonant tunneling diodes

We have investigated the dependence of the performance characteristics of In0.52 Al0.48As/ In0.53 Ga0.47 As resonant tunneling diodes upon molecular-beam-epitaxial growth parameters. The roughness of the growth front, leading to intrawell-size fluctuations and the V/III flux ratio at a fixed growth temperature are found to be important parameters affecting the performance of these devices. By means of a simple model, we have semiquantitatively related the peak current to the interface roughness. Defects and traps in the In0.52 Al0.48 As barriers, on the other hand, produced partially by nonoptimal V/III flux ratios, may produce shunt paths for tunneling, again reducing the resonant tunneling current peak-to-valley ratio. Under optimum growth conditions we have measured current peak-to-valley ratios of 6.1 and 21.6 at 300 and 77 K, respectively. These are the best values reported so far for this heterostructure system.