Peak-to-valley ratio of 130:1 at 1 K in AlGaAs/GaAs/AlGaAs tunneling structures: evidence for suppressed dopant segregation

We report growth of AlGaAs/GaAs/AlGaAs double barrier resonant tunneling structures by gas source molecular beam epitaxy. Our tunneling diodes show a peak-to-valley ratio, P:V, of 113:1 at 4 K. At 1 K, the P:V ratio is 130:1. Not only are these tunneling characteristics the highest to date, they provide for the first time, a P:V ratio that continues to increase for temperatures below 4 K. We attribute our very high quality resonant tunneling characteristics to the reduction of dopant segregation (from the heavily doped contacts) into the intrinsic region. We show how dopant segregation can be reduced by chosing growth conditions that minimize As vacancies on the surface.