Elastic scattering centers in resonant tunneling diodes

Abstract
The effect of impurities placed in the wells of double-barrier resonant tunneling diodes on the current-voltage characteristics was experimentally determined. Four different double-barrier structures were grown by molecular beam epitaxy with n-type, p-type, undoped, and highly compensated doping in the center of the well. Resonant tunneling devices of various sizes were fabricated, and measured at 77 K. Systematic shifts in the peak position and peak to valley ratios were observed for the different dopant profiles. The shifts in peak position are correctly predicted by a ballistic model which includes the effects of band bending due to ionized impurities in the well. The doped devices showed a systematic decrease in the peak to valley ratio which is not predicted by the ballistic model. By scaling our results, it is apparent that in most cases unintentional background impurities are not sufficient to significantly degrade the current-voltage characteristics of resonant tunneling diodes.