Tunnel diodes $n^{++}$-GaAs:($\delta$-Si)/$p^{++}$-Al$_{0.4}$Ga$_{0.6}$As:(C) for connecting elements of multijunction laser photoconverters

Based on mathematical modeling, there has been proposed a new type of thermally stable connecting tunnel diode with an intermediate $i$-layer, which is promising for implementing highly efficient multijunction laser photoconverters. Two types of the $n^{++}$-GaAs/$p^{++}$-Al$_{0.4}$Ga$_{0.6}$As tunnel diode structures have been grown by molecular beam epitaxy: with and withput the intermediate $i$-GaAs layer. It has been experimentally demonstrated that the inclusion of a nanoscale $i$-layer between the $n^{++}$- and $p^{++}$-regions of the tunnel diode provides an increase in the density of peak tunneling current $J_p$. Due to the epitaxial wafer annealing which simulates a long-term process of epitaxial growth of multijunction laser-radiation photoconverters, the structure with the $i$-layer exhibited a 30% increase in peak tunneling current $J_p$.