Elimination of Persistent Photoconductivity and Improvement in Si Activation Coefficient by Al Spatial Separation from Ga and Si in Al–Ga–As:Si Solid System –a Novel Short Period AlAs/n-GaAs Superlattice–

Abstract

A superlattice with an exceptionally short period composed of 15 Å AlAs and 25 Å selectively Si doped GaAs is grown by molecular beam epitaxy (MBE). The persistent photoconductivity (PPC) is drastically decreased by the Al and Ga separation, and deep level formation is effectively suppressed by the Al and Si separation compared with n-Al x Ga 1- x As ( x >0.25), which has the same bandgap as the superlattice. Consequently, an extremely high quality Al–Ga–As:Si solid system is realized for the first time with high donor activation coefficient and low activation energy (<10 meV) for thermal carrier generation.