Dependence of the GaAs/AlGaAs superlattice ionization rate on Al content

Abstract
Al content dependence of GaAs/Alx Ga1−xAs superlattice ionization rates was studied. The electron ionization rate is enhanced when the AlGaAs of the barrier is a direct transition type. It is drastically reduced at the Γ‐X band crossover in the AlGaAs layer. The ionization rate ratio (hole to electron) as determined by excess multiplication noise measurement is reduced from a value of 0.5 at x=0.3 to 0.14 at x=0.45. At higher values of x, corresponding to the onset of indirect electron transitions, the noise is increased.