TUNNELING REAL-SPACE TRANSFER INDUCED BY WAVE-FUNCTION HYBRIDIZATION IN MODULATION-DOPED HETEROSTRUCTURES

We report a new tunneling mechanism in modulation-doped heterostructures based on wave function hybridization. We show that hybrid wave functions can be formed across the heterojunction by growing highly doped n-p layers below the undoped GaAs layer. The hybridization creates the condition for hot electrons to transfer by tunneling from the high-mobility GaAs channel through the heterojunction to the low-mobility AlGaAs layer and results in a negative differential resistance. The hybrid nature of the wave functions and the smaller energies needed to achieve the transfer across the heterojunction suggest that this effect will occur at lower applied fields than for thermionic emission or tunneling between localized states in adjacent quantum wells.