Interband tunnelling in semiconductor heterostructures

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Abstract
We describe an approach for the investigation of the interband tunnelling in semiconductor heterostructures made from materials based on the transfer Hamiltonian formalism and kp band model. Contrary to methods used earlier, this approach allows one to obtain not only the transmission coefficients but also resonant tunnelling times corresponding to the transitions through each barrier of a double-barrier structure taking into account the mixing of electron, light-hole (LH) and heavy-hole (HH) states. The equation for the tunnel matrix element is derived using the isotropic eight-band kp model for structures under bias. The analytical formulae for calculation of the tunnel matrix element, transmission coefficients and resonant tunnelling times are obtained for resonant tunnelling structures (RTSs) with type II heterojunctions under flatband conditions. The interband tunnelling in the InAs/AlSb/GaSb RTS is investigated using these formulae. It is shown that the resonant tunnelling times corresponding to transitions through the left and right barriers of a symmetrical RTS may differ by orders of magnitude owing to the spin-orbit interaction in the case of nonzero in-plane wavevector and depend significantly on the mixing of electron, LH and HH states.