South African Journal of Science
On-line version ISSN 1996-7489
Print version ISSN 0038-2353
BOTHA, A.E.. Numerical solution of multiband k·p model for tunnelling in type-II heterostructures. S. Afr. j. sci. [online]. 2009, vol.105, n.7-8, pp.294-298. ISSN 1996-7489.
A new and very general method was developed for calculating the charge and spin-resolved electron tunnelling in type-II heterojunctions. Starting from a multiband k·p description of the bulk energy-band structure, a multiband k·p Riccati equation was derived. The reflection and transmission coefficients were obtained for each channel by integrating the Riccati equation over the entire heterostructure. Numerical instability was reduced through this method, in which the multichannel log-derivative of the envelope function matrix, rather than the envelope function itself, was propagated. As an example, a six-band k·p Hamiltonian was used to calculate the current-voltage characteristics of a 10-nm wide InAs/GaSb/InAs single quantum well device which exhibited negative differential resistance at room temperature. The calculated current as a function of applied (bias) voltage was found to be in semi-quantitative agreement with the experiment, a result which indicated that inelastic transport mechanisms do not contribute significantly to the valley currents measured in this particular device.
Keywords : spin-dependent electron transport; semiconductor nanostructures.