I have seen many authors introduce the Dresselhaus contribution after averaging over the growth direction of a confining quantum well or wetting layer, thus giving the linear expression and a cubic (the latter often being neglected). However, in a dot, there is also quantum confinement in the x-y directions. Whilst this may not be so tightly confined as in the z direction, it is of the same order as a typical quantum well width or less, so shouldn't one also average the Dresselhaus Hamiltonian over these lateral dimensions?

If this were carried out, though, the Dresselhaus term would disappear altogether (since = = 0). This does seem to be implied by some authors, who only consider the Rashba term. So far, though, I have not seen any explicit comments to the effect that the Dresselhaus term disappears. I was wondering if there is an issue here and if so, is there a general consensus?

Martin Vaughan