Ai. Onipko et al., ON ADDITIONAL CONDUCTANCE QUANTIZATION AND RELATED EFFECTS OF AN ELECTRIC-FIELD IN 2D QUANTUM POINT CONTACTS, Physica. B, Condensed matter, 225(1-2), 1996, pp. 125-131
Influence of the electric field on the quantum point contact (QPC) dif
ferential conductance is studied in two cases of well-developed transm
ission spectrum of(a) step-like and(b) resonance character. These are
exemplified by a symmetric rectangular constriction and double-bend co
nstriction in two-dimensional electron gas. It is shown that an additi
onal structure in the constriction-conductance dependence on the Fermi
energy (referred sometimes as half integer quantization) reflects the
specific field distribution in the contact region at moderate fields
and is washed out by nonlinear field effects produced by the potential
variation inside the contact. To study held effects, we suggest an an
alytical expression for the transmission probability, which includes a
s particular cases two models used previously to confirm and to reject
the possibility of the QPC conductance quantization by value e(2)/h.
We also briefly discuss the case of resonance doubling accompanied by
two-times decrease of the resonance intensity, representing another ex
ample of transformations in the QPC conductance, which have the same o
rigin.