Multivalley effect on electronic states in Si quantum dots

Electronic states in Si quantum dots are theoretically examined, considering a multivalley structure of conduction band. In quantum dots smaller than about 5 nm, one-electron energy levels in equivalent valleys are filled consecutively with increasing the number of electrons N. Owing to the absence of intervalley spin-couplings, high-spin states are realized more often in small magnetic fields, than in GaAs quantum dots. In much larger dots, electrons are accommodated in a valley, making the highest spin of S = N/2, to gain the exchange energy. (C) 2002 Elsevier Science B.V. All rights reserved.