R. D Schaller and V. I. Klimov, “High Efficiency Carrier Multiplication in PbSe Nanocrystals: Implications for Solar Energy Conversion,” Physical Review Letters, Vol. 92, No. 18, 2004, pp. 186601-1-186601-4. doi:10.1103/PhysRevLett.92.186601
ABSTRACT: Quantum confinement effect in semiconductor quantum dots (QD's) of CdSe, ZnS and GaAs has been studied using the Brus Equation. It is found that the simple models obtained for the three different semiconductor nanocrystals exhibit the size dependence predicted by the particle-in-a-box model. The result shows that ground state confinement energy is inversely proportional to the size (radius). Thus, as one increases the radius (size), the confinement energy decreases, but never reaches zero. i.e., the lowest possible energy for the quantum dot sample is not zero.