Using first-principles methods, systematic calculations were made of the defect formation energies and transition energy levels of group-III and group-V impurities doped in H passivated Si quantum dots as functions of the quantum dot size. The general chemical trends found in the quantum dots were similar to that found in bulk Si. It was shown that defect formation energy and transition energy level increased when the size of the quantum dot decreased; thus, doping in small Si quantum dots becomes more difficult. BSi has the lowest acceptor transition energy

level, and it was more stable near the surface than at the centre of the H passivated Si quantum dot. On the other hand, PSi has the smallest donor ionization energy, and it prefers to stay at the interior of the H passivated Si quantum dot. The general chemical trends and the dependence on the quantum dot size were explained in terms of the atomic chemical potentials and quantum confinement effects.

Chemical Trends of Defect Formation in Si Quantum Dots - the Case of Group-III and Group-V Dopants. Q.Xu, J.W.Luo, S.S.Li, J.B.Xia, J.Li, S.H.Wei: Physical Review B, 2007, 75[23], 235304