The plasmon resonance in the cadmium selenide semiconductor nanocrystals with different doping types

The effect of the type of doping (surface (I) or bulk (II) doping) on the character of the dipole plasmon mode in semiconductor CdSe nanocrystals has been studied. It was found that in case I (donors located on the surface of the nanocrystal) the collective mode had a rotational character and only the angular degrees of freedom were excited. On the contrary, in case II the charge of the dopant impurities was distributed throughout the system and plasmon excitation was the oscillation of delocalized charge carriers in the direction normal to the surface. It was shown that the position of the resonance line was determined not only by the concentration of free charges, but also by the character of their collective motion determining by the type of doping.