Title: Exciton in closed and opened quantum dot
Author(s):

	M.V.Tkach (Fedkovych Chernivtsi National University, 2, Kotsyubinskoho Str.,Chernivtsi, 58012, Ukraine) ,
	Ju.O.Seti (Fedkovych Chernivtsi National University, 2, Kotsyubinskoho St.,Chernivtsi, 58012, Ukraine)

The theory of exciton spectrum in spherically symmetric states for the three- shell closed spherical quantum dot is proposed. The evolution of the exciton spectrum while varying the outer well thickness from zero (stationary spectrum of single closed spherical quantum dot) to infinity (quasistationary spectrum of a single open spherical quantum dot) is investigated. The mechanism of damping (semiwidth) of quasistationary states due to the redistribution over the energy levels of probability of exciton location in the space of two inner shells of nanosystem is studied. It is shown that the three shell closed spherical quantum dot of a rather big thickness of the outer well quite sufficiently and exactly reflects the basic properties of the quasistationary exciton spectrum in a single open spherical quantum dot.

Key words: spherical quantum dot, quasistationary state, exciton energy spectrum
PACS: 71.15.Dx, 73.21.La