Size and shape dependence of the lowest conduction band states in GaAs quantum dots

Using a recently developed new scheme, we investigated the electronic struc ture of the lowest conduction band states of cuboid GaAs quantum dots with different shapes and sizes in a wide range from 4 to 120a (a is the lattice constant). The critical edge length of the direct/indirect crossover in Ga As cuboid quantum dots depends on the size and shape of the quantum dots. A s a deduction we also discussed the critical size of direct/indirect transi tion in GaAs quantum wires and thin films.