Directed self-assembly of InAs quantum dots using in situ interference lithography

Laser interference lithography is used to directly pattern the growing surface during molecular beam epitaxy growth of self-assembled InAs quantum dots on GaAs (100) substrates. Arrays of few-monolayer high nano-islands are formed prior to InAs quantum dot growth, which we believe result from the surface diffusion promoted by transient photothermal gradients. The deposition of InAs on such a surface leads to the nucleation of quantum dots solely at the island sites. The number of dots per site is determined by the island size which varies with the laser energy intensity. We are able to achieve highly ordered dense arrays of quantum dots with a single nanosecond laser pulse exposure. InAs quantum dots formed in this fashion show bright narrow photoluminescence with a peak at 1.04 eV at 88 K.