Influence of thiol coupling on photoluminescence of near surface InAs quantum dots

Photoluminescence (PL) of near surface InAs quantum dots (QDs) has been stu died as a function of the distance to the surface (30, 20, 10, 6 nm). We ob serve a strong decrease in the QD PL intensity with decreasing barrier thic kness. Nevertheless the QDs still show reasonably strong PL intensity even when they are only 10 nm beneath the surface. After tile deposition of self -assemble;I monolayers of octadecylthiol, we observe an increase ill PL int ensity up to a factor of 1.87. Such an enhancement is attributed to a decre ase in the density of surface states. This demonstrates that near surface I nAs QDs ale very sensitive to changes of the surface conditions and the dep osition of octadecylthiol monolayer may be used to increase, their sensitiv ity which is promising toward future bio-sensor applications.