Passivation of InAs surface quantum dots (SQDs) grown by molecular beam epitaxy is achieved by ex situ deposition of trimethylaluminum (TMA). Photoluminescence (PL) was enhanced ca. 2-fold after 5 TMA pulses by atomic layer deposition. Atomic force microscopy reveals that, unlike wet chemistry passivation with which InAs SQD shrinks and PL significantly blueshifts, TMA passivation preserves the InAs SQDs, leading to the suppression of blueshift compared to the wet chemistry passivation. X-ray photoelectron spectroscopy results suggests the removal of the InAs native oxides and their transformation into an AlOx layer through self-clean-up by TMA via ligand exchange reaction.