Observation of cyclotron resonance in an InAs/GaAs wetting layer with shallowly formed quantum dots

A thin InAs/GaAs wetting layer with shallowly formed InAs quantum dots (QD’s) is investigated by means of optically detected microwave resonance spectroscopy. The absorption of W-band (95 GHz) microwaves is observed via the detection of changes in the total photoluminescence intensity of the InAs QD’s. A strong and anisotropic signal at low fields is ascribed to cyclotron resonance of the electron in the two-dimensional wetting layer, corresponding to an effective mass of ${0.053m}_0.$ Further microwave-induced signals at higher fields are tentatively attributed to magnetic resonance transitions between spin states of the holes confined in the shallow dots.