A 60 GHz microwave resonance investigation of shallowly formed InAs quantum dots embedded in GaAs

Abstract

Shallowly formed InAs quantum dots (QDs) embedded in GaAs are investigated by Optically Detected Microwave Resonance (ODMR) technique. The low temperature (1.6 K) photoluminescence (PL) spectrum reveals a two-peak structure which is attributed to two different classes of QDs: smaller and larger in size. V-band (60 GHz) ODMR is selectively detected in each of the peaks and depending on the PL detection energy, a different ODMR spectrum is obtained. Detection in the high-energy band reveals a low-field negative signal which is ascribed to cyclotron resonance of the electron in the two-dimensional wetting layer, corresponding to an effective mass of 0.067 m0. The microwave-induced signal at higher fields (~1.1 T) is tentatively attributed to magnetic resonance transitions between spin states of the holes confined in the smaller QDs. When monitoring the emission of the larger QDs, the obtained microwave-induced signal is negative while the resonance line at low field, associated with the cyclotron resonance, is no longer present. The V-band ODMR spectra are compared with W-band (94 GHz) measurements obtained for the same QD structure.