Electronic noise spectroscopy of indium gallium arsenide quantum dots

In this work In0.35Ga0.65As QDs have been probed for electronic defects and noise. Five samples with 0, 6, 9, 11 and 13 MLs of InGaAs in a GaAs matrix have been grown and fabricated. From RHEED, AFM, PL and Hall measurements, the 6 ML sample a quantum well structure while 9, 11 and 13 ML samples formed QDs in the GaAs matrix. The AFM and PL showed an increase in QD height with increasing number of monolayers and both showed single size distribution. The PL integral intensity also showed a decrease with increase in MLs, which indicated an increase in defects that caused non-radiative decays. From the Hall measurements, the mobility curves showed the 6 ML sample behaved like a remotely doped quantum well (QW). The carrier concentration temperature dependent curves showed bumps that indicated defects present in the samples. Deep level noise spectroscopy (DLNS) was used to probe the electronic defects and noise in the samples. The comparison of Hooge parameters between the samples did not show an increase in flicker noise for those with QDs. Four GR traps were recognized in the samples with three being detected in all five samples. The fourth defect was only present in the QD samples. The 13 ML sample had a defect with an activation energy of 0.1 eV and capture cross section on the order of 10-18 cm2, which indicated a defect associated only with the QDs and not with GaAs. Devices utilizing quantum dots in this type of system would not decrease the SNR and degrade device functionality.