University of Cambridge > Talks.cam > Semiconductor Physics Group Seminars > Electrostatic manipulation of self-assembled InAs/GaAs quantum dots (QDs) and interface fluctuation GaAs/AlAs QDs (IF-QDs) by focused laser assisted diffusion of Manganese interstitial ions in GaAs/AlAs/GaMnAs resonant tunnelling diode (RTD) structures

Electrostatic manipulation of self-assembled InAs/GaAs quantum dots (QDs) and interface fluctuation GaAs/AlAs QDs (IF-QDs) by focused laser assisted diffusion of Manganese interstitial ions in GaAs/AlAs/GaMnAs resonant tunnelling diode (RTD) structures

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The effect of locally introducing small clusters of interstitial Manganese ions near both IF-QDs and InAs/GaAs QDs embedded within GaAs/AlAs/GaMnAs pin-RTDs has been studied. Experiments and simulations show that the microscopic random fluctuations in the electric field generated by these ions can be as strong as 200 kV/cm (in the growth direction) and 40 kV/cm (in the growth plane) in the plane of the QD. The resulting shifts in the quantum confined Stark effect of the weakly confined IF-QDs have been used to optically probe such nanoscale potential fluctuations [1]. The local introduction of these charges by focused laser assisted diffusion near InAs/GaAs-QDs have demonstrated site-specific, electrically driven, bright few QD-nano-LEDs. We have also been able to locally manipulate carrier relaxation processes from excited wetting layer states into the InAs/GaAs QD by the nanoscale electrostatic preferential current channelling phenomena (or nanoLED) previously reported in such pin-RTD structures [2,3].

[1] A. Nasir et.al., Phys. Rev. B. 85, 195317 (2012) [2] F. Intonti et.al., Appl. Phys. Lett. 98, 183102 (2011) [3] O. Makarovsky et.al., Advanced Materials 22, 3176 (2010

This talk is part of the Semiconductor Physics Group Seminars series.

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