Enhanced Stark Tuning of Single InAs $(211)B$ Quantum Dots due to Nonlinear Piezoelectric Effect in Zincblende Nanostructures

Enhanced Stark Tuning of Single InAs $(211) B$ Quantum Dots due to Nonlinear Piezoelectric Effect in Zincblende Nanostructures

S. Germanis, C. Katsidis, S. Tsintzos, A. Stavrinidis, G. Konstantinidis, N. Florini, J. Kioseoglou, G. P. Dimitrakopulos, Th. Kehagias, Z. Hatzopoulos, and N. T. Pelekanos

Phys. Rev. Applied 6, 014004 – Published 13 July 2016

Abstract

We report enhanced Stark tuning of single exciton lines in self-assembled $(211) B$ InAs quantum dots (QDs) as a consequence of pronounced piezoelectric effects in polar orientations, making this QD system particularly sensitive to relatively “small” applied external fields. The Stark shifts in the first hundreds of kilovolts per centimeter of applied external field are at least 2.5 times larger, compared to those observed in nonpiezoelectric (100) InAs QDs of similar size. To account quantitatively for the observed transition energies and Stark shifts, we utilize a graded In-composition potential profile, as deduced from local strain analysis performed on high-resolution transmission microscopy images of the QDs. Our results provide a direct demonstration of the importance of nonlinear piezoelectric effects in zincblende semiconductors.

Received 4 November 2015

DOI:https://doi.org/10.1103/PhysRevApplied.6.014004

Physics Subject Headings (PhySH)

Piezoelectricity Stark effect

Nanostructures Quantum dots Zinc-blende structure

High-resolution transmission electron microscopy

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

S. Germanis^1,2, C. Katsidis¹, S. Tsintzos², A. Stavrinidis², G. Konstantinidis², N. Florini³, J. Kioseoglou³, G. P. Dimitrakopulos³, Th. Kehagias³, Z. Hatzopoulos^2,4, and N. T. Pelekanos^1,2,*

¹Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion, Greece
²Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion, Greece
³Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
⁴Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion, Greece

^*Corresponding author. pelekano@materials.uoc.gr

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 6, Iss. 1 — July 2016

Subject Areas

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
(a) Conduction-band profiles of a 3-nm $(211) B$ $InAs / GaAs$ QD illustrating the influence of the nonlinear PZ effect in reversing the direction of the internal field. (b) Schematic representation of the total diode structure. (c) Top view SEM image of a bonded device. (d) Macro-PL spectrum (blue line) from the active region of the diode, showing characteristic emission from the QDs and ${QW}_{1}$ at 100 K. The sharp-peaked spectrum in red is micro-PL emission through nanoapertures opened on the top metal layer.
Reuse & Permissions
Figure 2
(a) Variation of HH and LH transition energies of ${QW}_{1}$ as a function of external bias at 100 K. The dotted lines represent theoretical estimates of the ${QW}_{1}$ transitions. (b) Calibration curve (red line) between external bias and applied electric field extrapolated from the experimental points (dots) obtained by fitting the ${QW}_{1}$ transitions for each bias. (c),(d) PL images recorded for various values of the applied electric field at 100 K from two different single QDs.
Reuse & Permissions
Figure 3
(a) HRTEM image depicting an InAs QD embedded in $GaAs (211) B$ along the [ $01 \bar{1}$ ] projection direction. (b) Corresponding GPA strain map showing an average $ϵ_{x x} = 0$ in-plane strain (color bar). (c) GPA strain map along the growth direction illustrating the variation of the $ϵ_{z z}$ strain inside the QD with the GaAs lattice as reference. The shape of the QD is roughly delineated, while the tilted arrow denotes the WL. (d) Corresponding line profile of the $ϵ_{z z}$ strain along the dotted arrow in (c) showing the progressive increase of $ϵ_{z z}$ from the base towards the apex region of the QD.
Reuse & Permissions
Figure 4
(a) Experimental values (dots) of the QD $X$ -transition energy versus applied electric field and calculated curve (red line) including nonlinear PZ terms. For comparison, the calculated curve with only linear PZ terms taken into account is also shown (dashed line). (b) Comparison of Stark shifts between $(211) B$ and (100) QDs showing the potential of PZ QDs in obtaining enormous Stark shifts compared to non-PZ QDs. (c) Calculated Stark shifts of the $X$ -transition energy of QDs with heights of 2 and 3 nm, either for pure InAs (dashed lines) or for graded 74% to 30% In-content profile (solid lines). The inset depicts the conduction-band profiles and respective electron ground wave functions for the 2- and 3-nm-graded QDs at zero-applied electric field. The numbers in each case represent the probability of finding the electron inside the dot.
Reuse & Permissions

Physical Review Applied