Comparison of different bonding techniques for efficient strain transfer using piezoelectric actuators

Abstract

In this paper, strain transfer efficiencies from a single crystalline piezoelectric lead magnesium niobate-lead titanate substrate to a GaAs semiconductor membrane bonded on top are investigated using state-of-the-art x-ray diffraction (XRD) techniques and finite-element-method (FEM) simulations. Two different bonding techniques are studied, namely, gold-thermo-compression and polymer-based SU8 bonding. Our results show a much higher strain-transfer for the “soft” SU8 bonding in comparison to the “hard” bonding via gold-thermo-compression. A comparison between the XRD results and FEM simulations allows us to explain this unexpected result with the presence of complex interface structures between the different layers.

Inversion of the exciton built-in dipole moment in In(Ga)As quantum dots via nonlinear piezoelectric effect

“…3, 6, 38, and 40. We would also like to mention that we approximated the (experimental) absolute value of p/e at F p = 0 in the performed calculations by theoretically considering a shear pre-stress of s pre xy = 200 MPa. This pre-stress, which is already present in our device at F p = 0, is a common feature and is attributed to the bonding and poling process 33,34 . However, it has no qualitative influence on the presented behavior of p/e vs S 1 + S 2 , which, obviously, purely depends on the applied stress (which is estimated from the experimental data).…”

“…This is found to be highly anisotropic (with a ratio |S 1 |/|S 2 | ≈ 3.16), applied at 55 • with respect to [100] direction and with magnitudes (S 1 + S 2 ) as high as −180 MPa (see Supplemental Material 24 ). While this stress anisotropy is not expected for the [001] piezo cut used in this work, it is a common feature reported in the literature 19,33,34 .…”

Optomechanical tuning of the polarization properties of micropillar cavity systems with embedded quantum dots

“…However, the change of the mode splitting suggests that the strain delivered by the piezo is not completely isotropic in the plane since the extremely small anisotropy = (e xx − e yy ) causes a change of each axis of around 1 nm and cannot explain the voltage-induced splitting observed in the experiment. The existence of this anisotropy is indeed consistent with previous findings [36] and it is most likely related to imperfections arising in the wafer-bonding process [37]. We note that in this scenario, a highly anisotropic strain with e xx = −0.% and e yy = 0.24% is necessary to yield a tuning range as observed in the experiment.…”

Strain-Tunable GaAs Quantum Dot: A Nearly Dephasing-Free Source of Entangled Photon Pairs on Demand

“…The GaAs QDs -fabricated via Al droplet etching via molecular beam epitaxy at JKU Linz -are embedded in a planar distributed Bragg reflector cavity for increasing the photoluminescence intensity. The sample substrate is thinned down to a 30 µm thick micromembrane, which is bonded on top of a micro-machined [Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.72 -[PbTiO 3 ] 0.28 piezoelectric actuator [25,41,42] (for details on the sample and device fabrication see supplementary Sec. I A).…”