Strained heterostructures are now widely used to realize high-performance lasers. Highly mismatched epitaxy also produces defect-free quantum dots via an island growth mode. The characteristics of high-speed strained quantum well and quantum dot lasers are described. It is seen that substantial improvements in small-signal modulation bandwidth are obtained in both 1 lm (48 GHz) and 1.55 lm (26 ...

We propose a theoretical model to describe the strain-induced linear electro-optic (Pockels) effect in centro-symmetric crystals. The general formulation is presented and the specific case of the strained silicon is investigated in detail because of its attractive properties for integrated optics. The outcome of this analysis is a linear relation between the second order susceptibility tensor a...

We employ a methodology, based on established approaches for determining the critical thickness for strain relaxation in planar films, to determine critical dimensions for coherently strained coaxial nanowire heterostructures. The model is developed and executed for various specific core-shell heterostructures in 111 zinc blende and 0001 wurtzite geometries. These calculations reveal that criti...

Blood clots perform an essential mechanical task, yet the mechanical behavior of fibrin fibers, which form the structural framework of a clot, is largely unknown. By using combined atomic force-fluorescence microscopy, we determined the elastic limit and extensibility of individual fibers. Fibrin fibers can be strained 180% (2.8-fold extension) without sustaining permanent lengthening, and they...

Reconstructed point defects in graphene are created by electron irradiation and annealing. By applying electron microscopy and density functional theory, it is shown that the strain field around these defects reaches far into the unperturbed hexagonal network and that metal atoms have a high affinity to the nonperfect and strained regions of graphene. Metal atoms are attracted by reconstructed ...

Metalorganic chemical vapor deposition-grown In0.4Ga0.6As0.995N0.005 quantum well ~QW! lasers have been realized, at an emission wavelength of 1.295 mm, with threshold and transparency current densities as low as 211 A/cm ~for L52000 mm! and 75 A/cm, respectively. The utilization of a tensile-strained GaAs0.67P0.33 buffer layer and GaAs0.85P0.15 barrier layers allows a highly-compressively-stra...

A new GaAs/InGaAs/InGaP compound semiconductor nanotube material structure was designed and fabricated in this work. A thin, InGaAs-strained material layer was designed in the nanotube structure, which can directionally roll up a strained heterostructure through a normal wet etching process. The compound semiconductor nanotube structure was grown by gas-source molecular beam epitaxy. A good cry...

A study of the long-range, local and electronic structure of Nd0.5Sr0.5MnO3 films of varying thickness between 500 and 2000 Å has been performed. Local structure measurements at the Sr K-edge reveal a reduction of the Mn–O–Mn bond angles in films below 1000 Å. Spin-polarized measurements reveal splitting of the Mn 3d eg state in the strained region of the films and are consistent with a two-lay...

From observations of self-assembly of Ge quantum dots directed by substrate morphology, we propose the concept of control of ordering in heteroepitaxy by a local strain-mediated surface chemical potential. Using quite simple lithography, we demonstrate directed quantum dot ordering. The strain part of the chemical potential is caused by the spatially nonuniform relaxation of the strained layer,...

Using ab initio modeling we demonstrate that H atoms can break strained Si─O bonds in continuous amorphous silicon dioxide (a-SiO(2)) networks, resulting in a new defect consisting of a threefold-coordinated Si atom with an unpaired electron facing a hydroxyl group, adding to the density of dangling bond defects, such as E' centers. The energy barriers to form this defect from interstitial H at...