We report large (>10%) magnetization modulation by ferroelectric polarization reversal in the ferroelectric-ferromagnetic BaTiO3/La0.67Sr0.33MnO3 (BTO/LSMO) heterostructures. We find that the electrically induced change in magnetization is limited to the BTO/LSMO interface but extends about 3 nm deep into the LSMO layer—far beyond the expected screening length of metallic LSMO. It is suggested that this effect is due to a metal-insulator transition occurring at the BTO/LSMO interface as a result of electrostatic doping.

We report a unique growth and migration behavior of Ge nanocrystallites mediated by the presence of Si interstitials under thermal annealing at 900°C within an H2O ambient. The Ge nanocrystallites were previously generated by the selective oxidation of SiGe nanopillars and appeared to be very sensitive to the presence of Si interstitials that come either from adjacent Si3N4 layers or from within the oxidized nanopillars. A cooperative mechanism is proposed, wherein the Si interstitials aid in both the migration and coarsening of these Ge nanocrystallites through Ostwald ripening, while the Ge nanocrystallites, in turn, appear to enhance the generation of Si interstitials through catalytic decomposition of the Si-bearing layers.

An otherwise random, self-assembly of Ge quantum dots (QDs) on Si has been controlled by nano-patterning and oxidation to produce QDs with desired sizes, locations, and depths of penetration into the Si substrate. A heterostructure consisting of a thin amorphous interfacial oxide between the Ge QD and the Si substrate is shown to improve crystalline quality by de-coupling the lattice-matching constraint. A low dark current density of 1.1 lA/cm 2 and a high photocurrent enhancement up to 35 000 and 1500, respectively, for 1.5 mW incident illumination at 850 nm and 1160 nm was measured on our Ge QD-based metal-oxide-semiconductor photodiodes. V C 2012 American Institute of Physics. [http://dx.

A new phenomenon of highly localized, nanoscale oxidation of silicon-containing layers has been observed. The localized oxidation enhancement observed in both Si and Si(3)N(4) layers appears to be catalyzed by the migration of Ge quantum dots (QDs). The sizes, morphology, and distribution of the Ge QDs are influenced by the oxidation of the Si-bearing layers. A two-step mechanism of dissolution of Si within the Ge QDs prior to oxidation is proposed.

One key obstacle in fabricating efficient flexible and printable optoelectronic devices is the absence of ideal flexible transparent conductors with superior optical, electrical, and mechanical properties. Here, highperformance flexible transparent conductors are demonstrated using ultrathin (<10 nm) doped silver films, which exhibit an averaged visible transmittance of 80% without any antireflection coating, sheet resistance less than 20 Ω sq −1 , and mechanical stability over 1000 bending cycles. The conductor is prepared by doping silver with an additive metal (e.g., nickel, copper, titanium, chromium), and its various properties can be readily tuned by either using different doping metal species or controlling the dopant concentration. Centimeter-size, flexible polymer light-emitting diodes are fabricated using a nickel-doped silver-based electrode, and the devices exhibit 30% enhanced current efficiencies compared to their indium tin oxide counterparts, invariant emission spectra at large viewing angles, and operational stability for over 1200 bending circles. In addition, 6 in. flexible low-emissivity coatings are demonstrated using a copper-doped silver-based conductor, which transmit 85.2% of the visible light while rejecting over 90% of the infrared radiation beyond 1250 nm.