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The systematic enhancement of ferromagnetic hysteresis loops for GaN implanted with high doses of Fe (5→10 at. %) takes place with an increase in the annealing temperature from 700 to 850 °C. The trends of magnetic properties coincide with the results of the increased full width at half maximum of triple axis diffraction for GaN (0002), including the appearance of GaFeN, the enhanced Fe-related photoluminescence transitions, and the systematic increase in sizes of symmetric spin ferromagnetic domains GaFeN in atomic force microscopy and magnetic force microscopy. [ABSTRACT FROM AUTHOR]

Transition related to the Mn–Zn interaction was observed in photoluminescence (PL) study of the InMnP:Zn epilayer and the peak position blueshifted with increasing Mn concentration. X-ray photoelectron spectroscopy was used to clarify the blueshift of the PL peak. The binding energy shifts of Mn 2p and Zn 2p core levels indicative of the interaction between Mn and Zn were observed. This mutual interaction between Mn 2p and Zn 2p agrees with the result that the Mn-related transition in InMnP:Zn codoped with Zn is shifted to the higher energy region in comparison with InMnP without additional doping of Zn. [ABSTRACT FROM AUTHOR]

We report a high power fundamental transverse mode operation of an optically pumped 1060 nm vertical-external-cavity surface-emitting laser. A diamond heat spreader was capillary bonded to the semiconductor surface. A 10 W continuous wave operation with optical-to-optical conversion efficiency of 44% was achieved at room temperature. The thermal rollover was not found up to a heat sink temperature of 60 °C. High efficiency and good thermal stability were mainly due to the optimization of epitaxial quality and the high conductivity of the diamond heat spreader. We have found that the increase of the round trip loss caused by the heat spreader was about 1%. [ABSTRACT FROM AUTHOR]

We report results of nanoscopic investigation of grain crystallographic orientations and ferroelectric domains by electron backscatter diffraction (EBSD) technique and piezoresponse force microscope (PFM), respectively, in (Bi1-xLax)4Ti3O12 (BLT) films for ferroelectric semiconductor memories. It is demonstrated that the EBSD technique is useful in characterizing nanoscale grain crystallographic orientations of BLT films. Comparison studies of grain orientations by EBSD technique and switching properties of ferroelectric domains by PFM show that c-axis parallel to normal oriented grains with almost linear dielectric properties have platelike morphology. However, a- or b-axis oriented grains with superior ferroelectric properties have ellipsoidal morphology with a size of less than 0.2 μm in long axis. Consequently, the suppression of the platelike structures through process controls is important for the realization of high-density BLT-based memories. [ABSTRACT FROM AUTHOR]

We report optical studies of high-quality 1.3 μm strain-compensated GaInNAs/GaAs single-quantum-well structures grown by metalorganic vapor phase epitaxy. Photoluminescence excitation (PLE) spectroscopy shows clearly the electronic structure of the two-dimensional quantum well. The transition energies between quantized states of the electrons and holes are in agreement with theoretical calculations based on the band anti-crossing model in which the localized N states interact with the extended states in the conduction band. We also investigated the polarization properties of the luminescence by polarized edge-emission measurements. Luminescence bands with different polarization characters arising from the electron to heavy-hole and light-hole transitions, respectively, have been identified and verify the transition assignment observed in the PLE spectrum. [ABSTRACT FROM AUTHOR]

We investigated the retention characteristics of (Bi,La)4Ti3O12 (BLT) capacitors and their lateral size effects in a fully integrated device structure. Unlike the commonly used Pb(Zr,Ti)O3 capacitors for ferroelectric random access memories (FeRAMs), which have poor opposite-state retention characteristics, BLT capacitors showed very stable characteristics in both the same- and the opposite-state retention tests. These good retention properties were closely related to the small amount of imprint in the BLT capacitors. In addition, the retention characteristics of BLT capacitors showed no practical degradation due to the size reduction, down to 0.49×0.64 μm2, which could be used for highly integrated FeRAMs of 32 MB density. [ABSTRACT FROM AUTHOR]

P-type bulk InP was prepared by the liquid encapsulated Czochralski method and subsequently diffused with Mn by heat treatment after the evaporation of Mn on top of InP:Zn using a molecular beam epitaxy system. The characteristics of Mn-diffused InMnP:Zn were investigated by an energy dispersive x-ray spectroscopy, photoluminescence, and a superconducting quantum interference device magnetometer measurements. The samples were characterized by transmission electron microscopy and no evidence of secondary phase formation of InMnP:Zn was found. The results of energy dispersive x-ray peak displayed injected concentration of Mn near 3%. The results of photoluminescence measurement showed that optical broad transitions related to Mn appeared around 1.2 eV and it was confirmed that the transitions around 1.2 eV were Mn-related band by the diffusion of Mn into InP:Zn. Clear ferromagnetic hysteresis loops were observed at 10 and 300 K and the temperature-dependent magnetization showed ferromagnetic behavior around 300 K, which is caused by carrier-mediated ferromagnetism in InMnP:Zn. It is found that a ferromagnetic semiconductor at room temperature can be formed in diluted magnetic semiconductor based on GaMnN and InMnP additionally co-doped with Mg and Zn, respectively. [ABSTRACT FROM AUTHOR]

Edge-terminated Schottky rectifiers fabricated on quasibulk GaN substrates showed a strong dependence of reverse breakdown voltage V[sub B] on contact dimension and on rectifier geometry (lateral versus vertical). For small diameter (75 μm) Schottky contacts, V[sub B] measured in the vertical geometry was ∼700 V, with an on-state resistance (R[sub ON]) of 3 mΩ cm2, producing a figure-of-merit V[sub B][sup 2]/R[sub ON] of 162.8 MW cm-2. Measured in the lateral geometry, these same rectifiers had V[sub B] of ∼250 V, R[sub ON] of 1.7 mΩ cm2 and figure-of-merit 36.5 MW cm-2. The forward turn-on voltage (V[sub F]) was ∼1.8 V (defined at a current density of 100 A cm-2), producing V[sub B]/V[sub F] ratios of 139–389. In very large diameter (∼5 mm) rectifiers, V[sub B] dropped to ∼6 V, but forward currents up to 500 mA were obtained in dc measurements. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]