Volume 93, Issue 7, 01 April 2003
Index of content:
Enhancement of ultraviolet upconversion in and codoped amorphous fluoride film prepared by pulsed laser deposition93(2003); http://dx.doi.org/10.1063/1.1557775View Description Hide Description
amorphous fluoride film was prepared by pulsed laser deposition. Ultraviolet and blue up-conversion emissions were observed under infrared excitation at 978 nm. In comparison with the upconversion of the target, the ultraviolet emissions are enhanced greatly. The enhancement is attributed to a decrease of the Judd–Ofelt parameter induced by pulsed laser deposition, which precludes the transition rate from to and enhances the energy transfer process and populates the level:
93(2003); http://dx.doi.org/10.1063/1.1541103View Description Hide Description
Si dangling bondinterface defects were probed by electron spin resonance in entities of (100)Si with ultrathin grown in ozonated de-ionized water solution at room temperature. After photodesorption of passivating hydrogen, appears with densities up to a value five times larger than the one standardly attained with high temperature thermal growth. Thus standard quality thermal interfaceproperties, as exposed by the -type defects criterion (interface traps), are not obtained by oxidation in ozonated water solutions at room temperature. The interface quality may be upgraded by providing additional thermal budget. Yet standard qualitity is still not attained after vacuum annealing at
93(2003); http://dx.doi.org/10.1063/1.1560564View Description Hide Description
Terahertz time–domain spectral techniques are applied to the characterization of a He discharge plasma. Electro-optically sampling of the electric field of a quasi-unipolar terahertz pulse transmitted through the plasma has allowed both the real and imaginary parts of the plasma permittivity to be simultaneously measured over a large spectral range. The plasma density and the collisional frequency are determined within a 30 ps duration measurement window. An anomalously high collisional frequency has been measured.
93(2003); http://dx.doi.org/10.1063/1.1558992View Description Hide Description
The effect of Mn substitution on ferroelectric and antiferromagnetic properties of the system has been studied. It is seen that, with the increase in Mn content, there is a contraction in unit cell volume. Since the cell volume contraction is isotropic, lattice distortion remains the same and so is the ferroelectric transition temperature Further, it is observed that the presence of Mn does not affect the loss tangent (tan δ) of the samples. On the contrary, with increase in Mn content, a small but linear enhancement in the magnetization is observed.
93(2003); http://dx.doi.org/10.1063/1.1560563View Description Hide Description
The band gap of pseudomorphically strained alloys has been measured using optical absorptionspectroscopy.X-ray diffractionmeasurements indicated that the in-plane lattice parameter of the film equaled that of the underlying GaN layer. For strained it was determined that the band gap shift versus composition is given by eV for Our results contradict some recent reports that has a relatively small bowing parameter. Possible reasons for the discrepancies are discussed.