Volume 86, Issue 10, 15 November 1999
Index of content:
- DEVICE PHYSICS (PACS 85)
86(1999); http://dx.doi.org/10.1063/1.371591View Description Hide Description
We present experimental and device model results for electron only, hole only, and bipolar organic light-emitting diodes fabricated using a soluble poly (p-phenylene vinylene) based polymer. Current–voltage characteristics were measured for a series of electron only devices in which the polymer thickness was varied. The curves were described using a device model from which the electron mobility parameters were extracted. Similarly, the hole mobility parameters were extracted using a device model description of characteristics for a series of hole only devices where the barrier to hole injection was varied by appropriate choices of hole injecting electrode. The electron and hole mobilities extracted from the single carrier devices are then used, without additional adjustable parameters, to describe the measured current–voltage characteristics of a series of bipolar devices where both the device thickness and contacts were varied. The model successfully describes the characteristics of single carrier and bipolar devices as a function of polymer thickness and for structures that are contact limited, space charge limited, and for cases in between. We find qualitative agreement between the device model and measured external luminance for a thickness series of devices. We investigate the sensitivity of the device model calculations to the magnitude of the bimolecular recombination rate prefactor.
86(1999); http://dx.doi.org/10.1063/1.371592View Description Hide Description
We present a theoretical study on the dynamical properties of three-dimensional arrays of Josephson junctions. Our results indicate that such superconducting networks represent highly sensitive three-dimensional superconducting quantum interference devices (3D SQUIDs) having some major advantages in comparison with conventional planar SQUIDs. The voltage response function of 3D SQUIDs is directly related to the vector character of external electromagnetic fields. The theory developed here allows the three-dimensional reconstruction of a detected external field including phase information about the field variables. Applications include the design of magnetometers,gradiometers, and particle detectors.
86(1999); http://dx.doi.org/10.1063/1.371593View Description Hide Description
The process and reproducibility of transverse magnetic recording are studied by micromagnetic simulation using the Landau–Lifshitz–Gilbert equation and compared with longitudinal recording. The magnetization process of the recording medium by a conventional thin-film head is simulated for various anisotropic fields of media. It is confirmed that the transverse bit can be recorded by using a conventional head and medium at high-bit density. The magnetic-field component perpendicular to the medium is very important for magnetization reversal. In transverse recording, there is a disadvantage in that the field perpendicular to the medium along the bit direction is very small. The transverse recording bits can be detected by a magnetoresistive element with two sensing regions at each end that have opposing biases of different signs. As the track width becomes narrow, the output for transverse bits becomes large relative to that for longitudinal bits.
86(1999); http://dx.doi.org/10.1063/1.371594View Description Hide Description
We present measurements of the nonlinear surface impedance and the third-order intermodulation distortion (IMD) of a microstrip resonator, which is initially in the as-processed state and subsequently annealed at 450–600 °C. of the as-processed sample in the high-dissipated-power range is explained in terms of the vortices in weak links. In the low-dissipated-power range, outputs of IMD are changed by annealing the resonator, and the minimum IMD generation is obtained with a sample annealed at 500 °C. By comparing the IMD generation of the samples with the crystalline structure measured by x-ray diffraction and transmission electron microscopy, it is shown that IMD of the film is generated at lattice distortions of the a−b plane in grains and grain boundaries.