Corbett in Orbit

Since the 1950s, there have been discussions concerning the need to develop a space power theory.1 In their attempts to formulate such a theory, strategists have noted the similarities of space operations to those of air and naval opera- tions. Consequently, many have attempted to derive a clearly articulated, all- encompassing space theory through analogy and comparison to either airpower or sea-control models. These efforts, however, as observers like the contempo- rary historian and strategist Colin Gray have noted, have not produced a theory addressing space operations and associated national interests

Time-gated electroluminescence spectroscopy of polymer light-emitting diodes as a probe of carrier dynamics and trapping

Journal ArticleWe present time-gated electroluminescence (EL) spectroscopy of a polyfluorene-based conjugated polymer. The technique is shown to be sensitive enough to pick out impurity emission orders of magnitude weaker than the cw emission. By considering the temperature dependence of the delayed emission spectra and also the dependence on a constant-bias offset it is shown that both geminate pair formation and carrier trapping during operation result in a long EL decay tail. The technique also provides a direct probe of the validity of the Einstein law in conjugated polymers. The diffusion mobility is found to exceed the drift mobility by a factor of 12

A Common-Path Heterodyne Interferometer for Surface Profiling in Microelectronic Fabrication

We describe the design of a common-path heterodyne laser interferometer for the surface profiling of micron-sized photopatterned features during the microelectronic fabrication process. The common-path design of the interferometer’s reference and measurement arms effectively removes any path length difference in the measurement which can be attributed to the movement of the target surface. It is shown that repeated surface profiling during the ion milling process allows the difference in etch rates between the photoresist layer and the exposed portions of the underlying substrate layer to be monitored online. A prototype apparatus has been assembled and results demonstrating the usefulness of the device are reported. The surface profiles of both a photopatterned nickel–iron trench and an unmasked aluminum trench are measured and compared to those obtained using a stylus-based scanning profiler and an atomic force microscope