HgZnTe-based detectors for LWIR NASA applications

The initial goal was to grow and characterize HgZnTe and determine if it indeed had the advantageous properties that were predicted. Researchers grew both bulk and liquid phase epitaxial HgZnTe. It was determined that HgZnTe had the following properties: (1) microhardness at least 50 percent greater than HgCdTe of equivalent bandgap; (2) Hg annealing rates of at least 2 to 4 times longer than HgCdTe; and (3) higher Hg vacancy formation energies. This early work did not focus on one specific composition (x-value) of HgZnTe since NASA was interested in HgZnTe's potential for a variety of applications. Since the beginning of 1989, researchers have been concentrating, however, on the liquid phase growth of very long wavelength infrared (VLWIR) HgZnTe (cutoff approx. equals 17 microns at 65K) to address the requirements of the Earth Observing System (EOS). Since there are no device models to predict the advantages in reliability one can gain with increased microhardness, surface stability, etc., one must fabricate HgZnTe detectors and assess their relative bake stability (accelerated life test behavior) compared with HgCdTe devices fabricated in the same manner. Researchers chose to fabricate HIT detectors as a development vehicle for this program because high performance in the VLWIR has been demonstrated with HgCdTe HIT detectors and the HgCdTe HIT process should be applicable to HgZnTe. HIT detectors have a significant advantage for satellite applications since these devices dissipate much less power than conventional photoconductors to achieve the same responsivity

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Taking silk: an empirical study of the award of Queen’s Counsel status 1981-2015

This article considers which junior barristers are appointed to the rank of Queen’s Counsel. The criticisms of the old appointments system are discussed and statistical methods are used to assess whether the changes to the QC appointments system introduced in 2004 improved the prospects of appointment for groups, such as women, that were disadvantaged by the previous system. The results show that under the reformed system groups that were historically less likely to be appointed QCs, such as women, continue to be so. However it is discussed how this may (partly) be attributable to lower rates of application, rather than unfair discrimination among applicants

Stereomammography: Evaluation of depth perception using a virtual 3D cursor

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134910/1/mp9008.pd