Resistance-voltage curves of n-on-p Hg1−хCdxTe long-wavelength infrared photodiodes forming 128-element array are measured in the temperature range of 40–150 K. Experimentally obtained characteristics are fitted by the simultaneous-mode nonlinear fitting program. The dark current mechanisms induced by diffusion, generation recombination, trap-assisted tunneling, band-to-band tunneling, and series resistance effect are included in the physical model for R-V curve fitting. Six characteristic parameters as function of temperature are extracted from measured R-V curves. The characteristics of extracted current components at low temperatures indicate significant contributions from tunneling effects, which is the dominant leakage current mechanism for reverse bias greater than approximately 50 mV. The Hg-vacancy-induced acceptor trap tends to invert to donor type at higher temperature, typically larger than 120 K, while it can maintain stable at the temperature of 60–40 K. The stable temperature of ion-implantation-induced traps is about 90–60 K, which possibly tends to be ionized at high temperature. However, a low operation temperature can induce the frozen effects of the ion-implantation-induced donor traps. Fitting certainty analysis shows that the error of one parameter can be magnified when one of the other types of dark current mechanisms dominates the dark current and is even infinitely enlarged under large reverse bias. The different bias regions at which each fitting parameter has the largest influence to the R-V curve should be ascertained. The results of the present work demonstrate that modeling of the dynamic resistance in small voltage range or at just operation temperature are insufficient for determining the mechanism of carrier transport across the Hg1−хCdxTe junction and a detailed theoretical study of the current-voltage characteristics in wider voltage range or at various temperatures should be carried out.
The Fever, Thrombocytopenia and Leukopenia Syndrome (FTLS) is caused by a bunyavirus known as the FTLS virus (FTLSV), which was recently discovered in China. We examined the epidemiological and etiological features of 637 laboratory-confirmed cases of FTLS with onset from January 2011 to December 2012 in Henan Province, China. The highest incidence of FTLS occurred between May and August: 76.5% of all laboratory-confirmed cases occurred during those four months. Of the laboratory-confirmed cases, 60.9% were in the 46–69 years old age groups; 96.1% (612/637) occurred in farmers; 98.1% (625/637) were reported from Xinyang Prefecture. During the same time period, 2047 cases were reported in China. The nucleotide and amino acid sequences of FTLSV strains identified during 2011–2012 in Henan Province were ≥96% identical. This findings provides insight for developing public-health interventions for the control and prevention of FTLS in epidemic area.
A data-processing approach has been developed to obtain device parameters from resistance-voltage ͑R-V͒ curves measured on long-wavelength HgCdTe n-on-p photodiodes. The physical model used for R-V curve fitting includes the dark current mechanisms induced by diffusion, generation recombination, trap-assisted tunneling, and band-to-band tunneling. Moreover, the series resistance effect is also taken into account. Six parameters, which include the dopant density N d in the n region, the ratio of mobility to lifetime of electrons n / n in the p region, the effective lifetime 0 in the depletion region, the relative energy position of trap level E t / E g and its density N t in the depletion region, and the series resistance R s , can be extracted from measured R-V curves. The fitting procedure has been presented in detail and the error ranges of the extracted parameters have been discussed. By fitting to the R-V characteristics of three long-wavelength devices with different Cd compositions, the applicability of our data-processing approach has been verified for obtaining those basic parameters.
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