Исследование пространственного распределения люминесценции в диапазоне 0.44-0.75 мкм CVD-ZnSe, легированного алюминием и железом

Spatial distribution of luminescence characteristics of CVD-ZnSe doped with Aluminum and both Aluminum and Iron by thermal diffusion were studied. The diffusion method leads to formation of two areas in crystal volume: (1) area with high aluminum concentration in which the luminescence of defective-impurity centers (DICs) dominates and exciton luminescence is absent and (2) area with low aluminum concentration in which exciton luminescence dominates. The border of two areas recognized on luminescence map is sharp that not corresponded to diffusion nature. The result is explained by assuming the anomalous nature of aluminum diffusion, leading to a sharp change in the aluminum concentration at a certain distance from the doping surface. Method of aluminum doping process applied in present paper leaded to weakens of well-known luminescence suppression effect by iron ions in ZnSe.

Feeding and body condition of an invasive fish species under different environmental conditions

ABSTRACT Diet, energy density (ED) and relative condition factor (Kn ) were used to investigate the energetic assimilation of the invasive fish Hemiodus orthonops under different environmental condition of the upper rio Paraná floodplain. Samples were taken in June and September 2013 and 2014. Nutrient content was determined for sediment. The diet was combined in the Food Index (IAi%), ED was expressed in Kcal/g of dry weight and Kn was calculated by: Kn = Wt/We, where Wt is the total weight and We the expected weight. Detritus/sediment prevailed in the stomachs of specimens from Ivinhema and Baia, while Algae was the main item in Paraná, reflecting the resource availability. ED and Kn from Ivinhema specimens were the greatest, consequence of the quality of food and lower spent on searching and handling food. The Paraná specimens showed lower ED values, but higher Kn values, due to algae consumption, a nutrient-rich resource. Baia presented high aluminum concentration on the sediment and the lower pH values, which contribute to reduce the nutritional value of the detritus and the ED and Kn values of their specimens. In conclusion, H.orthonops is capable to take advantage of the resources availability in the different environments, ensuring their establishment.

Selective Doping of 4H-SiC by Aluminum/Boron Co-diffusion

ABSTRACTBased upon graphite mask, selective aluminum/boron doping of SiC by thermal diffusion has been successfully realized in a temperature range of 1800 to 2100°C. Secondary ion mass spectrometry (SIMS) was used to identify the doping profiles, which showed very high aluminum concentration (5×1019 cm−3) near the surface and linearly graded boron profile up to several micrometers in depth. Hall-effect measurement was also employed to obtain the carrier concentration, which showed more than 1019 cm−3 carrier concentration at room temperature. Cathodoluminescence (CL) image clearly illustrated the locally diffused pattern. In addition, planar p-n diodes based upon this technique were fabricated and current-voltage (I-V) characteristics were measured. Excellent rectification property has been obtained. Built-in voltage of 2.9 V in the formed p-n junction was obtained by capacitance-voltage (C-V) measurement.