Critical Temperature to Dielectric Degradation of Printed Circuit Board
Dielectric degradation of printed circuit board based on the thermal properties in an open-air environment was investigated. With increase of the temperature, the copper electrodes were oxidized from Cu 2O to CuO; the base material of epoxy laminate was thermally affected to the change of molecular structure and degradation of dielectric properties. With increase of the temperature, the capacitance and surface resistance decreased, the thermal stimulated current increased and showed a valley value near 450 K and a peak value near 490 K
Thermally stimulated discharge currents in high temperature dielectrics
The measurement of TSD (thermally stimulated discharge) currents in Nomex is reported. The TSD currents were measured by heating the sample at a uniform rate. Both the temperature and the current were measured using a strip chart recorder having a sensitivity of 2 mu V/mm and 10/sup -14/ A/mm, respectively. Detailed results are presented.<<ETX>>
Photoreflectance characterization of vanadium-doped GaAs layers grown by metalorganic vapor phase epitaxy
Abstract We characterized the vanadium-doped (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy. The conductivity of the samples is checked by the Hall effect measurements, and it is n type with electrons concentration ranging from 2×10 13 to 2×10 17  cm −3 . We used the photoreflectance technique (PR) to study the effect of vanadium doping on the optical properties of GaAs. Our experimental results show that the built-in electric field F and the broadening parameter Γ 0 increase with V-doping concentration. Furthermore, the temperature dependence of the built-in electric field and the broadening parameter of GaAs:V samples have been investigated by PR. It has been observed that these parameters increase with increasing temperature. The decrease of the built-in electric field with decreasing temperature is due to the photovoltage effect.We characterized the vanadium-doped GaAs (GaAs:V) layers grown on GaAs substrate by metalorganic vapor phase epitaxy.