Engineering topics

Ber, B Ya

Publications and source records attributed to Ber, B Ya.

4 records

DOE OSTI2012

Silicon photodiode with selective Zr/Si coating for extreme ultraviolet spectral range

The procedure of manufacturing silicon photodiodes with an integrated Zr/Si filter for extreme ultraviolet (EUV) spectral range is developed. A setup for measuring the sensitivity profile of detectors with spatial resolution better than 100 {mu}m is fabricated. The optical properties of silicon photodiodes in the EUV and visible spectral ranges are investigated. Some characteristics of SPD-100UV diodes with Zr/Si coating and without it, as well as of AXUV-100 diodes, are compared. In all types of detectors a narrow region beyond the operating aperture is found to be sensitive to the visible light. (photodetectors)

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2011

Electrochemical capacitance-voltage profiling of the free-carrier concentration in HEMT heterostructures based on InGaAs/AlGaAs/GaAs compounds

The depth distribution of free carriers over the HEMT structures with quantum-well layers is studied by electrochemical capacitance-voltage profiling. It is shown that the actual distribution of the concentration of free carriers and their energy spectrum in the HEMT structure channel can be obtained by numerical simulation of the results of profiling based on the self-consistent solution of one-dimensional Schroedinger and Poisson equations.

36 MATERIALS SCIENCE↗

DOE OSTI2011

Evolution of the deformation state and composition as a result of changes in the number of quantum wells in multilayered InGaN/GaN structures

The methods of high-resolution X-ray diffraction have been used to study the multilayered structures in an In{sub x}Ga{sub 1-x}N/GaN system grown by the method of metal-organic chemical-vapor deposition. A correlation between the strain state (relaxation) of the system, the indium content within quantum wells, the ratio of the barrier/well thicknesses, and the number of quantum wells in the active superlattice is established. It is shown that partial relaxation is observed even in a structure with one quantum well. The results we obtained indicate that the relaxation processes are bound to appreciably affect the optical characteristics of devices.

36 MATERIALS SCIENCE↗

DOE OSTI2011

Effect of the silicon doping level and features of nanostructural arrangement on decrease in external quantum efficiency in InGaN/GaN light-emitting diodes with increasing current

A comprehensive study of blue light-emitting diodes based on quantum-well InGaN/GaN structures with external quantum efficiencies {eta} of up to 40% has been carried out. It is shown that, in the general case, the manner in which the efficiency depends on the current density j is determined by the competition of contributions to the radiative recombination of localized and delocalized carriers. The contribution of the latter grows with worsening structural organization of the nanomaterial, increasing temperature and drive current, and decreasing width of the depleted layer in the active region (under zero bias). The steepest efficiency droop relative to the maximum value (by up to a factor of 2 at j Almost-Equal-To 50 A cm{sup -2}) is observed in the case of heavy doping of the n{sup +}-region (to 10{sup 19} cm{sup -3}) and upon appearance of compensated layers in the active or p{sup +}-region. At j > 50 A cm{sup -2}, the contribution of delocalized carriers is predominant and the current dependences of efficiency are of uniform type, approximated with {eta}(j) {proportional_to} j{sup -b}, where 0.2 < b < 0.3.

36 MATERIALS SCIENCE↗