23 research outputs found
MBE growth of high electron mobility 2DEGs in AlGaN/GaN heterostructures controlled by RHEED
No full textWe have grown 2DEG AlGaN/GaN heterostructures by molecular beam epitaxy (MBE) with electron mobilities up to 21500 cm2V−1s−1 at 2 K. In-situ RHEED was applied to optimize different aspects of Ga-rich growth. This paper gives a compact overview of the experimental key aspects that significantly affect the low temperature electron mobility in AlGaN/GaN heterostructures. Growth at the transition towards Ga droplet formation produced the best results. A quantitative analysis of the magnetoresistance confirmes scattering at dislocations as the dominant scattering process at low temperature
Broxtermann (Birth, 1895-04-01)
No full textAddress: Dalton & Flint2189/Pg. 56/1895/F W/Cinti./Cinti./Mrs. D. BuetherOriginal record filed in drawer labeled 'BROWN,G.-BRUN'
Polarity dependent strongly inhomogeneous In-incorporation in GaN nanocolumns
No full textIn this work, GaN/InGaN/GaN nanocolumns (NCs) have been grown by molecular beam epitaxy. Selective area growth (SAG) and self-organized growth (SOG) were performed simultaneously in patterned and unpatterned regions of the same substrate, respectively. The resulting structures show different tip morphologies and structural properties due to the different polarity along the growth direction, namely Ga-polar with r-plane faceted tips for the SAG NCs and N-polar with c-plane top facet for the SOG ones. When growing Ga-polar GaN/InGaN NCs, no indium is incorporated at a substrate temperature of °C. Rather, indium incorporation takes place under the same growth conditions on the N-polar NCs. The In-incorporation is investigated by means of nano x-ray fluorescence and diffraction, high-angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy
Method to Predict and Optimize Charge Sensitivity of Ungated AlGaN/GaN HEMT-Based Ion Sensor Without Use of Reference Electrode
No full textIn this paper, we report on a methodology for theoretical prediction and optimization of charge sensitivity for ungated AlGaN/GaN high electron mobility transistorbased ion sensors operated in the reference electrode free configuration. We have performed numerical simulations of device sensitivity, specifically the change in channel electron concentration with the change in surface potential, for different Al mole fractions and AlGaN thicknesses. These results can be used for device optimization, signal analysis, and sensor calibration purposes. To validate the model, six ungated AlGaN/GaN transistor-based devices of different Al mole fractions and AlGaN thicknesses were fabricated. These devices were exposed to KOH solutions with different pH values, and the voltage change at the gate area was indirectly measured as a function of ionic concentration. The gain in conductivity across the measured range of pH values was experimentally extracted for each device and closely matched the sensitivity predicted by simulation
Broxtermann, Herbert J. (Death, 1906-08-18)
No full textAddress: Flint & Dalton St.Age at death: 2 yrs.298/Pg 105/1906/M W S/City/Dr. A. P. Reneker M. D./Busse & Borgmann/St. Mary'sOriginal record filed in drawer labeled 'BROWN,G.-BRUN'
Broxtermann, Anna (Birth, 1905-07-31)
No full textAddress: S. E. CorDalton & Flint3322/Pg 78/1905/F W/Cinti/Ind./Mrs. D. BuetherOriginal record filed in drawer labeled 'BROWN,G.-BRUN'
Mercury Free UV Lamp for Disinfection and Purification of Drinking, Process, and Waste Water – An Approach to assessing its Innovation Potential and Possible Market Entry Strategies
No full textUltraviolet radiation sources found many application areas in science and technology. They play an important role within several markets worldwide today. One of these markets is disinfection and photochemical purification of water which has been a growing market for many decades. At the moment low pressure mercury discharge lamps are the state of the art technology. Although they have been developed towards an impressive maturity level, they still show many drawbacks as e.g. strong temperature dependence. Therefore, this paper is dedicated to a mercury free alternative radiation source for this market, namely so called phosphor converted excimer discharge lamps. They are in the centre of present R&D activities, since they offer several advantages compared to the mercury discharge lamps such as very little temperature sensitivity, a high customisability of the emission spectrum, a large form factor, and instant full radiation power after they have been switched on. A brief description of the technology of phosphor converted excimer lamps will be sketched and furthermore their potential as a possible game changer for water disinfection and photochemical water purification market areas will be highlighted
Cathodoluminescence and Photoluminescence of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+
No full text© Copyright 2017 The Author(s). Herein we describe the synthesis, characterization, and cathodoluminescence of the UV emitting phosphors YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+, and YPO4:Bi3+. These photoluminescent UV phosphors exhibited strong luminescence in the UV part of the electromagnetic spectrum when excited by electron bombardment. Spectra have been recorded between 210 and 650 nm at electron beam energies of 5, 10 and 15 keV. The energy efficiencies of YPO4:Pr3+, Y2SiO5:Pr3+, YBO3:Pr3+ and YPO4:Bi3+ in the UV range were 9.2%, 2.7%, 5.1%, and 7.2%, respectively at 15 keV. UV photoluminescence measurements were conducted using 160 nm excitation generated by combining a VUV monochromator with a deuterium lamp.We are grateful to the German ministry for research and education (BMBF) and to the Foundation of the German economy for generous financial support. We are also grateful to the EPSRC and Technology Strategy Board (TSB) for funding the PURPOSE (TP11/MFE/6/1/AA129F; EP-SRC TS/G000271/1) and CONVERTED (JeS no. TS/1003053/1), PRISM (EP/N508974/1) and FAB3D programs. We are finally grateful to the TSB for funding the CONVERT program
