Abstract
Blue light emitting diodes (LEDs) based on an AlGaN/GaN/AlGaN double heterojunction structure were electrically characterized as a function of temperature. Current-voltage (I–V), capacitance-voltage (C–V) and reverse recovery storage time measurements were conducted at temperatures in the range between −8° and 75° C. Capacitance-voltage measurements as a function frequency (20 Hz–1 MHz) and electroluminescence study at room temperature were also performed. It was observed that the diode turn-on voltage decreased with increasing temperature, however, reverse leakage currents monitored at −1, −5 and −10 V showed only a slight increase with increasing temperature. The concentration of deep states and their position in the bandgap, as extracted from logarithmic plots of the forward characteristics, were not influenced by the measurement temperature. Recombination lifetimes, as obtained from experimentally determined reverse recovery storage times, remained constant over the range of temperature considered. A higher value of diode capacitance was observed at low measurement frequencies (20 Hz–1 kHz), gradually dropping to a lower value over a frequency range between (1 kHz–100 kHz) and remained constant from 100 kHz to 1 MHz. A loss peak centered about 10 kHz was observed in the corresponding plot of gm/ω as a function of frequency, f. The position of the peak in the gm/ω - frequency (f) plot and dC/dω(for f in the range 1 kHz–100 kHz ), yielded a concentration of deep-states of approximately 2.2 × 1015/cm3, located at 0.39 eV above the valence band edge.
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Acknowledgements
Research reported here was partially sponsored by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, partially funded by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy under Contract No. DE-AC0500OR22725 and in part by an appointment (K. Das) to the Oak Ridge National Laboratory/Oak Ridge Associated Universities Historically Black Colleges and Universities and Minority Education Institutions Summer Faculty Research Program. Partial support was also provided by the Department of Electrical Engineering, Tuskegee University.
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Murthy, M., Kamto, A., Awaah, M.A. et al. Electrical Characterization of Blue Light Emitting Diodes as a Function of Temperature. MRS Online Proceedings Library 892, 1208 (2005). https://doi.org/10.1557/PROC-0892-FF12-08
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DOI: https://doi.org/10.1557/PROC-0892-FF12-08