Nitride semiconductors are the key materials for solid-state lighting. Point defects may act as compensating centers, charge traps, or radiative or nonradiative recombination centers. Unintentional impurities often play an equally important role; for instance, carbon that is unavoidably incorporated during metal-organic chemical vapor deposition can act as a source of yellow luminescence. Theoretical advances now enable us to calculate the energetics as well as electronic and optical properties of point defects with unprecedented accuracy. We have developed a first-principles methodology to determine nonradiative carrier capture coefficients. Accurate calculations of electron-phonon coupling, combined with results for defect formation energies and charge-state transition levels, enable the calculation of nonradiative capture rates for electrons and holes and the evaluation of Shockley-Read-Hall coefficients. This approach allows us to identify specific defects that play a key role in limiting the efficiency of nitride semiconductor devices.
---Work performed in collaboration with A. Alkauskas, C. Dreyer, A. Janotti, J. Lyons, J. Shen, J. Speck, and D. Wickramaratne, and supported by DOE and NSF.
Chris G. Van de Walle, "Impact of defects on efficiency of light emitters (Conference Presentation)," Proc. SPIE 10554, Light-Emitting Diodes: Materials, Devices, and Applications for Solid State Lighting XXII, 105540A (Presented at SPIE OPTO: January 29, 2018; Published: 14 March 2018); https://doi.org/10.1117/12.2280166.5751478523001.
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