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Ultrafast Hot Carrier Dynamics in GaN and Its Impact on the Efficiency Droop

Journal Article · · Nano Letters
 [1];  [2];  [2]
  1. Department of Applied Physics and Materials Science, Steele Laboratory, California Institute of Technology, Pasadena, California 91125, United States; DOE/OSTI
  2. Department of Applied Physics and Materials Science, Steele Laboratory, California Institute of Technology, Pasadena, California 91125, United States
GaN is a key material for lighting technology. Yet, the carrier transport and ultrafast dynamics that are central in GaN light-emitting devices are not completely understood. We present first-principles calculations of carrier dynamics in GaN, focusing on electron–phonon (e-ph) scattering and the cooling and nanoscale dynamics of hot carriers. We find that e-ph scattering is significantly faster for holes compared to electrons and that for hot carriers with an initial 0.5–1 eV excess energy, holes take a significantly shorter time (~0.1 ps) to relax to the band edge compared to electrons, which take ~1 ps. The asymmetry in the hot carrier dynamics is shown to originate from the valence band degeneracy, the heavier effective mass of holes compared to electrons, and the details of the coupling to different phonon modes in the valence and conduction bands. We show that the slow cooling of hot electrons and their long ballistic mean free paths (over 3 nm at room temperature) are a possible cause of efficiency droop in GaN light-emitting diodes. Taken together, our work sheds light on the ultrafast dynamics of hot carriers in GaN and the nanoscale origin of efficiency droop.
Research Organization:
California Inst. of Technology (CalTech), Pasadena, CA (United States); The Joint Center for Artificial Photosynthesis, Pasadena, CA (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE Office of Science (SC)
Grant/Contract Number:
AC02-05CH11231; SC0004993
OSTI ID:
1418563
Alternate ID(s):
OSTI ID: 1467614
Journal Information:
Nano Letters, Journal Name: Nano Letters Journal Issue: 8 Vol. 17; ISSN 1530-6984
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

References (51)

Group III-nitride lasers: a materials perspective journal September 2011
Hot electron relaxation time in GaN journal February 1999
Microscopic theory of electron-phonon interaction in insulators or semiconductors journal January 1976
Quasiparticle band structure of AlN and GaN journal October 1993
First-principles calculations of indirect Auger recombination in nitride semiconductors text January 2014
Group III-nitride lasers: a materials perspective journal September 2011
wannier90: A tool for obtaining maximally-localised Wannier functions journal May 2008
EPW: A program for calculating the electron–phonon coupling using maximally localized Wannier functions journal December 2010
An updated version of wannier90: A tool for obtaining maximally-localised Wannier functions journal August 2014
Exciton Radiative Lifetimes in Two-Dimensional Transition Metal Dichalcogenides journal March 2015
Theory and computation of hot carriers generated by surface plasmon polaritons in noble metals journal June 2015
Prospects for LED lighting journal April 2009
Droop improvement in high current range on PSS-LEDs journal January 2011
Hot hole relaxation dynamics in p -GaN journal August 2000
Energy relaxation by hot electrons in n-GaN epilayers journal January 2001
Optical study of hot electron transport in GaN: Signatures of the hot-phonon effect journal January 2006
Time-resolved intervalley transitions in GaN single crystals journal February 2007
Blue-emitting InGaN–GaN double-heterostructure light-emitting diodes reaching maximum quantum efficiency above 200A∕cm2 journal December 2007
Evidence of hot electrons generated from an AlN∕GaN high electron mobility transistor journal January 2008
Hot electron effects on efficiency degradation in InGaN light emitting diodes and designs to mitigate them journal August 2010
Indirect Auger recombination as a cause of efficiency droop in nitride light-emitting diodes journal April 2011
Temperature-dependence of the internal efficiency droop in GaN-based diodes journal October 2011
Efficiency droop in InGaN/GaN blue light-emitting diodes: Physical mechanisms and remedies journal August 2013
Measurement of the hot electron mean free path and the momentum relaxation rate in GaN journal December 2014
Ab initio study of hot electrons in GaAs journal April 2015
Electrons in lattice fields journal July 1954
Current status and scope of gallium nitride-based vertical transistors for high-power electronics application journal June 2013
Energy and momentum relaxation of hot electrons in GaN/AlGaN journal March 2002
QUANTUM ESPRESSO: a modular and open-source software project for quantum simulations of materials journal September 2009
Quantum Processes in Semiconductors book January 2013
Microscopic theory of electron-phonon interaction in insulators or semiconductors journal January 1976
Self-interaction correction to density-functional approximations for many-electron systems journal May 1981
Nonlinear ionic pseudopotentials in spin-density-functional calculations journal August 1982
Electron correlation in semiconductors and insulators: Band gaps and quasiparticle energies journal October 1986
Efficient pseudopotentials for plane-wave calculations journal January 1991
Quasiparticle band structure of AlN and GaN journal October 1993
Spectral and Fermi surface properties from Wannier interpolation journal May 2007
Electron-phonon interaction using Wannier functions journal October 2007
First-principles calculations of indirect Auger recombination in nitride semiconductors journal July 2015
Ab initio electronic relaxation times and transport in noble metals journal October 2016
Ab initio electron mobility and polar phonon scattering in GaAs journal November 2016
Ab Initio Study of Hot Carriers in the First Picosecond after Sunlight Absorption in Silicon journal June 2014
Fröhlich Electron-Phonon Vertex from First Principles journal October 2015
Phonons and related crystal properties from density-functional perturbation theory journal July 2001
Maximally localized Wannier functions: Theory and applications journal October 2012
Experimental Demonstration of III-Nitride Hot-Electron Transistor With GaN Base journal September 2011
Reliability of GaN High-Electron-Mobility Transistors: State of the Art and Perspectives journal June 2008
First-principles dynamics of electrons and phonons* journal November 2016
Power-switching applications beyond silicon: Status and future prospects of SiC and GaN devices journal May 2015
A roadmap for future wide bandgap semiconductor power electronics journal May 2015
Condensed Matter in a Nutshell book January 2011

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Kinetically controlled transition from 2D nanostructured films to 3D multifaceted InN nanocrystals on GaN(0001) journal January 2018
Dependence of hot electron transfer on surface coverage and adsorbate species at semiconductor–molecule interfaces journal January 2018
Hot electron relaxation dynamics in semiconductors: assessing the strength of the electron–phonon coupling from the theoretical and experimental viewpoints journal August 2018
Precise radiative lifetimes in bulk crystals from first principles: the case of wurtzite gallium nitride journal November 2019
Determination of size dependent carrier capture in InGaN/GaN quantum nanowires by femto-second transient absorption spectroscopy: effect of optical phonon, electron–electron scattering and diffusion journal February 2019
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Efficient ab initio calculations of electron-defect scattering and defect-limited carrier mobility journal March 2019
Electron-phonon coupling and hot electron thermalization in titanium nitride journal November 2019
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Resonance Raman Spectroscopy of Mn-Mgk Cation Complexes in GaN journal May 2019
Ab Initio Electron-Phonon Interactions Using Atomic Orbital Wavefunctions text January 2018
First-principles calculations of charge carrier mobility and conductivity in bulk semiconductors and two-dimensional materials text January 2019
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