Impact of Point Defects on the Luminescence Properties of (Al,Ga)N

Threading dislocations (TDs) in (Al,In,Ga)N semiconductors are known to affect the luminescence efficiency of near-band-edge (NBE) emissions in bulk films and quantum structures. However, the principal role of point defects such as vacancies on the luminescent properties has not been fully understood. In this article, impacts of point defects on the luminescence quantum efficiency of NBE emissions and on the intensity of deep emission bands will be described, based on the results of steady-state and time-resolved photoluminescence (TRPL) and positron annihilation measurements. The room temperature nonradiative lifetime (τNR) of the NBE excitonic photoluminescence (PL) peak in polar (0001) and (000-1) , nonpolar (11-20) and (10-10), and zincblende (001) GaN layers prepared by various growth techniques was shown to increase with the decrease in concentration or size of Ga vacancies (VGa) and with the decrease in gross concentration of point defects including complexes, leading to an increase in the NBE PL intensity. As the edge TD density decreased, the concentration or size of VGa tended to decrease and τNR tended to increase. However, there existed remarkable exceptions. The results indicate that the nonradiative recombination process is governed not by single point defects, but by certain defects introduced with the incorporation of VGa, such as VGa-defect complexes. Similar relations were found in AlxGa1-xN alloy films grown by metalorganic vapor phase epitaxy: i. e. τNR at room temperature increased with the decrease in the concentration of cation vacancies (VIII) and with the decrease in gross concentration of point defects. In addition to nonradiative processes, the VIII concentration was found to correlate with the intensity ratio of characteristic deep emission band to the NBE emission (Ideep/INBE). For example, Ideep/INBE at low temperature for the deep emission bands at 4.6, 3.8, and 3.1 eV of AlN epilayers grown by NH3-source molecular beam epitaxy had a linear correlation with the concentration or size of Al vacancies (VAl). Since the relative intensities of 3.1 eV and 3.8 eV bands increased remarkably with lowering the supply ratio of NH3 to Al (V/III ratio) and growth temperature (Tg), they were assigned to originate from VAl-O as well as VAl-shallow donor complexes. The VAl concentration could be decreased by adjusting the V/III ratio and Tg. In the case of AlxGa1-xN alloys, the concentration or size of VIII and Ideep/INBE at 300 K increased simultaneously with the increase in x up to approximately 0.7. Similar to the case for GaN and AlN, the deep emission band was assigned as being due to the emission involving VIII-O complexes.

[1]  S. Denbaars,et al.  Impact of strain on free-exciton resonance energies in wurtzite AlN , 2007 .

[2]  A. Uedono,et al.  Relation between Al vacancies and deep emission bands in AlN epitaxial films grown by NH3-source molecular beam epitaxy , 2007 .

[3]  J. Bläsing,et al.  MOVPE growth of high-quality AlN , 2006 .

[4]  A. Uedono,et al.  Origin of defect-insensitive emission probability in In-containing (Al,In,Ga)N alloy semiconductors , 2006, Nature materials.

[5]  Y. Taniyasu,et al.  An aluminium nitride light-emitting diode with a wavelength of 210 nanometres , 2006, Nature.

[6]  O. Ambacher,et al.  Luminescence properties of highly Si-doped AlN , 2006 .

[7]  P. Hinze,et al.  Suppression of nonradiative recombination by V-shaped pits in GaInN/GaN quantum wells produces a large increase in the light emission efficiency. , 2005, Physical review letters.

[8]  K. B. Nam,et al.  Deep impurity transitions involving cation vacancies and complexes in AlGaN alloys , 2005 .

[9]  G. A. Slack,et al.  Excitonic structure of bulk AlN from optical reflectivity and cathodoluminescence measurements , 2005 .

[10]  James S. Speck,et al.  Limiting factors of room-temperature nonradiative photoluminescence lifetime in polar and nonpolar GaN studied by time-resolved photoluminescence and slow positron annihilation techniques , 2005 .

[11]  A. Uedono,et al.  Reduction of point defect density in cubic GaN epilayers on (001) GaAs substrates using AlxGa1-xN/GaN superlattice underlayers , 2004 .

[12]  Wladek Walukiewicz,et al.  Optical properties and electronic structure of InN and In-rich group III-nitride alloys , 2004 .

[13]  G. A. Slack,et al.  Near-bandedge cathodoluminescence of an AlN homoepitaxial film , 2004 .

[14]  C. Walle,et al.  First-principles calculations for defects and impurities: Applications to III-nitrides , 2004 .

[15]  A. Zunger,et al.  Type I to type II transition at the interface between random and ordered domains of AlxGa1−xN alloys , 2004 .

[16]  A. Uedono,et al.  Radiative and nonradiative processes in strain-free AlxGa1−xN films studied by time-resolved photoluminescence and positron annihilation techniques , 2004 .

[17]  Colin J. Humphreys,et al.  Electron-beam-induced strain within InGaN quantum wells: False indium “cluster” detection in the transmission electron microscope , 2003 .

[18]  Suhuai Wei,et al.  Band structure and fundamental optical transitions in wurtzite AlN , 2003 .

[19]  Fernando Ponce,et al.  Microstructure and electronic properties of InGaN alloys , 2003 .

[20]  K. Hiramatsu,et al.  High‐quality AlN epitaxial films on (0001)‐faced sapphire and 6H‐SiC substrate , 2003 .

[21]  Shuji Nakamura,et al.  Recombination dynamics of localized excitons in cubic InxGa1−xN/GaN multiple quantum wells grown by radio frequency molecular beam epitaxy on 3C–SiC substrate , 2003 .

[22]  P. Lefebvre,et al.  Donor-acceptor-like behavior of electron-hole pair recombinations in low-dimensional (Ga,In)N/GaN systems , 2003 .

[23]  G. A. Slack,et al.  Some effects of oxygen impurities on AlN and GaN , 2002 .

[24]  Maria R. Correia,et al.  Structural and optical properties of InGaN/GaN layers close to the critical layer thickness , 2002 .

[25]  C. Stampfl,et al.  Theoretical investigation of native defects, impurities, and complexes in aluminum nitride , 2002 .

[26]  Paul R. C. Kent,et al.  Carrier localization and the origin of luminescence in cubic InGaN alloys , 2001 .

[27]  A. F. Wright.  Interaction of hydrogen with gallium vacancies in wurtzite GaN , 2001 .

[28]  Takashi Mukai,et al.  Study of defects in GaN grown by the two-flow metalorganic chemical vapor deposition technique using monoenergetic positron beams , 2001 .

[29]  S. Kamiyama,et al.  Low-temperature-deposited AlGaN interlayer for improvement of AlGaN/GaN heterostructure , 2001 .

[30]  M. Reiche,et al.  Nitride semiconductors free of electrostatic fields for efficient white light-emitting diodes , 2000, Nature.

[31]  J. B. Lam,et al.  Dynamics of anomalous optical transitions in Al x Ga 1 − x N alloys , 2000 .

[32]  Jun Li,et al.  Time-resolved photoluminescence studies of AlxGa1−xN alloys , 2000 .

[33]  M. Skowronski,et al.  Erratum: ``Evidence for localized Si-donor state and its DX-like properties in AlGaN'' [Appl. Phys. Lett. 74, 3833 (1999)] , 1999 .

[34]  J. Im,et al.  Optical Properties of Nitride Quantum Wells: How to Separate Fluctuations and Polarization Field Effects , 1999 .

[35]  L. Coldren,et al.  Optical properties of InGaN quantum wells , 1999 .

[36]  Shuji Nakamura,et al.  Dimensionality of excitons in laser-diode structures composed of In x Ga 1-x N multiple quantum wells , 1999 .

[37]  Alex Zunger,et al.  Resonant hole localization and anomalous optical bowing in InGaN alloys , 1999 .

[38]  John E. Bowers,et al.  Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth , 1999 .

[39]  H. Amano,et al.  Piezoelectric Stark-like Ladder in GaN/GaInN/GaN Heterostructures , 1999 .

[40]  Ellen B. Stechel,et al.  Charge accumulation at a threading edge dislocation in gallium nitride , 1999 .

[41]  Wei Yang,et al.  Room-temperature deep-ultraviolet-stimulated emission from AlxGa1−xN thin films grown on sapphire , 1999 .

[42]  Robert W. Martin,et al.  Origin of Luminescence from InGaN Diodes , 1999 .

[43]  Ulrike Grossner,et al.  The effect of doping and growth stoichiometry on the core structure of a threading edge dislocation in GaN , 1998 .

[44]  Chris G. Van de Walle,et al.  Doping of AlxGa1−xN , 1998 .

[45]  James S. Speck,et al.  STRUCTURAL ORIGIN OF V-DEFECTS AND CORRELATION WITH LOCALIZED EXCITONIC CENTERS IN INGAN/GAN MULTIPLE QUANTUM WELLS , 1998 .

[46]  Michael Kneissl,et al.  Metastability of Oxygen Donors in AlGaN , 1998 .

[47]  Satoshi Kurai,et al.  Direct Evidence that Dislocations are Non-Radiative Recombination Centers in GaN , 1998 .

[48]  Kazumi Wada,et al.  Spatially resolved cathodoluminescence spectra of InGaN quantum wells , 1997 .

[49]  L. Dobrzyński,et al.  Observation Of Native Ga Vacancies In Gan By Positron Annihilation , 1997 .

[50]  Isamu Akasaki,et al.  Crystal Growth and Conductivity Control of Group III Nitride Semiconductors and Their Application to Short Wavelength Light Emitters , 1997 .

[51]  Shuji Nakamura,et al.  Atomic Scale Indium Distribution in a GaN/In0.43Ga0.57N/Al0.1Ga0.9N Quantum Well Structure , 1997 .

[52]  D. Bour,et al.  Nitride-based semiconductors for blue and green light-emitting devices , 1997, Nature.

[53]  Shuji Nakamura,et al.  Role of self-formed InGaN quantum dots for exciton localization in the purple laser diode emitting at 420 nm , 1997 .

[54]  E. Haller,et al.  PRESSURE INDUCED DEEP GAP STATE OF OXYGEN IN GAN , 1997 .

[55]  S. Dannefaer,et al.  Positron line-shape parameters and lifetimes for semiconductors: Systematics and temperature effects , 1997 .

[56]  S. Nakamura,et al.  Spontaneous emission of localized excitons in InGaN single and multiquantum well structures , 1996 .

[57]  R. Nieminen,et al.  Ab initio study of oxygen point defects in GaAs, GaN, and AlN. , 1996, Physical review. B, Condensed matter.

[58]  Jörg Neugebauer,et al.  Gallium vacancies and the yellow luminescence in GaN , 1996 .

[59]  S. Nakamura,et al.  Excitonic emissions from hexagonal GaN epitaxial layers , 1996 .

[60]  A. C. Kruseman,et al.  VEPFIT applied to depth profiling problems , 1995 .

[61]  Van de Walle CG,et al.  Atomic geometry and electronic structure of native defects in GaN. , 1994, Physical review. B, Condensed matter.

[62]  J. A. Van Vechten,et al.  Quantum Dielectric Theory of Electronegativity in Covalent Systems. III. Pressure-Temperature Phase Diagrams, Heats of Mixing, and Distribution Coefficients , 1973 .

[63]  C. G Dunn,et al.  Comparison of dislocation densities of primary and secondary recrystallization grains of Si-Fe , 1957 .

[64]  S. Denbaars,et al.  Impact of Internal Electric Field and Localization Effect on Quantum Well Excitons in AlGaN/GaN/InGaN Light Emitting Diodes , 2001 .

[65]  A. Uedono,et al.  Impact of growth polar direction on the optical properties of GaN grown by metalorganic vapor phase epitaxy , 2001 .

[66]  R. Krause-Rehberg,et al.  Positron Annihilation in Semiconductors , 1999 .

[67]  M. Manfredi,et al.  POSITRON ANNIHILATION IN SEMICONDUCTORS. , 1968 .