Micro-Raman and photoluminescence studies of neutron-irradiated gallium nitride epilayers

GaN epilayers grown on sapphire substrate were irradiated with various dosages of neutrons and were characterized using Micro-Raman and photoluminescence. It was found that the A1(LO) peak in the Raman spectra clearly shifted with neutron irradiation dosage. Careful curve fitting of the Raman data was carried out to obtain the carrier concentration which was found to vary with the neutron irradiation dosage. The variation of the full width at half maximum height of the photoluminescence was consistent with the Raman results. The neutron irradiation-induced structural defects (likely to be GeGa) give rise to carrier trap centers which are responsible for the observed reduction in carrier concentration of the irradiated GaN.

[1]  J. Takahashi,et al.  Lattice distortions and the transmuted-Ge related luminescence in neutron-transmutation-doped GaN , 2002 .

[2]  G. L. Pearson,et al.  Gamma‐Radiation Damage in Epitaxial Gallium Arsenide , 1972 .

[3]  Isamu Akasaki,et al.  Deep level defects in n‐type GaN , 1994 .

[4]  F. D. Auret,et al.  Sputter deposition-induced electron traps in epitaxially grown n-GaN , 1999 .

[5]  Jerry Bernholc,et al.  Doping properties of C, Si, and Ge impurities in GaN and AlN , 1997 .

[6]  J. Off,et al.  Raman studies of longitudinal optical phonon–plasmon coupling in GaN layers , 1998 .

[7]  Q. Li,et al.  Shallow optically active structural defect in wurtzite GaN epilayers grown on stepped 4H-SiC substrates , 2003 .

[8]  Wei Wang,et al.  OBSERVATION OF OPTICALLY-ACTIVE METASTABLE DEFECTS IN UNDOPED GAN EPILAYERS , 1998 .

[9]  Jin-Xing Shi,et al.  Influence of different types of threading dislocations on the carrier mobility and photoluminescence in epitaxial GaN , 2002 .

[10]  Ching‐Wu Wang.  Neutron irradiation effect on radio-frequency magnetron-sputtered GaN thin films and Au/GaN Schottky diodes , 2002 .

[11]  Tetsu Kachi,et al.  Raman scattering from LO phonon‐plasmon coupled modes in gallium nitride , 1994 .

[12]  T. Kawakubo,et al.  Depth uniformity of electrical properties and doping limitation in neutron-transmutation-doped semi-insulating GaAs , 1990 .

[13]  Min Xie,et al.  Stress and its effect on optical properties of GaN epilayers grown on Si(111), 6H-SiC(0001), and c-plane sapphire , 2003 .

[14]  M. Coeck,et al.  Defects in neutron transmutation doped silicon studied by positron annihilation lifetime measurements , 2000 .

[15]  Hiroshi Harima,et al.  Raman scattering from anisotropic LO‐phonon–plasmon–coupled mode in n‐type 4H– and 6H–SiC , 1995 .

[16]  M. A. Hernández-Fenollosa,et al.  Observation of Fe-related defects in neutron irradiated semi-insulating InP , 2001 .

[17]  Andreas Hoffmann,et al.  A comparison of the Hall-effect and secondary ion mass spectroscopy on the shallow oxygen donor in unintentionally doped GaN films , 2000 .

[18]  Hiroshi Harima,et al.  TOPICAL REVIEW: Properties of GaN and related compounds studied by means of Raman scattering , 2002 .

[19]  Jinn-Kong Sheu,et al.  Effects of thermal annealing on the indium tin oxide Schottky contacts of n-GaN , 1998 .

[20]  A. Ougouag,et al.  Carrier removal and changes in electrical properties of neutron irradiated GaAs , 1991 .

[21]  A. Cavallini,et al.  Deep levels and irradiation effects in n-GaN , 2000 .