Carrier density imaging of lateral epitaxially overgrown GaN using scanning confocal Raman microscopy

Matthews, Manyalibo J.; Hsu, J. W. P.; Gu, Shulin; Kuech, T. F.
November 2001
Applied Physics Letters;11/5/2001, Vol. 79 Issue 19, p3086
Academic Journal
GaN thin films, grown by the lateral epitaxial overgrowth (LEO) method, are studied by scanning confocal Raman microscopy. By measuring changes in coupled longitudinal-optical phonon–plasmon frequencies and using a standard harmonic oscillator dielectric function, detailed images of carrier density could be formed. Carrier concentrations are extremely high (∼10[sup 20] cm[sup -3]) immediately above SiO[sub x] mask layers and decrease abruptly when the SiO[sub x] mask are not directly exposed to the growth surface, implying that SiO[sub x] masks are the source of dopants. Images of intergrated E[sub 1] longitudinal-optical phonon intensities could be compared with free-carrier images and showed a clear anticorrelation throughout the LEO structure.© 2001 American Institute of Physics.


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