(Color online) (a) Scanning electron microscopy images of pristine GaN NWs used in this study, and (b) representative RT sPL spectra of GaN NWs after different surface treatments.
Statistics of RT-PL results of GaN NWs with different surface conditions. (a) The PL peak energy, (b) the FWHM of the emission band, and (c) the integrated PL intensity normalized to the excitation intensity for different surface modifications. Error bars shown in all graphs are the statistical standard deviations obtained from seven different measured samples.
(Color online) PLE spectra of pristine GaN NWs and MPTMS-GaN NWs with various CMPTMS. The arrow indicates a strong absorption band at 4.6–4.8 eV, correlated with the MPTMS-functionalization. The spectrum corresponding to the pristine GaN NWs has been multiplied by a factor of 8.
(Color online) The representative RT Raman spectra of GaN NWs at different stages. The relative intensity of DARS with respect to the E2 and the FWHM of E2 are shown in the inset graph.
(Color online) Low-temperature (5 K) PL spectra of GaN NWs at different stages. The spectra are normalized to the intensity of the D0X peak.
(Color online) Normalized time-resolved PL spectra of the D0X (3.472 eV) and the Id (3.43 eV). The spectra of the Id are shifted for clarity. Inset: magnified views of the time delay in the 100–500 ps window. The results are plotted with a logarithmic y-axis of intensity decay and a linear x-axis of time delay, as the half-lifetime of excited carriers can be obtained by estimating the slope of the decay curves.
(Color online) Schematic illustration of the proposed surface band bending conditions of the GaNNWs with respect to different surface conditions to explain the observed results: (a) pristine GaN NWs, (b) OH-GaN NWs, and (c) MPTMS-GaN NWs.
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