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We report the determination of free-electron concentration and mobility of free-standing GaN nanowires (NWs) by line shape analysis of the coupled longitudinal optical phonon-plasmon Raman modes (L+). The E2high phonon mode at 566.9 cm−1 with a sharp linewidth of 2.8 cm−1 indicates strain free NWs with high crystalline perfection. The lattice temperature of the NWs was varied between 313 and 472 K by varying the excitation laser beam power. For unintentionally doped samples at room temperature, an average electron concentration and mobility of strain free NWs were found to be ∼2×1017 cm−3 and 460 cm2/V s, respectively. We have shown that the electron concentration does not change significantly over a temperature range between 313 and 472 K. The electron mobility decreases at high temperatures, in agreement with literature data for compact layers. For Si-doped NWs, the L+ phonon …
American Institute of Physics
Publication date: 
15 Jun 2009

K Jeganathan, RK Debnath, R Meijers, T Stoica, R Calarco, D Grützmacher, H Lüth

Biblio References: 
Volume: 105 Issue: 12 Pages: 123707
Journal of applied physics