Tuesday, 21 January 2014

Determination of carrier concentration dependent electron effective mass and scattering time of n-ZnO thin film by terahertz time domain spectroscopy

J. Tang1,2, L. Y. Deng1, C. B. Tay1,2, X. H. Zhang3, J. W. Chai3, H. Qin4, H. W. Liu5, T. Venkatesan2 and S. J. Chua1,2,3,a)


We demonstrated a novel and widely accessible method for determining the electron effective mass and scattering time of ZnO films with different carrier concentrations by combiningterahertz time-domain spectroscopy with Hall measurement. The terahertz time domain spectroscopy (THz-TDS) transmission spectra (0.1–2THz) were well described by Drude model. It is found that electron effective mass varied from 0.23to 0.26as the electron concentration changes from 5.9 × 1017 cm−3 to 4.0 × 1019 cm−3. The carrier concentrationdependent characteristic is ascribed to the non-parabolicity of conduction band. Free carrier localization mechanism explained the discrepancy in mobilities obtained from THz-TDS and Hall measurements.

This study was performed using TeraView's TPS Spectra 3000 system. (TeraView, Cambridge, UK)

Full Article: http://scitation.aip.org/content/aip/journal/jap/115/3/10.1063/1.4861421