Metallic Transport and Anderson Localization on In Atomic Layers on Silicon

Metallic temperature dependence of electrical resistance have not been observed except extremely limited number of examples[1] below 100K in atomic-scale low-dimensional metal systems due to Anderson localization. Si(111)-$\sqrt 7 \times \sqrt 3 $-In surface reconstruction consist of 1.2 ML In atoms. According to ARPES study, the surface is 2D metal with the large Fermi wave number (k$_{F}$=14nm$^{-1})$ and the large electron density (4.6$\times $10$^{14}$eV$^{-1}$cm$^{-2})$, leading to a low resistance [2]. By using variable-temperature micro-four-point probe method [3], low resistance and metallic transport was found down to 10 K. It is quantitatively explained by the ARPES result by using Boltzmann equation $R_{2D} =\frac{4\pi ^2\lambda m^\ast }{e^2\hbar k_F^2 }k_B T$. By introducing defect, it shows semiconducting temperature dependence of variable range hopping due to Anderson localization. [1]K. Lee, \textit{et al}. , Nature \textbf{441}, 65 (2006). [2]E. Rotenberg, \textit{et al}. , Phys. Rev. Lett. \textbf{91}, 246404 (2003). [3]T. Tanikawa,\textit{ et al}. , e-J. Surf. Sci. Nanotech. \textbf{1}, 50 (2003)