Extraordinary optoconductance in InSb-Au thin film hybrid structures

Extraordinary optoconductance (EOC)\footnote{K. A. Wieland \textit{et al}., Appl. Phys. Lett. {\bf88}, 52105 (2006).} is the third reported effect following extraordinary magnetoresistance (EMR) and extraordinary piezoconductance (EPC) that is based on the geometric enhancement of the conductivity of a metal semiconductor hybrid structure (MSH). Using a Van der Pauw plate setup, the voltage of the bare sample is compared directly to that of the MSH to determine the EOC, defined as $\{V_{MSH}-V_{bare}\}/V_{bare}$. In GaAs-In at 30K EOC $\approx$500\% has been observed. Bulk InSb-In structures have a room temperature EOC $\approx$50\%. Prior research\footnote{K. A. Wieland \textit{et al}., Phys. Rev. B., \textbf{73} 155305 (2006).} has shown that the one may increase the EOC by using a semiconductor with a large differential e-h mobility. Te doped $n$-type InSb thin films (n$= 2.11\times10^{22}$ m$^{-3}$ and $\mu_{e} =4.02$ m$^2/$Vs) are therefore prime candidates for room temperature EOC. Thin film Au shunts were chosen because of their coefficient of thermal expansion and non-magnetic properties. These MSHs were illuminated with Ar focused 488.0nm light and studied as a function of the position of the laser spot and temperature.\\