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arXiv · 2102.11451

Huge permittivity and premature metallicity in Bi$_2$O$_2$Se single crystals

Zhuokai Xu·Jialu Wang·Tao Wang·Wanghua Hu·Xiaohui Yang·Xiao Lin
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Abstract

Bi$_2$O$_2$Se is a promising material for next-generation semiconducting electronics. It exhibits premature metallicity on the introduction of a tiny amount of electrons, the physics behind which remains elusive. Here we report on transport and dielectric measurements in Bi$_2$O$_2$Se single crystals at various carrier densities. The temperature-dependent resistivity ($\rho$) indicates a smooth evolution from the semiconducting to the metallic state. The critical concentration for the metal-insulator transition (MIT) to occur is extraordinarily low ($n_\textrm{c}\sim10^{16}$ cm$^{-3}$). The relative permittivity of the insulating sample is huge ($\epsilon_\textrm{r}\approx155(10)$) and varies slowly with temperature. Combined with the light effective mass, a long effective Bohr radius ($a_\textrm{B}^*\approx36(2)$ $\textrm{nm}$) is derived, which provides a reasonable interpretation of the metallic prematurity according to Mott's criterion for MITs. The high electron mobility ($\mu$) at low temperatures may result from the screening of ionized scattering centers due to the huge $\epsilon_\textrm{r}$. Our findings shed light on the electron dynamics in two dimensional (2D) Bi$_2$O$_2$Se devices.

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Zhuokai Xu, Jialu Wang, Tao Wang, Wanghua Hu, Xiaohui Yang, Xiao Lin. 2021-02-23. Huge permittivity and premature metallicity in Bi$_2$O$_2$Se single crystals. https://doi.org/10.1007/s11433-021-1683-5

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