Critical behavior of the insulator-to-metal transition in Te-hyperdoped Si

Hyperdoping Si with chalcogens is a topic of great interest due to the strong sub-band-gap absorption exhibitedby the resulting material, which can be exploited to develop broadband room-temperature infrared photodetectorsusing fully Si-compatible technology. Here, we report on the critical behavior of the impurity-driven insulator-tometaltransition in Te-hyperdoped Si layers fabricated via ion implantation followed by nanosecond pulsed-lasermelting. Electrical transport measurements reveal an insulator-to-metal transition, which is also confirmed andunderstood by density functional theory calculations. We demonstrate that the metallic phase is governed by apower-law dependence of the conductivity at temperatures below 25 K, whereas the conductivity in the insulatingphase is well described by a variable-range hopping mechanism with a Coulomb gap at temperatures in the rangeof 2-50 K. These results show that the electron wave function in the vicinity of the transition is strongly affectedby the disorder and the electron-electron interaction.