The Mechanism Behind the Annealing‐Induced Reduction of Infrared Absorption in Zinc‐Hyperdoped Silicon

Pulsed laser hyperdoping is widely investigated as an effective method for expanding the infrared absorption of silicon. Prior to further device fabrication, thermal treatment is commonly applied to hyperdoped silicon to repair lattice defects and activate dopants. However, it is observed that thermal treatment adversely affects the infrared absorption of hyperdoped silicon, and the underlying mechanisms remain incompletely understood. Herein, zinc‐hyperdoped silicon (Si:Zn) is prepared using vacuum magnetron sputtering combined with femtosecond laser pulses, and the mechanisms of the reduction in infrared absorption during conventional annealing of Si:Zn samples are investigated. The diffusion of zinc and its precipitation as zinc clusters in silicon are observed during the annealing process, leading to a decrease in the concentration of zinc dopants within the silicon lattice and consequent attenuation of infrared absorption. Building upon this understanding, the approach of short timescale annealing subjected to infrared rapid thermal annealing furnace is proposed to be employed as a method to mitigate the adverse effects of zinc transitional precipitation, resulting in enhancement of the performance of Si:Zn optoelectronic devices.