Structure and Broad Infrared Absorption of Silicon Hyperdoped with Ion‐Implanted Selenium

We report a comparative study of selenium‐hyperdoped silicon layers subjected to two‐step thermal annealing (TA) and pulsed‐laser annealing (PLA). Structural recovery and impurity redistribution were examined by Rutherford backscattering spectrometry in random and channeling modes and optical spectroscopy. Both annealing approaches restore crystallinity and high Se substitutional incorporation (53% and 72% for TA and PLA samples, respectively). However, TA leaves a higher fraction of interstitial selenium that serves as carrier‐trapping centers. Optical measurements reveal the formation of a Se‐related impurity band at 1–5 μm only in the PLA samples, whereas the TA samples exhibit merely a weak free‐carrier absorption. In contrast to TA samples, PLA samples demonstrate pronounced infrared (IR) photoresponse under reverse bias. These findings underline the decisive role of dopant configuration in the optoelectronic properties of hyperdoped silicon and suggest promising opportunities for silicon‐based IR photodetectors.