Titanium hyperdoped black silicon prepared by femtosecond laser irradiation: first-principle calculations and experimental verification
Song Huang, Anhua Wu, Guanting Song, Jiaxin Cao, Jianghong Yao, Qiang Wu, Weiqing Gao, Jingjun Xu
Abstract
Black silicon materials prepared via microstructuring and hyperdoping by ultrafast laser irradiation have attracted immense attention owing to their high absorption and photon sensitivity across a broadband spectral range.However, a conflict exists between the repair requirements for the high amount of laser-induced damage and the thermally unstable hyperdoped impurities, resulting in low photon sensitivity and rapid decay at subbandgap wavelengths for the annealed black silicon.In this work, the properties of titanium (Ti) hyperdoped silicon have been explored using first-principle calculations.The findings of the study reveal that the interstitial Ti atoms exhibit a deep impurity band and low formation energy in silicon, which may be responsible for the stable subbandgap absorption that is achieved.Furthermore, femtosecond laser irradiation and rapid thermal annealing have been applied to manufacture Ti-hyperdoped black silicon (b-Si:Ti).The b-Si:Ti compound prepared by hyperdoping displayed high absorption across the visible and infrared ranges, with absorptance exceeding 90% for visible lights and 60% for subbandgap wavelengths.Additionally, the subbandgap absorption remains high even after intense thermal annealing, indicating a stable deep-level impurity of Ti in silicon.The experimental findings are consistent with the simulation results and complement each other to reveal the physical mechanisms responsible for the high performance of b-Si:Ti.The results thus demonstrate promising prospects for the application of black silicon in high-efficiency solar cells, photoelectric imaging, and flip-chip interconnection systems.