Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy

TL;DR

This paper demonstrates that flash-lamp annealing effectively hyperdopes silicon with selenium, achieving high substitutional incorporation, improved electrical properties, and better scalability compared to laser annealing methods.

Contribution

It introduces a solid phase flash-lamp annealing technique for selenium hyperdoping in silicon, reducing surface segregation and enhancing scalability over laser-based methods.

Findings

Flash-lamp annealing achieves ~70% substitutional selenium in silicon.

Resistivity and mobility are improved compared to laser annealed samples.

Method prevents surface segregation and is scalable.

Abstract

Chalcogen-hyperdoped silicon shows potential applications in silicon-based infrared photodetectors and intermediate band solar cells. Due to the low solid solubility limits of chalcogen elements in silicon, these materials were previously realized by femtosecond or nanosecond laser annealing of implanted silicon or bare silicon in certain background gases. The high energy density deposited on the silicon surface leads to a liquid phase and the fast recrystallization velocity allows trapping of chalcogen into the silicon matrix. However, this method encounters the problem of surface segregation. In this paper, we propose a solid phase processing by flash-lamp annealing in the millisecond range, which is in between the conventional rapid thermal annealing and pulsed laser annealing. Flash lamp annealed selenium-implanted silicon shows a substitutional fraction of around 70% with an implanted concentration up to 2.3%. The resistivity is lower and the carrier mobility is higher than those of nanosecond pulsed laser annealed samples. Our results show that flash-lamp annealing is superior to laser annealing in preventing surface segregation and in allowing scalability.