Silicon Hyperdoped with Selenium by Ion Implantation Followed by Pulsed Laser Annealing

Selenium hyperdoped silicon is a promising material for intermediate-band solar cells and extended infrared photodiodes. Selenium-rich layers were fabricated by Se ion implantation followed by pulsed laser annealing (690 nm, 70 ns). Laser energy density W was set as 1.5, 2 and 2.5 J/cm
²
and number of impulses was set as 1 or 3 for each energy density. Rutherford backscattering with channeling, Raman scattering, scanning electron and optical microscopy as well as photoluminescence techniques were used for diagnostics of structural and optical properties of Se-rich silicon layers. It has been shown that laser irradiation leads to silicon recrystallization and significant impurity redistribution in the implanted layer. It has been observed the formation of the uniform plateau with a concentration of Se around (3 × 10
¹⁹
- 4 × 10
²⁰
)cm
^-3
up to a depth of 300-400 nm with an accumulation of impurity in a near-surface oxide layer 5-10 nm. According to the RBS/channeling data, the substitutional fraction of incorporated Se atoms in silicon lattice after laser treatment is 60-80%. Analysis of photoluminescence spectra has revealed that pulsed laser irradiation of the implanted layer with W = 1.5J/cm
²
leads to the formation of vacancy and interstitial clusters. As the energy in the pulse increases, the bands related with these types of defects disappear from the photoluminescence spectra.