Sheet conductance of laser-doped layers using a Gaussian laser beam: an effective depth approximation
Year: 2024
Type: article
Abstract: Laser doping of silicon with pulsed and scanned laser beams is now well-established to obtain defect-free, doping profile tailored, and locally selectively doped regions with a high spatial resolution. Picking the correct laser parameters (pulse power, pulse shape, and scanning speed) impacts the depth and uniformity of the melted region geometry. This work performs laser doping on the surface of single crystalline silicon, using a pulsed and scanned laser profile with a Gaussian intensity distribution. A deposited boron oxide precursor layer serves as a doping source. Increasing the local inter-pulse distance $$x_\text {irr}$$ x irr between subsequent pulses causes a quadratic decrease of the sheet conductance $$G_\text {sh}$$ G sh of the doped surface layer. Here, we present a simple geometric model that explains all experimental findings. The quadratic dependence stems from the approximately parabolic shape of the individual melted regions directly after the laser beam has hit the Si surface. The sheet resistance depends critically on the intersection depth $$d_\text {ch}$$ d ch and the distance $$x_\text {irr}$$ x irr of overlap between two subsequent, neighboring pulses. The intersection depth $$d_\text {ch}$$ d ch quadratically depends on the pulse distance $$x_\text {irr}$$ x irr and therefore also on the scanning speed $$v_\text {scan}$$ v scan of the laser. Finally, we present a simple model that reduces the complicated three dimensional, laterally inhomogeneous doping profile to an effective two-dimensional, homogeneously doped layer which varies its thickness with the scanning speed.
Source: Applied Physics A
Authors: Mohamed Hassan, Juergen H. Werner
Institution: University of Stuttgart
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,590
OpenAlex ID: W4402639399