Phosphorus out-diffusion in laser molten silicon

Journal Article · Tue Apr 14 04:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4917048· OSTI ID:22402853

Köhler, J. R.; Eisele, S. J. ^[1]

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1. Institut für Photovoltaik (ipv), Universität Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart (Germany)

Laser doping via liquid phase diffusion enables the formation of defect free pn junctions and a tailoring of diffusion profiles by varying the laser pulse energy density and the overlap of laser pulses. We irradiate phosphorus diffused 100 oriented p-type float zone silicon wafers with a 5 μm wide line focused 6.5 ns pulsed frequency doubled Nd:YVO{sub 4} laser beam, using a pulse to pulse overlap of 40%. By varying the number of laser scans N{sub s} = 1, 2, 5, 10, 20, 40 at constant pulse energy density H = 1.3 J/cm{sup 2} and H = 0.79 J/cm{sup 2} we examine the out-diffusion of phosphorus atoms performing secondary ion mass spectroscopy concentration measurements. Phosphorus doping profiles are calculated by using a numerical simulation tool. The tool models laser induced melting and re-solidification of silicon as well as the out-diffusion of phosphorus atoms in liquid silicon during laser irradiation. We investigate the observed out-diffusion process by comparing simulations with experimental concentration measurements. The result is a pulse energy density independent phosphorus out-diffusion velocity v{sub out} = 9 ± 1 cm/s in liquid silicon, a partition coefficient of phosphorus 1 < k{sub p} < 1.1 and a diffusion coefficient D = 1.4(±0.2)cm{sup 2}/s × 10{sup −3 }× exp[−183 meV/(k{sub B}T)].

• OSTI ID: 22402853
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 14 Vol. 117; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
COMPUTERIZED SIMULATION
CONCENTRATION RATIO
DIFFUSION
ELECTROMAGNETIC PULSES
ENERGY DENSITY
ION MICROPROBE ANALYSIS
IRRADIATION
LASER RADIATION
MASS SPECTROSCOPY
MELTING
P-N JUNCTIONS
PHOSPHORUS
SILICON
SOLIDIFICATION