Title :
Infrared absorption and momentum relaxation of free carriers in silicon generated by subpicosecond above band gap radiation
Author :
Meyer, Jochen ; Elezzabi, Abdulhakem Y. ; Hughes, Michael K Y
Author_Institution :
Dept. of Phys., British Columbia Univ., Vancouver, BC, Canada
fDate :
4/1/1995 12:00:00 AM
Abstract :
The absorption of infrared radiation in Si of various dopings is investigated after free carriers have been generated by absorption of a subpicosecond laser pulse of above band gap photon energy. A theoretical model is presented which predicts the transmission coefficient for an infrared light pulse through a photogenerated e-h plasma in Si of various surface free carrier densities. Experiments are performed in which the transmission coefficient is measured for a 10.6 μm, ~20 ps laser pulse through a crystalline Si-wafer after it has been irradiated by a 490 fs, 616 nm laser pulse of intensities varying over several orders of magnitude. By fitting the experimental data to the theoretical predictions the imaginary component of the dielectric constant is accurately determined. From the results the free carrier absorption cross sections and the average momentum relaxation times are calculated. The momentum relaxation times in n-doped Si at 10.6 fs are much shorter than that of 26.5 fs observed in intrinsic and p-doped Si
Keywords :
carrier density; carrier mobility; elemental semiconductors; high-speed optical techniques; laser beams; light absorption; permittivity; silicon; 10.6 mum; 20 ps; 265 fs; 490 fs; 616 nm; Si; above band gap photon energy; average momentum relaxation times; crystalline Si-wafer; dielectric constant; free carrier absorption cross section; free carrier densities; free carrier generation; free carriers; infrared absorption; infrared radiation; laser pulse; momentum relaxation; momentum relaxation times; n-doped Si; p-doped Si; photogenerated e-h plasma; silicon; subpicosecond above band gap radiation; subpicosecond laser pulse absorption; transmission coefficient; Doping; Electromagnetic wave absorption; Laser modes; Laser theory; Optical pulse generation; Optical pulses; Photonic band gap; Plasma measurements; Pulse measurements; Semiconductor process modeling;
Journal_Title :
Quantum Electronics, IEEE Journal of
