Time-resolved Ellipsometry to Study Extreme Non-equilibrium Electron Dynamics in Nanostructured Semiconductors

2012 ◽  
Vol 1426 ◽  
pp. 395-400
Author(s):  
T. W. Roger ◽  
A. Kaplan
Keyword(s):  
Silicon Nanocrystals ◽  
Crystalline Silicon ◽  
Free Carrier ◽  
Free Carrier Absorption ◽  
Electron Dynamics ◽  
Silicon Phase ◽  
Time Resolved ◽  
Pump Probe ◽  
Carrier Absorption ◽  
Nanostructured Semiconductors

ABSTRACTWe present a femtosecond pump-probe ellipsometer operating over a spectral range of 1.4 – 1.7 eV with a ∼50fs time resolution. The calibration and preliminary findings of the setup are discussed. We tested the apparatus on bulk crystalline silicon (not shown here) and on silicon nanocrystals embedded in an amorphous silicon phase. The ellipsometric angles (ψ, Δ) were determined as a function of time and wavelength. The results suggest that a simple Drude model of free carrier absorption is not sufficient to explain the findings.

Time-resolved measurement of free carrier absorption, diffusivity, and internal quantum efficiency in silicon

2013 ◽  
Vol 103 (9) ◽  
pp. 092101 ◽  
Author(s):  
Jet Meitzner ◽  
Frederick G. Moore ◽  
Brock M. Tillotson ◽  
Stephen D. Kevan ◽  
Geraldine L. Richmond
Keyword(s):  
Quantum Efficiency ◽  
Internal Quantum Efficiency ◽  
Free Carrier ◽  
Free Carrier Absorption ◽  
Time Resolved ◽  
Carrier Absorption

Influence of Doping on the Structural Properties of Micro-Crystalline Silicon Prepared with the VHF-GD Technique at Low Deposition Temperatures.

1991 ◽  
Vol 219 ◽  
Author(s):  
F. Fingera ◽  
K. Prasad ◽  
S. Dubail ◽  
A. Shah ◽  
X.-M. Tang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Crystalline Silicon ◽  
Free Carrier ◽  
Free Carrier Absorption ◽  
Very High Frequency ◽  
Absorption Bands ◽  
Undoped Material ◽  
Air Interface ◽  
Carrier Absorption ◽  
Infrared Absorption Bands

ABSTRACTIn doped and undoped microcrystalline silicon prepared with Very High Frequency Glow Discharge, hydrogen is found to be mainly located at the grain boundaries from where it desorbs easily at low annealing temperatures. In undoped material hydrogen evolution peaks are between 400°C and 500°C. Upon doping, a new major peak appears at 300°C and a strong reduction of the typical Si-H infrared absorption bands are found for doped samples when annealed up to 300°C. This is accompanied by an increase of the conductivity due to either de-passivation of dopants in the crystallites or a favourable reconstruction at the grain boundaries. Hydrogen profiles show a hydrogen depletion at the film/air interface that is more profound in doped material, thus correlating with the appearance of the low temperature evolution peak. The high free carrier density in the crystallites of the doped material gives rise to strong optical absorption. Although correlating nicely with conductivity, the free carrier absorption cannot be evaluated simply in terms of die Drude theory. In view of the high conductivities and the dominance of Si-H surface bonds we argue that our material does not contain a large amount of amorphous tissue.

Near-infrared free-carrier absorption in silicon nanocrystals

2009 ◽  
Vol 34 (21) ◽  
pp. 3397 ◽  
Author(s):  
Rohan D. Kekatpure ◽  
Mark L. Brongersma
Keyword(s):  
Silicon Nanocrystals ◽  
Near Infrared ◽  
Free Carrier ◽  
Free Carrier Absorption ◽  
Carrier Absorption

Optically Detected Temperature Dependences of Carrier Lifetime and Diffusion Coefficient in 4H- and 3C-SiC

2011 ◽  
Vol 679-680 ◽  
pp. 205-208 ◽  
Author(s):  
Jawad ul Hassan ◽  
Patrik Ščajev ◽  
Kęstutis Jarašiūnas ◽  
Peder Bergman
Keyword(s):  
Diffusion Coefficient ◽  
Decay Time ◽  
Carrier Lifetime ◽  
Free Carrier ◽  
Free Carrier Absorption ◽  
Time Resolved ◽  
Temperature Dependences ◽  
Carrier Absorption ◽  
Time Resolved Photoluminescence ◽  
And Diffusion

Free carrier dynamics has been studied in 4H- and 3C-SiC in a wide temperature range using time-resolved photoluminescence, free carrier absorption, and light induced transient grating techniques. Considerably high carrier lifetime was observed in 3C-SiC epitaxial layers grown on 4H-SiC substrates using hot-wall CVD with respect to previously reported values for 3C-SiC grown either on Si or on 6H-SiC substrates. The temperature dependences of carrier lifetime and diffusion coefficient for 4H- and 3C-SiC were compared. Shorter photoluminescence decay time with respect to free carrier absorption decay time was observed in the same 4H-SiC sample, while these techniques revealed similar trends in the carrier lifetime temperature dependencies. However, the latter dependences for hot-wall CVD-grown 3C layers were found different if measured by time resolved photoluminescence and free carrier absorption techniques.

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