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Mapping Doping Concentration in Si

neaSCOPE THz nanoimaging and spectroscopy is an excellent ready-to-use solution for quantitative carrier density profiling at 20 nm
scale , which does not require complicated calibration procedures and can be applied to any doped semiconducting material .
THz amplitude
AFM height
Carrier Density Quantification
n≈10 20 cm 3 ≈10 19
≈10 18
THz amplitude calculation for doped Si
≤10 17
1 µ m
Reflectance image at 1 THz acquired by neaSCOPE on the IMEC calibration sample exhibits contrast that depends on the free carrier density . Comparison of this contrast with the calculated reflectance at the imaging wavelength ( red dashed line in the bottom plot ) for p-doped Si of different doping levels allows for calibration-free extraction of the carrier concentration with nanoscale spatial resolution .
Normalized amplitude
10 16
10 17 10 18
10 19
n = 10 20 cm -3
1 5 10 Frequency [ THz ]
THz nanoscopy accurately determines the doping concentration of semiconductor materials .
A . J . Huber et al ., Nano Lett . 2008 , 8 , 3766 .
H . -G . von Ribbeck et al ., Opt . Express 2008 , 16 , 3430 . www . attocube . com