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Electrical and photoelectric measurements laboratory

The laboratory performs measurements of the C(VG), I(VG) and G(VG) characteristics of semiconductor structures with ultimate sensitivity and resolution of 0.1 fA / 0.5 μV. This is primarily done using the Agilent B1500A semiconductor device analyzer and Cascade Summit 12k semi-automatic probe station. Based on these characteristics, measured at different temperatures T and signal frequency f, following parameters are evaluated: semiconductor substrate doping level or profile, flat-band voltage VFB and threshold voltage VT, energy distributions of the density of interface traps Dit and border traps Nb, and distributions of other trap parameters (time constant τ and capture cross-section σ).

Admittance spectroscopy investigations can also be performed using Agilent 4294A precision impedance meter and specialized computer fitting software. This method allows to determine equivalent circuits of nanostructures and to evaluate charge carrier trap distributions in materials and interfaces. Also, the MPAS (multiparameter admittance spectroscopy) technique of visualization of measurement results is provided. The MPAS method consists in graphical analysis of a measured MOS capacitor conductance dispersion (Gm/ω) as a function of surface potential Φ_S (resulting from gate bias voltage VG) and of the inverse of the measuring signal angular frequency ω-1. With the MPAS method it is possible to evaluate the trap capture cross-section σn directly from the conductance dispersion map. All the above mentioned measurements can be made at different temperatures in the range of T = -60 - 200^oC.