Final Report - Faculty of Physics

Final Report CEMOS G5MA-CT-2002-04062 Page 26/43
Kelvin Probe Microscopy principle & applications by R.Bożek
The Atomic Force Microscope previously existing at the Division has recently been
upgraded and now a Kelvin Probe Microscopy (KPM) can be performed (see Annex L4).
Such sub-micron photovoltage spectroscopy allows for semi-quantitative measurements
of spatial (lateral) resolution of 100 nm. Using the technique electric charges,
precipitations (composition, phase), roughness of buried interfaces other factors
influencing work function can be detected
„plan
view”
2 mm
layer
Fig.7. KPM (left panel) and AFM (right panel) images of the same area of GaN sample
The information, which can be obtained using the KPM is summarized in Fig.7. The
topography of a GaN sample obtained using the FPM (left-hand side) is compared to the
surface topography resulting from a usual AFM measurement. Both pictures present the same
part of the sample. It can be seen that more details of a structure buried below the surface are
visible on the FPM image. [27-29]
Luminescence from a modulation-doped GaAs/InGaAs/GaAlAs quantum well in
magnetic field by A. Babiński et al
Optical emission from a modulation-doped pseudomorphic GaAs/InGaAs/GaAlAs
quantum well (QW) has been investigated. Oscillations of the photoluminescence (PL)
intensity in magnetic field are investigated. Recombination processes giving rise to the PL
are identified and their effect on the PL is established. It has been shown that measurements
of the oscillations in the low-energy tail of the PL can provide information on the density of