Two-Dimensional Carrier Profiling on Lightly Doped n-Type 4H-SiC Epitaxially Grown Layers

Abstract

Electronically active dopant profiles of epitaxially grownn-type 4H-SiC calibration layer structures with concentrations ranging from 3.1015cm-3to 1·1019cm-3have been investigated by non-contact Scanning Probe Microscopy (SPM) methods. We have shown that Kelvin Probe Force Microscopy (KPFM) and Electrostatic Force Microscopy (EFM) are capable of resolving two-dimensional carrier maps in the low doping concentration regime with nanoscale spatial resolution. Furthermore, different information depths of this wide band gap semiconductor material could be assessed due to the inherent properties of each profiling method. We additionally observed a resolution enhancement under laser illumination which we explain by reduced band-bending conditions. To gauge our SPM signals, we utilized epitaxially grown layers which were calibrated, in terms of dopant concentration, byC-Vmeasurements.

Dopant imaging of power semiconductor device cross sections

“…KPFM measures the contrast in the CPD signal by applying a bias voltage VCPD to compensate electrostatic forces, which is sensitive to defect structures at the surface. A decrease of the defect density by suitable sample preparation and the reduction of the surface band bending by illumination with sub-bandgap irradiation are feasible strategies to minimize band bending and to optimize the CPD contrast mechanism [9,10]. SCFM seems to be a valuable method to visualize differently doped regions, but still needs further sophisticated modelling to obtain quantitative results.…”

Junction Barrier Schottky (JBS) Rectifier Interface Engineering Facilitated by Two-Dimensional (2D) Dopant Imaging

“…Similar to KPFM, SCFM is offering a quantification potential as this technique inherently involves local capacitance spectroscopy measurements. However, further theoretical studies are necessary and until now a quantification is only possible by a comparison to precisely gauged calibration samples that were beforehand analyzed by C-V measurements [15].…”