Two-dimensional dopant profiling by scanning capacitance force microscopy

We developed scanning capacitance force microscopy (SCFM) capable of mapping local differential capacitance (∂C/∂V), based on atomic force microscopy (AFM), by detecting an electrostatic force (ESF) between a tip and a sample. While an electric field alternating at an angular frequency (ω) is applied between the tip and the sample, an induced ESF oscillating at its third harmonic frequency (3ω), which contain information on ∂C/∂V is detected using a lock-in amplifier (LIA). In this paper, we showed some dynamic-mode SCFM results obtained on a Si test sample. Clear dopant contrasts were obtained by dynamic-mode SCFM operated in air. An apparent position of the p–n junction was moved when an applied d.c. bias voltage was changed. A dynamic-mode SCFM image obtained in a vacuum condition utilizing frequency modulation (FM) detection method also showed clear dopant contrast.