Carrier accumulation and depletion in point-contact capacitance-voltage measurements

Yuichi Naitou

doi:10.1063/1.5005861

Abstract

Scanning capacitance microscopy (SCM) is a variation of atomic force microscopy in which a conductive probe tip detects the bias modulated capacitance for the purpose of measuring the nanoscale semiconductor carrier concentration. SCM can be regarded as a point-contact capacitance-voltage system, and its capacitance-voltage properties are different from those of a conventional parallel-plate capacitor. In this study, the charge accumulation and depletion behavior of a semiconductor sample were closely investigated by SCM. By analyzing the tip-sample approach curve, the effective probe tip area and charge depletion depth could be quantitatively determined.

Highlights

Scanning capacitance microscopy (SCM)[1] and its advanced variation, scanning nonlinear dielectric microscopy (SNDM),[2] are analogues of atomic force microscopy (AFM) in which a conductive probe tip detects a bias modulated capacitance for the purpose of measuring the nanoscale semiconductor carrier concentration
This is because the dC/dV signal originates from the modulation of the depletion layer by the applied bias voltage just beneath the SCM probe tip
This signal reflects the semiconductor carrier concentration; i.e., the ∆C/∆Z signal monotonously increases with increasing carrier concentration.[16,17]

Summary

Introduction

Scanning capacitance microscopy (SCM)[1] and its advanced variation, scanning nonlinear dielectric microscopy (SNDM),[2] are analogues of atomic force microscopy (AFM) in which a conductive probe tip detects a bias modulated capacitance for the purpose of measuring the nanoscale semiconductor carrier concentration. Carrier accumulation and depletion in point-contact capacitance-voltage measurements The carrier concentration is one of the most important parameters of semiconductors such as doped silicon (Si)[6,7,8,9] and germanium (Ge).[10] For conducting semiconductor carrier concentration analyses, contact-mode atomic force microscopy (C-AFM)-based SCM and SNDM detect a bias-modulated capacitance, i.e., the dC/dV signal.

Results

Conclusion