Nanoscale Electronic Measurements of Semiconductors Using Kelvin Probe Force Microscopy

Abstract

As characteristic dimensions of semiconductor devices continue to shrink, the ability to characterize structure and electronic properties in such devices at the nanometer scale has come to be of outstanding importance.

The Kelvin probe force microscopy technique has already been demonstrated as a powerful tool for measuring electrostatic forces and electric potential distribution with nanometer resolution. In this review, we demonstrate several recent applications of this technique. We begin by reviewing the basics of the method and presenting the basic experimental setup. Section 2 presents measurements conducted on operating GaP light emitting diode. The operating device surface band structure was imaged with nanometer resolution, and it was shown that the surface band structure is governed by absorption of the internal light emission. We then demonstrate how the Kelvin probe force microscopy can be used for measuring minority-carrier diffusion length in semiconductors. It is shown that this method could be very useful in measuring very short diffusion lengths (< 1 µm). The last section focuses on the sensitivity and spatial resolution in semiconductor measurements. We present a framework that allows extracting the real surface potential taking into account the tip-sample electrostatic interaction. The model is compared to ultra high vacuum Kelvin probe force microscopy measurements of atomic steps on GaP.