Contactless Determination of Electric Field in Metal–Insulator–Semiconductor Interfaces by Using Constant DC-Reflectivity Photoreflectance

Eiichi Kobayashi,Ryoga Inoue,Koya Satta,Takayuki Makino,Ken Suzuki

doi:10.3390/solids2020008

Eiichi Kobayashi, Ryoga Inoue + Show 3 more

Open Access

https://doi.org/10.3390/solids2020008

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Abstract

We applied photoreflectance (PR) spectroscopy for contactless determination of the electric field strength at buried interfaces in metal–insulator–semiconductor (MIS) structures. The PR is an all-optical version of an electromodulated reflectance spectroscopy. The tradeoff of this adoption is that this requires an additional feedback system to eliminate background problems induced by scattered pump light and/or photoluminescence. A microcomputer-based feedback system has been developed for this elimination. Despite the very tiny signal intensity, we successfully attained a sufficiently good signal–noise ratio to determine the electric field strength in oxide-based MIS interfaces that exhibits a large, unwanted photoluminescence signal. The field strength was evaluated to be ca. 0.25 kV/cm.

Highlights

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Modulation spectroscopy has played an important role in characterizing the optical properties of solids [1,2,3,4]
Due to its inherent derivative nature, the resultant spectrum becomes free from the broad background [5]. This spectroscopy has been mainly used for an electronic-band-structure characterization

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. To suppress the spurious contribution and to enhance the detection limit, Shen and coworkers [16] proposed keeping the direct current (DC) component (Vdc ) constant independent of the photon energy, enabling the facile a posteriori subtraction of the spurious signal contributions [17]. While this was originally termed a new normalization procedure, we rather call it a constant DC-reflectivity PR, in analogy with the constant photocurrent method [21].

Experimental Procedures

Experimental Results and Discussion

Conclusions