Contact and contactless porous silicon parameter measurement techniques

Natalya V Latukhina,Ivan V Schemerov,I A Shishkin,Svetlana P Kobeleva,G A Rogozhina

doi:10.3897/j.moem.4.4.39503

Abstract

In this work we have used contact and contactless techniques to measure the electrical resistivity of single crystal silicon wafers with porous layers of variable thickness synthesized on the surface. The porous layers have been synthesized on the surfaces of single crystal wafers with well pronounced microroughness pattern, either textured or grinded. We have used the classic four-probe method with a linear probe arrangement as the contact measurement technique, and the resonance microwave method based on microwave absorption by free carriers as the contactless measurement technique. Electrical resistivity distribution over the specimen surface has been mapped based on the measurement results. We have demonstrated a general agreement between the electrical resistivity distribution patterns as measured using the contact and contactless measurement techniques. To analyze the electrical resistivity scatter over the specimen surface area we have simulated the field distribution in the electrolyte during porous layer formation in a non-planar anode cell. The regularities of the electrical resistivity spatial distribution in different types of specimens are accounted for by specific porosity formation mechanisms which in turn are controlled by the initial microroughness pattern and the field distribution pattern in the electrolyte for each specific case.

Highlights

Contactless parameter measurement techniques are of special interest for nanomaterials which include porous silicon because contact measurement of their parameters may cause irreversible damage to their nanostructure
The electrical resistivity distribution pattern over the porous layer surface is directly related to the electric field propagation in the electrolyte and at the silicon/electrolyte boundary
After porous layer formation for 5 min the average electrical resistivity increases to 3.20 ± 0.11 Ohm×cm, the difference between the highest and the lowest electrical resistivity decreases to 22% for the maximum value and the area of homogeneous regions increases considerably (Fig. 1b)

Summary

Introduction

Contactless parameter measurement techniques are of special interest for nanomaterials which include porous silicon because contact measurement of their parameters may cause irreversible damage to their nanostructure. Electrical resistivity of porous silicon may very over an extremely wide range [1–3]. It depends on the porous layer technology used and on the initial material properties. Porosity formation in silicon structures during chemical and electrochemical etching has been simulated using a large number of models providing, to different extents, sufficient explanation of the physical regularities of this phenomenon [1–6]. There are several physical models [4–9] interpreting some porosity formation aspects from the standpoints of instability of the planar silicon/

Objectives

Results

Conclusion