Wet Chemical Oxidation to Improve Interfacial Properties of Al2O3/Si and Interface Analysis of Al2O3/SiOx/Si Structure Using Surface Carrier Lifetime Simulation and Capacitance–Voltage Measurement

Kwan Hong Min,Hae-Seok Lee,Jeong In Lee,Myeong Sang Jeong,Sungeun Park,Sungjin Choi,Donghwan Kim,Hee-Eun Song,Min Gu Kang,Yoonmook Kang

doi:10.3390/en13071803

Kwan Hong Min, Hae-Seok Lee + Show 8 more

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https://doi.org/10.3390/en13071803

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Journal: Energies	Publication Date: Apr 8, 2020
Citations: 2	License type: CC BY 4.0

Affiliation: Korea Institute of Energy Research, Korea University

Abstract

A thin silicon oxide (SiOx) layer (thickness: 1.5–2.0 nm) formed at an Al2O3/Si interface can enhance the interface properties. However, it is challenging to control the characteristics of thin SiOx layers because SiOx forms naturally during Al2O3 deposition on Si substrates. In this study, a ~1.5 nm-thick SiOx layer was inserted between Al2O3 and Si substrates by wet chemical oxidation to improve the passivation properties. The acidic solutions used for wet chemical oxidation were HCl:H2O2:H2O, H2SO4:H2O2:H2O, and HNO3. The thicknesses of SiOx layers formed in the acidic solutions were ~1.48, ~1.32, and ~1.50 nm for SiOx-HCl, SiOx-H2SO4, and SiOx-HNO3, respectively. The leakage current characteristics of SiOx-HNO3 were better than those of the oxide layers formed in the other acidic solutions. After depositing a ~10 nm-thick Al2O3 on an SiOx-acidic/Si structure, we measured the effective carrier lifetime using quasi steady-state photoconductance and examined the interfacial properties of Al2O3/SiOx-acidic/Si using surface carrier lifetime simulation and capacitance–voltage measurement. The effective carrier lifetime of Al2O3/SiOx-HNO3/Si was relatively high (~400 μs), resulting from the low surface defect density (2.35–2.88 × 1010 cm−2eV−1). The oxide layer inserted between Al2O3 and Si substrates by wet chemical oxidation helped improve the Al2O3/Si interface properties.

Highlights

silicon oxide (SiOx) are ~1.48 nm for SiOx-HCl, ~1.32 nm for SiOx-H2SO4, and ~1.50 nm for SiOx-HNO3
The negativeofQthe f values of the silicon oxides formed in the chemical oxidation on an Si substrate
× 10to surface in different acidic solutions was in the range of 1.32–1.5 nm, which was similar that of SiOx

Summary

Introduction

The surface passivation of crystalline silicon (c-Si) solar cells can be improved using various materials such as SiO2 [1,2,3,4,5,6], SiNx [7,8,9], Al2 O3 [10,11,12,13], TiOx [14,15,16], MoOx [17,18], and poly-Si [19,20,21,22]. We considered a method to improve the interfacial properties of an Al2 O3 /Si structure by inserting a thin silicon oxide layer between Al2 O3 and Si substrates. The quality of the silicon oxide formed is excellent, it is difficult to control the thickness (

Experimental

Results and Discussions

Conclusions