Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlOx for Crystalline Si Passivation

Zhen Zheng; Junyang An; Ruiling Gong; Yuheng Zeng; Jichun Ye; Linwei Yu; Ileana Florea; Pere Roca I Cabarrocas; Wanghua Chen

doi:10.3390/nano11071803

Coupled Investigation of Contact Potential and Microstructure Evolution of Ultra-Thin AlO_x for Crystalline Si Passivation

Nanomaterials (Basel). 2021 Jul 12;11(7):1803. doi: 10.3390/nano11071803.

Authors

Zhen Zheng¹, Junyang An¹, Ruiling Gong¹, Yuheng Zeng², Jichun Ye², Linwei Yu³, Ileana Florea⁴, Pere Roca I Cabarrocas⁴, Wanghua Chen¹

Affiliations

¹ School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
² Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
³ National Laboratory of Solid State Microstructures, School of Electronics Science and Engineering/Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
⁴ Laboratory of Physics of Interfaces and Thin Films, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France.

Abstract

In this work, we report the same trends for the contact potential difference measured by Kelvin probe force microscopy and the effective carrier lifetime on crystalline silicon (c-Si) wafers passivated by AlO_x layers of different thicknesses and submitted to annealing under various conditions. The changes in contact potential difference values and in the effective carrier lifetimes of the wafers are discussed in view of structural changes of the c-Si/SiO₂/AlO_x interface thanks to high resolution transmission electron microscopy. Indeed, we observed the presence of a crystalline silicon oxide interfacial layer in as-deposited (200 °C) AlO_x, and a phase transformation from crystalline to amorphous silicon oxide when they were annealed in vacuum at 300 °C.

Keywords: AlOx; Kelvin probe force microscopy; SiOx; c-Si passivation; surface potential.