Defect engineering of two-dimensional materials with focused ion beam techniques

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master_Edwards_Christopher_2026.pdf (51.48 MB)

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School of Electrical Engineering | Master's thesis
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Date

2025-12-31

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Major/Subject

Microelectronic Circuit Design

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Degree programme

Master's Programme in Electronics and Nanotechnology
Elektroniikan ja nanoteknologian maisteriohjelma
Magisterprogrammet i elektronik och nanoteknologi

Language

en

Pages

65

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Abstract

As the need for smaller and more efficient electronic devices grows, the scaling of silicon-based electronics to meet these requirements presents increasingly difficult challenges. Two-dimensional (2D) materials are a promising group of materials for miniature and efficient electrical devices due to their characteristic thinness, tuneability, and attractive electrical and optical properties. Indium selenide (InSe) and gallium selenide (GaSe) are two potential 2D material examples that have displayed promising photonic and optoelectronic applications due to their ease of modification via defect engineering. However, little research has been conducted on highly local defect engineering methods such as with a focused ion beam (FIB). This thesis demonstrates the process of engineering bulk InSe and GaSe samples with modified optical responses. By utilising a gallium FIB, a new vibrational peak was observed in InSe. Additional samples employed a 50 nm aluminium (Al) layer as a shield to protect the 2D materials from the destructive FIB process, preserving their crystallinity. After FIB modification, Al-covered GaSe samples produced a twofold enhancement in the intensity of the photoluminescence and displayed a gradual redshift in the peak energy of the photoluminescence. These tuneable 2D materials are potentially useful for novel electronic and optoelectronic applications such as in photodetectors, light-emitting devices, and light-activated chemical sensors.

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Supervisor

Sun, Zhipei

Thesis advisor

Liapis, Andreas

Keywords

2D materials, defect engineering, focused ion beam, post-transition metal monochalcogenides, raman spectroscopy, photoluminescence

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https://urn.fi/URN:NBN:fi:aalto-202601191533

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[dipl] Sähkötekniikan korkeakoulu / ELEC