Photocurrent Spectroscopy Study of Graphene / Hexagonal Boron Nitride Moiré Superlattice In the Far-Infrared Regime
Name
yang-jxyang-sm-physics-2024-thesis.pdf
Description
Thesis PDF
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14.64 MB
Format
Adobe PDF
Checksum (MD5)
00ce6a37f5dcf0701b3a329b6b3b5557
Author(s)
Yang, Jixiang
Advisor(s)
Ju, Long
Date Issued
May 2024
Publisher
Massachusetts Institute of Technology
Abstract
Two-dimensional (2D) materials and their heterostructures, especially those with moiré superlattices, have been one of the most fascinating topics in physics in recent years. Many interesting physics, for example the correlated insulating state at half- or quarter- fillings of the moiré band, happened in the far-infrared energy range. However, there are very few optical spectroscopic studies of these 2D materials due to many intrinsic limitations. In this thesis, I will introduce a method named Fourier-transform infrared (FTIR) photocurrent spectroscopy. I will discuss the advantage of this method, and why it is suitable for far-infrared studies of 2D materials. Then I will apply it to the monolayer graphene / hexagonal boron nitride (hBN) moiré superlattices, where I accurately measure the gap ∆ opened at charge-neutral point (CNP) by the moiré superlattice. The relationship between the gap size and the moiré wavelength will also be discussed. Finally, I will discuss the possibility of applying this technique to other novel physics phenomena and other 2D systems.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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