Photoluminescence Spectroscopy of Low Dimensional Semiconductors

Kareem, Ajmal (2016) Photoluminescence Spectroscopy of Low Dimensional Semiconductors. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Ajmal Kareem (11MS091)) Ajmal_11MS091_Thesis.pdf - Submitted Version Restricted to Repository staff only Download (7MB)

Abstract

The field semiconductor optics, especially the emergence of 2D semiconductors with a wide variety of advantages like changes in properties while going from bulk to a few layers made me curious. A semiconductor is a substance, usually a solid chemical element or compound which has an electrical conductivity value falling between that of a conductor and insulator. The relevance of class of TMDC materials peaked higher because of advances in nanoscale material characterization and fabrication, owning to their promising optical and electronic properties. Photoluminescence is simply the spontaneous emission of light from a material under optical excitation. PL-spectroscopy is a contact-less nondestructive spectroscopic method commonly used to probe the intrinsic and extrinsic properties of both bulk semiconductor and nanostructure materials, making it suitable for my studies. In this project, I wanted to observe the behaviour and trends of a quantum well semiconductor sample, particularly GaAs MQW in different temperature conditions of sample and when excited with different powers of excitation radiation. The required creating the experimental setup required for doing basic PL measurement. After that I started taking readings for PL of GaAs MQW at 180 K and going down till 4K step wise, simultaneously collecting the data for different power of exciting radiation at each temperatures too. From observing the optical properties of the sample and the results obtained, I would like to conclude that photoluminescence is one of the finest spectroscopic methods to study the optical and electronic properties of semiconductors. Working on my project further, I want to work on PL of mono-layer samples belonging to TMDC (such as MoS₂, WS₂) and PL spectroscopy in pulse magnetic fields too. I hope the class of 2D semiconductors will have huge growth and promising researches in near future which will have numerous applications in electronic devices and related technologies.

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