“Quantum Mechanics in Our Lab.” Optoelectronics and Semiconductors Laboratory 김중철, 조소연, 한송희

Introduction to Laboratory Raman spectroscopy 3. Photoluminescence Table of contents Introduction to Laboratory Raman spectroscopy 3. Photoluminescence

1. Introduction to Laboratory

Introduction to Laboratory Graphene Solar Cell 2-dimensional (2D) honeycomb lattice consisting of carbon atoms Semiconductors which convert Sun light into electricity Raman spectroscopy, Photoluminescence

2. Raman spectroscopy

Raman spectroscopy 〮In the Raman effect a photon is scattered inelastically by a crystal, with creation or annihilation of a phonon. Rayleigh Anti-Stokes Stokes Virtual state u=0 1 2

Phonon 〮 Phonon → quantized elastic wave 〮simple model of phonon linear lattice of particles connected by springs.

Phonon

Phonon Optical The atoms vibrate against each other, but their center of mass is fixed. Acoustic The atoms move together. Raman probes k=0 because of the very small momentum of photon

Example of Raman spectrum -Raman spectrum of single crystal CZTSe

3. Photoluminescence

Photoluminescence (PL)

Photoluminescence (PL) 〮Solution of Hamiltonian DFT(Density Functional Theory) Tight binding First principle k·p perturbation theory

Tight binding model in 1D

Application of PL GaAs band structure Diatomic crystal (2 atoms per unit cell)

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