Optical Conductivity Calculation of a Luttinger-Kohn Model Semiconductor GaAs Incorporating Electron-Hole Interactions Through a Vertex Function within Ladder Approximation

1.Abstract

The role of excitons in semiconducting material carries potential applications. Exciton signals usually do not appear much in optical absorption of semiconductor systems with a narrow gap, such as Gallium Arsenide. The optical conductivity of Gallium Arsenide has been recently calculated by the Density Functional Theory (DFT), in which the strong interaction between electron-hole is not taken into account. Based on these reasons we developed the method of calculation for the optical conductivity that includes the electron-hole interaction by using the k.p 8 band model through a vertex function within ladder approximation approach. The K.p model was chosen because it provides a description of 8 energy band (2 conduction band and 6 valence band) in which the role of spin-orbit coupling is also taken into account.

2.Keywords
excitons, GaAs, optical conductivity, vertex function, ladder approximation, k.p theory
3.Objective

1. Mendapatkan hasil perhitungan konduktifitas optis sistem GaAs dimana diharapkan kemunculan sinyal eksiton pada kurva.
2. Mengembangkan algoritma perhitungan berbasis pendekatan k.p 8 band yang memperhitungkan koreksi vertex

4.Methodology

Penelitian dilakukan dengan memodelkan struktur kristal Gallium Arsenite dengan satu unit sel berbentuk zincblende. Lalu secara komputasi menghitung konduktifitas optis Gallium Arsenite menggunakan kubo formula dengan dan tanpa interaksi elektron hole. Bagian �non-interacting� Hamiltonian sistem Galium Arsenite ini akan menggunakan model hamiltonian k.p yang melibatkan 8 pita energi di sekitar band gap. Interaksi lalu ditambahkan dengan cara menyelesaikan Bethe-Salpeter Equation (BSE) melalui fungsi vertex dengan pendekatan ladder diagram.
Metode komputasi yang akan digunakan menggunakan komputer dengan operating system linux. Code program dikembangkan dengan bahasa Fortran90. Untuk mengkalkulasi matrix berdimensi besar digunakan LAPACK (Linear Algebra Packange), serta MPI (Message Passing Interface) untuk komputasi paralel yang melibatkan banyak prosesor sekaligus.

5.Team

Muhammad Aziz Madjidi, Ph.D
Humaira Khairunnisa

6.Computation plan (required processor core hours, data storage, software, etc)

32 core, 1 Gb
lapack, mpi

7.Source of funding
Universitas Indonesia
8.Target/outputs
Conference proceedings (ISCPMS 2017 dan/atau ISCPFM 2017).
9.Date of usage
21/04/2017 - 30/06/2017
10.Gpu usage
-
11.Supporting files
prop_1492750875.pdf
12.Created at
21/04/2017
13.Approval status
approved