EFEK STRAIN TERHADAP SIFAT ELEKTRONIK SILICENE : KAJIAN KOMPUTASI BERBASIS DFT (DENSITY FUNCTIONAL THEORY)

KHAERUL UMAM, Drs. Pekik Nurwantoro, M.S., Ph.D; Sholihun, S.Si., M.Sc., Ph.D

2017 | Skripsi | S1 FISIKA

Telah dilakukan kajian komputasi berbasis density functional theory (DFT) pada material 2D silikon yaitu silicene. Setelah dibuktikan adanya perilaku 'massless Dirac fermion' dan struktur geometri buckle pada keadaan optimal, pemberian strain dua-sumbu secara compressive atau tensile telah merubah struktur elektronik dan buckle silicene. Perubahan nilai buckle semakin besar atau kecil tergantung apakah dikenai compressive atau tensile strain. Perubahan struktur elektronik terjadi pada strain ±8% karena kenaikan energi valence band dan penurunan energi conduction band sehingga pada strain ±8% pita energi pada simetri-Gamma dan simetri-K saling overlap yang mengakibatkan silicene menjadi konduktor, overlap energi semakin besar hingga strain -10% dan +12% yaitu 0,7650 eV dan 1,0326 eV. Strain -10% mengakibatkan konstanta buckling semakin besar menjadi 0,8467 Angstrom sementara strain +12% mengakibatkan konstanta buckling semakin kecil menjadi 0,1994 Angstrom.

Computational study based on density functional theory (DFT) has been investigated for 2D silicon atoms : silicene. After massless Dirac fermion characteristic and buckle geometry structure on optimal parameter have been proved, applied biaxial strain as compressive and tensile has changed electronic properties and geometry structure silicene. The changed values of buckling will increase or decrease whether those are applied as the compressive or tensile strain. The changed electronic structure is applied strain ±8% because shifted valence band and conduction band into Fermi level, as the result energy band on Gamma-point and K-point overlap and finally silicene as a conductor, overlap energy will increase until applied strain -10% and +12% about 0.7650 eV and 1.0326 eV respectively. Strain -10% yield buckling constant will increase to 0.8467 Angstrom while strain +12% yield buckling constant will decrease to 0.1994 Angstrom.

Kata Kunci : Silicene, DFT, Dirac fermion, strain.