| Penulis/Author |
RUTH MEISYE KALOARI (1); ERI WIDIANTO (2); AGUS PUTRA DANA (3); ARIF LUKMANTORO (4); Prof. Dr.Eng. Edi Suharyadi, S.Si., M.Eng. (5); Takeshi Kato (6); Satoshi Iwata (7); Moh. Adhib Ulil Absor, S.Si., M.Sc., Ph.D. (8); Dr. Iman Santoso, S.Si., M.Sc. (9) |
| Abstrak/Abstract |
We report the study of optical properties of Bismuth (Bi) thin films using spectroscopic ellipsometry (SE) in the visible - ultraviolet (UV) light range (11000 cm-1 – 50000 cm-1). The Bi films have been grown using rf-sputtering with different thicknesses, namely, 5 nm, 15 nm, 20 nm, 25 nm, and 30 nm. The Bi films have been fabricated on top of Alumina with a large energy gap to avoid band hybridization, charge transfer, and interaction between Bi thin film and substrates. The results show that the optical properties of Bi films depend on the thickness of Bi films. A broad absorption hump and two broad absorption peaks, as represented by the imaginary part of the dielectric constant and real part of optical conductivity, occur at 17000 cm-1 and 32000 cm-1; 47000 cm-1, respectively. The absorption features might be related to electrons transition that involving p_x, p_y orbitals to p_z orbital throughout the high symmetry line of Bi first Brillouin zone. The absorption peaks decreased as the thickness reduced from 30 nm to 15 nm. However, a significant increase in those absorption peaks occurs at a 5 nm thickness. This anomalous is possibly due to the transition from three-dimension to two-dimension by quantum confinement effect, leading to the increase of Density of State (DOS) as the Bi goes to ultra thin-film thickness. |
