U Hashim⁽¹⁾, K L Foo⁽²⁾,
(1) 
(2) 

Syamsu Rosid⁽¹⁾, Romadoni N⁽²⁾, Koesnodo Koesnodo⁽³⁾, Prabowo Nuridianto⁽⁴⁾,
(1) 
(2) 
(3) 
(4) 

Raden Oktova⁽¹⁾,
(1) 

Mukhtar Effendi⁽¹⁾, Hiroyuki Yokoi⁽²⁾, Nobutsuga Minami⁽³⁾, Eiji Kominama⁽⁴⁾, Shojiro Takeyama⁽⁵⁾,
(1) Physics Study Program, Jenderal Soedirman University Jl. dr. Soeparno No. 61 Purwokerto, Kode Pos 53123, Indonesia
(2) Graduate School of Science and Technology, Kumamoto University Kumamoto 862-8555, Japan
(3) Nanotechnology Research Institute,National Institute of Industrial Science and Technology Tsukuba, Ibaraki 305-8565, Japan
(4) The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
(5) The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan

Isa Akhlis⁽¹⁾,
(1) Jurusan Fisika, Universitas Negeri Semarang Kampus Sekaran, Gunungpati Semarang

T B Prayitno⁽¹⁾,
(1) Physics Department, Universitas Negeri Jakarta Jl. Pemuda Rawamangun No. 10