Browsing by Author "Yang, Chu Shou"

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Femtosecond Laser-Induced Formation of Wurtzite Phase ZnSe Nanoparticles in Air
(2012)
Wang, Hsuan I.
;
Tang, Wei Tsung
;
Liao, Li Wei
;
Tseng, Pei Shan
;
Luo, Chih Wei
We demonstrate an effective method to prepare wurtzite phase ZnSe nanoparticles from zincblende ZnSe single crystal using femtosecond pulse laser ablation. The fabricated ZnSe nanoparticles are in spherical shape and uncontaminated while synthesized under ambient environment. By controlling the laser fluences, the average size of ZnSe nanoparticles can be varied from similar to 16 nm to similar to 22 nm in diameter. In Raman spectra, the surface phonon mode becomes dominant in the smaller average particle size with uniform size distribution. The interesting phase transition from the zinc blende structure of ZnSe single crystal to wurtzite structure of ZnSe nanoparticles may have been induced by the ultrahigh ablation pressure at the local area due to the sudden injection of high energy leading to solid-solid transition.
Growth mechanism of CuZnInSe2 thin films grown by molecular beam epitaxy
(2013-09-01)
Tseng, Ya Hsin
;
Yang, Chu Shou
;
Wu, Chia Hsing
;
Chiu, Jai Wei
;
De Yang, Min
CuZnInSe2 (CZIS) has potential application in solar cell for absorption layer, and give an advantage to change the band gap from CuInSe2 (1.02 eV) to ZnSe (2.67 eV). Using molecular beam epitaxy technology, the CZIS thin films were grown via CuInSe (CIS) and ZnSe base. In the case of CIS, thin films were grown on Mo-coated soda lime glass with various zinc flux. CIS was transformed into chalcopyrite and sphalerite coexisting CZIS easily but it is difficult to transform into the pure sphalerite CZIS. Zn/(Zn+In+Cu) ratio has limited to approximate 36 at% and the excess-Zn played a catalyst role. In the case of ZnSe base, which was grown on GaAs (001), various In and Cu flux defined as the T-In series and T-Cu series, respectively. There are four types of compound in the T-In series and T-Cu series, including ZnSe, InxSey, ZnIn2Se4 (ZIS) and CZIS. In the T-In series under the lowest In and Cu flux, selenium (Se) were randomly combined with cations to form the CZIS. When T-In is increased in this moment, the CZIS was transformed into ZIS. In the T-Cu series, CZIS demonstrated via In-rich ZIS (Zn(In, Cu)Se) and InxSey base ((Zn, Cu)InSe). It is chalcopyrite and sphalerite coexisting structure in the medium T-Cu region. In the high T-Cu region, it is transformed into the Zn-poor and Cu-rich CZIS. (c) 2012 Elsevier B.V. All rights reserved.
Physical properties of InGaO3(ZnO)(m) with various content ratio grown by PAMBE
(2015-09-01)
Yang, Chu Shou
;
Huang, Shin Jung
;
Kao, Yu Chung
;
Chen, Guan He
;
Chou, Wu-Ching
The quaternary compound semiconductor (InGaO3(ZnO)(m)); m=1,2,3...)(IGZO) thin films were fabricated by plasma-assisted molecular beam epitaxy. First, the IGZO thin films were grown under the variation of gallium cell temperature to evaluate the fundamental properties of IGZO. A phase transformation between crystalline and amorphous is observed when the gallium content ratio is higher than 28 at%. It revealed redundancy in the metal, which would self-assist the channel or detect state to destroy the crystal structure. The highest mobility of 74.3 cm(2)/V s was obtained at 28 at% of gallium. By tuning the element content of quaternary compounds, the ternary plots distribution of IGZO thin films exhibits an amorphous structure in most regions. Therefore, the stoichiometric condition of IGZO, which is 1:1:1:4, is demonstrated at the amorphous structure. Additionally, it transitions to crystalline structure after a 1100 degrees C annealing process. (C) 2015 Elsevier B.V. All rights reserved.