scholarly journals Non-melt selective enhancement of crystalline structure in molybdenum thin films using femtosecond laser pulses

2021 ◽  
Vol 55 (11) ◽  
pp. 115301
Author(s):  
Ayesha Sharif ◽  
Nazar Farid ◽  
Mingqing Wang ◽  
Rajani K Vijayaraghavan ◽  
Kwang-Leong Choy ◽  
...  

Abstract It is challenging to crystalize a thin film of higher melting temperature when deposited on a substrate with comparatively lower melting point. Trading such disparities in thermal properties between a thin film and its substrate can significantly impede material processing. We report a novel solid-state crystallization process for annealing of high melting point molybdenum thin films. A systematic investigation of laser induced annealing from single pulse to high pulse overlapping is reported upon scanning at fluences lower than the threshold required for the damage/ablation of molybdenum thin films. The approach allows better control of the grain size by changing the applied laser fluence. Atomic force microscopy surface morphology and x-ray diffraction (XRD) analysis reveal significant improvements in the average polycrystalline grain size after laser annealing; the sheet resistance was reduced by 19% of the initial value measured by a Four-point probe system. XRD confirms the enlargement of the single crystal grain size. No melting was evident, although a change in the close packing, shape and size of nanoscale polycrystalline grains is observed. Ultrashort laser induced crystallinity greatly enhances the electrical properties; Hall measurements reinforced that the overall carrier concentration increases after scanning at different laser fluences. The proposed method, based on the aggregation and subsequent growth of polycrystalline and single crystal-grains, leading to enhanced crystallization, has potential to be applicable in thin film processing industry for their wide applications.

2021 ◽  
Vol 20 (2) ◽  
pp. 14-18
Author(s):  
Nur Afiqah Othman ◽  
Nafarizal Nayan ◽  
Mohd Kamarulzaki Mustafa ◽  
Zulkifli Azman ◽  
Megat Muhammad Ikhsan Megat Hasnan ◽  
...  

To date, the deposition of AlGaN thin film using the co-sputtering technique at room temperature has not been reported yet. The use of AlGaN for electronic devices has been widely known because of its ultra-wide bandgap. However, to deposit the AlGaN thin film and achieved high quality of AlGaN films, higher temperature or extra time deposition are needed, which is not compatible with industrial fabrication process. Here, a co-sputtering technique between two power supplies of magnetron sputtering (which are RF and HiPIMS) is introduced to deposit the AlGaN thin films. The AlGaN thin films were deposited at various RF power to study their effect on structural properties and morphology of the thin films. AlGaN films were sputtered simultaneously on silicon (111) substrate for short time and at room temperature using GaN and Al target. Then, the films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), and surface profiler to study their properties. XRD shows the GaN (101) and (013) plane for the AlGaN deposited at RF power of 30 W. Also there only GaN (101) for the AlGaN with 50 W RF power. Yet, the 70 W RF power shows the amorphous structure of AlGaN. The roughness and the grain size of AlGaN film from AFM analysis showed the trend of decreasing and increasing respectively. The roughness of the AlGaN films with 30 W power was 0.82 nm, 0.85 nm for 50 W, and 0.46 nm for 70 W RF power.  The grain size of the AlGaN films was 30.06 nm, 32.10 nm, and 37.65 nm for RF power of 30 W, 50 W, and 70 W respectively. The profilometer found that the thickness of the AlGaN films was decreasing with increasing of RF power. This paper can demonstrate a successful co-sputtering technique of AlGaN. Despite AlGaN crystal structure was not able to found out in the XRD analysis, the effect of RF power has been studied to give significant effects on AlGaN thin film deposition.


Coatings ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 23
Author(s):  
Weiguang Zhang ◽  
Jijun Li ◽  
Yongming Xing ◽  
Xiaomeng Nie ◽  
Fengchao Lang ◽  
...  

SiO2 thin films are widely used in micro-electro-mechanical systems, integrated circuits and optical thin film devices. Tremendous efforts have been devoted to studying the preparation technology and optical properties of SiO2 thin films, but little attention has been paid to their mechanical properties. Herein, the surface morphology of the 500-nm-thick, 1000-nm-thick and 2000-nm-thick SiO2 thin films on the Si substrates was observed by atomic force microscopy. The hardnesses of the three SiO2 thin films with different thicknesses were investigated by nanoindentation technique, and the dependence of the hardness of the SiO2 thin film with its thickness was analyzed. The results showed that the average grain size of SiO2 thin film increased with increasing film thickness. For the three SiO2 thin films with different thicknesses, the same relative penetration depth range of ~0.4–0.5 existed, above which the intrinsic hardness without substrate influence can be determined. The average intrinsic hardness of the SiO2 thin film decreased with the increasing film thickness and average grain size, which showed the similar trend with the Hall-Petch type relationship.


2010 ◽  
Vol 17 (05n06) ◽  
pp. 445-449 ◽  
Author(s):  
SUHUA FAN ◽  
QUANDE CHE ◽  
FENGQING ZHANG

The (100)-oriented Ca0.4Sr0.6Bi4Ti4O15(C0.4S0.6BTi ) thin film was successfully prepared by a sol-gel method on Pt/Ti/SiO2/Si substrate. The orientation and formation of thin films under different annealing schedules were studied using XRD and SEM. XRD analysis indicated that (100)-oriented C0.4S0.6BTi thin film with degree of orientation of I(200)/I(119) = 1.60 was prepared by preannealing the film at 400°C for 3 min followed by rapid thermal annealing at 800°C for 5 min. SEM analysis further indicated that the (100)-oriented C0.4S0.6BTi thin film with a thickness of about 800 nm was mainly composed of equiaxed grains. The remanent polarization and coercive field of the film were 16.1 μC/cm2 and 85 kV/cm, respectively.


2013 ◽  
Vol 802 ◽  
pp. 47-52
Author(s):  
Chuleerat Ibuki ◽  
Rachasak Sakdanuphab

In this work the effects of amorphous (glass) and crystalline (Si) substrates on the structural, morphological and adhesion properties of CoFeB thin film deposited by DC Magnetron sputtering were investigated. It was found that the structure of a substrate affects to crystal formation, surface morphology and adhesion of CoFeB thin films. The X-Ray diffraction patterns reveal that as-deposited CoFeB thin film at low sputtering power was amorphous and would become crystal when the power increased. The increase in crystalline structure of CoFeB thin film is attributed to the crystalline substrate and the increase of kinetic energy of sputtering atoms. Atomic Force Microscopy images of CoFeB thin film clearly show that the roughness, grain size, and uniformity correlate to the sputtering power and the structure of substrate. The CoFeB thin film on glass substrate shows a smooth surface and a small grain size whereas the CoFeB thin film on Si substrate shows a rough surface and a slightly increases of grain size. Sticky Tape Test on CoFeB thin film deposited on glass substrate indicates the adhesion failure with a high sputtering power. The results suggest that the crystalline structure of substrate affects to the atomic bonding and the sputtering power affects to intrinsic stress of CoFeB thin film.


Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 252 ◽  
Author(s):  
A. M. Alsaad ◽  
A. A. Ahmad ◽  
I. A. Qattan ◽  
Qais M. Al-Bataineh ◽  
Zaid Albataineh

Undoped ZnO and group III (B, Al, Ga, and In)-doped ZnO thin films at 3% doping concentration level are dip-coated on glass substrates using a sol-gel technique. The optical properties of the as-prepared thin films are investigated using UV–Vis spectrophotometer measurements. Transmittance of all investigated thin films is found to attain high values of ≥80% in the visible region. We found that the index of refraction of undoped ZnO films exhibits values ranging between 1.6 and 2.2 and approximately match that of bulk ZnO. Furthermore, we measure and interpret nonlinear optical parameters and the electrical and optical conductivities of the investigated thin films to obtain a deeper insight from fundamental and practical points of view. In addition, the structural properties of all studied thin film samples are investigated using the XRD technique. In particular, undoped ZnO thin film is found to exhibit a hexagonal structure. Due to the large difference in size of boron and indium compared with that of zinc, doping ZnO thin films with these two elements is expected to cause a phase transition. However, Al-doped ZnO and Ga-doped ZnO thin films preserve the hexagonal phase. Moreover, as boron and indium are introduced in ZnO thin films, the grain size increases. On the other hand, grain size is found to decrease upon doping ZnO with aluminum and gallium. The drastic enhancement of optical properties of annealed dip-synthesized undoped ZnO thin films upon doping with group III metals paves the way to tune these properties in a skillful manner, in order to be used as key candidate materials in the fabrication of modern optoelectronic devices.


Solar Energy ◽  
2005 ◽  
Author(s):  
Gye-Choon Park ◽  
Woon-Jo Jeong ◽  
Hyeon-Hun Yang ◽  
Hae-Duck Jung ◽  
Jin Lee ◽  
...  

CuInS2 thin films were fabricated by sulphurization of S/In/Cu Stacked elemental layers (SEL) on slide glass substrates by annealing in vacuum of 10−3 Torr at temperature of 50 °C ∼ 350 °C. Some S/In/Cu SEL were vacuum annealed under a sulfur atmosphere. The thin films thus annealed were analyzed by measuring structural, electrical and optical properties. When CuInS2 thin films were made under a sulfur atmosphere, lattice constant of a and grain size of the thin film were a little larger than those in only vacuum annealing. The largest lattice constant of a and grain size was 5.63 Å and 1.2 μm respectively. Also, when the thin films were made under a sulfur atmosphere, conduction types were all p-type with resistivities of around 10−1 Ωcm and optical energy band gaps of the films were a little larger than those in only vacuum and the largest optical energy band gap of CuInS2 thin film was 1.53 eV.


2009 ◽  
Vol 60-61 ◽  
pp. 430-434 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun ◽  
Guo Qiang Wu

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.


2021 ◽  
Vol 21 (3) ◽  
pp. 1971-1977
Author(s):  
Jihye Kang ◽  
Dongsu Park ◽  
Donghun Lee ◽  
Masao Kamiko ◽  
Sung-Jin Kim ◽  
...  

In this research, alternative deposition process of ZnO-based thin films have been studied for transparent conducting oxide (TCO) application. To improve the electrical and optical properties of transparent oxide thin films, alternatively stacked Al-doped ZnO and In-doped ZnO thin films were investigated. Multilayer structure of alternative 6 layers of thin films were prepared in this research. Especially, Aluminum and Indium were chosen as dopant materials. Thin films of Al-doped ZnO (AZO) and In-doped ZnO (IZO) were alternatively deposited by spin coating with sol-gel method. After deposition of multilayered thin films, multi steps of furnace (F), rapid thermal annealing (R) and CO2 laser annealing (L) processes were carried out and investigated thin film properties by dependence of post-annealing sequence and thin film structures. The electrical and optical properties of thin films were investigated by 4-point probe and UV-vis spectroscopy and its shows the greatest sheet resistance value of 0.59 kΩ/sq. from AZO/IZO multilayered structure and upper 85% of transmittance. The structural property and surface morphology were measured by X-Ray Diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The Al- and In-doped ZnO thin film shows the highest intensity value at (002) peak of AZO/IZO multilayer structure which was performed FRL process.


2010 ◽  
Vol 638-642 ◽  
pp. 2909-2914 ◽  
Author(s):  
Yuichi Sato ◽  
Tatsushi Kodate ◽  
Manabu Arai

Thin films of CdTe semiconductors were prepared on sapphire single crystal and quartz glass substrates by a vacuum evaporation method. Crystallinity and photoluminescence properties of the obtained CdTe thin films on the substrates were semi-quantitatively compared concerning the difference of the substrate materials. Dependences of the properties on the substrate temperature in the preparations and indium doping to the thin films were also investigated.


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