Name: synthesis and characterization of high c-axis zno thin film by plasma enhanced chemical vapor deposition system and its uv photodetector application
Uploaded: 2015-10-03T14:00:00
Description: Watch this Scientific Journal Video about Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application at JoVE.c

This work was financially supported of by the Ministry of Science and Technology and National Science Council of Republic of China (contract nos. NSC 101-2221-E-027-042 and NSC 101-2622-E-027-003-CC2). D. H. Wei thanks the National Taipei University of Technology (TAIPEI TECH) for the Dr. Shechtman Prize Award.

1. Substrate Preparation and Cleaning
<ol>
	<li>Cut 10 mm x 10 mm silicon substrates from Si(100) wafer.</li>
	<li>Cut 10 mm x 10 mm glass substrates.</li>
	<li>Use ultrasonic cleaner to clean the silicon and glass substrates with acetone for 10 min, alcohol for 10 min, and then isopropanol for 15 min.</li>
	<li>Rinse the substrates with deionized (DI) water three times.</li>
	<li>Blow-dry the substrates with a nitrogen gun.</li>
</ol>
2. DEZn Preparation and Preservation
<p class="jove_conten...

<ol>
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K., Yao, T. a. k. a. f. u. m. i. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MBE+growth+of+high-quality+ZnO+films+on+epi-GaN.">MBE growth of high-quality ZnO films on epi-GaN.</a> J. Cryst. Growth. 209, 816-821 (2000).</li><li>Park, D. J., Lee, J. Y., Park, T. E., Kim, Y. Y., Cho, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+microstructural+properties+of+a+ZnO+thin+film+using+a+buffer+layer+in-situ+annealed+in+argon+ambient.">Improved microstructural properties of a ZnO thin film using a buffer layer in-situ annealed in argon ambient.</a> Thin Solid Films. 515, 6721-6725 (2000).</li><li>Kim, M. 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F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=superhigh+gain+visible-blind+UV+detector+and+optical+logic+gates+based+on+nonpolar+a-axial+GaN+nanowire.">superhigh gain visible-blind UV detector and optical logic gates based on nonpolar a-axial GaN nanowire.</a> Nanoscale. 6, 12009-12017 (2014).</li><li>Inamdar, S. I., Rajpure, K. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-performance+metal-semiconductor-metal+UV+photodetector+based+on+spray+deposited+ZnO+thin+films.">High-performance metal-semiconductor-metal UV photodetector based on spray deposited ZnO thin films.</a> J. Alloy. Compd. 595, 55-59 (2014).</li><li>Tian, C. 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K., Srinivasulu Naidu, ., S, S., Uthanna, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+substrate+temperature+on+the+physical+properties+of+DC+reactive+magnetron+sputtered+ZnO+films.">Effect of substrate temperature on the physical properties of DC reactive magnetron sputtered ZnO films.</a> Opt. Mater. 13, 239-247 (1999).</li><li>Iwanaga, H., Kunishige, A., Takeuchi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anisotropic+thermal+expansion+in+wurtzite-type+crystals.">Anisotropic thermal expansion in wurtzite-type crystals.</a> J. Mater. 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Critical steps and modifications
In step 1, the substrates should be thoroughly cleaned and steps 1.3 to 1.5 followed to make sure that there is no grease or organic and inorganic contaminations on the substrates. Any grease or organic and inorganic contaminations on the substrate surface will significantly reduce the adhesion of the film.
Step 2 is the most important procedure before the ZnO film preparation process. DEZn is very toxic and violently reacts with wat...

ZnO is a promising wide-band-gap functional semiconductor material due to its unique properties such as high chemical stability, low cost, non-toxicity, low power threshold for optical pumping, wide direct band gap (3.37 eV) at RT and large exciton binding energy of ~60 meV 1-2. Recently, ZnO thin films have been employed in many application fields including transparent conductive oxide (TCO) films, blue light emitting device, field-effect transistors, and gas sensor 3-6. On the other hand, ZnO is a candidate material to replace indium tin oxide (ITO) owing to indium and tin being rare and expensive. Moreover, ZnO possesses&#160;high optical transmittance in the visible wavelength region and low resistivity compared with ITO films 7-8. Accordingly, fabrication, characterization and application of ZnO has been extensively reported. This present study focuses on synthesizing high c-axis (0002) ZnO thin films by a simple and effectively method and its practical application towards a UV photodetector.
The recent research report findings indicate that the high quality ZnO thin film could be synthesized by various techniques such as sol-gel method, radio frequency magnetron sputtering, metal organic chemical vapor deposition (MOCVD), and so on 9-14. Each technique has its advantages and disadvantages. For example, a principal advantage of sputtering deposition is that target materials with very high melting point are effortlessly sputtered onto the substrate. In contrast, the sputtering process is difficult to combine with a lift-off for structuring the film. In our study, the plasma enhanced chemical vapor deposition (PECVD) system was employed to synthesize high quality c-axis ZnO thin films. Plasma bombardment is a key factor in the synthesizing process that can increase the thin film density and enhance the ion decomposition reaction rate 15. In addition, the high growth rate and large-area uniform deposition are other distinctive advantages for PECVD technique.
Except for the synthesis technique, the good adhesion on the substrate is another considered issue. In many studies, the c-plane sapphire has been widely used as the substrate to synthesize high c-axis ZnO thin films because the ZnO and sapphire have the same hexagonal lattice structure. However, the ZnO was synthesized on sapphire substrate exhibiting rough surface morphology and high residual (defect-related) carrier concentrations due to the large lattice misfits between the ZnO and c-plane sapphire (18%) oriented in the in-plane direction 16. Compared with the sapphire substrate, a Si wafer is another widely used substrate for the ZnO synthesis. Si wafers have been extensively used in semiconductor industry; and thus, growth of high quality ZnO thin films on Si substrates is very important and necessary. Unfortunately, the crystal structure and thermal expansion coefficient between the ZnO and Si are obviously different leading to deterioration of crystal quality. Over past decade, great efforts have been made to improve the quality of ZnO thin films onto Si substrates by using various methods including ZnO buffer layers 17, annealing in various gas atmosphere 18, and passivation of the Si substrate surface 19. The present study successfully offered a simple and effectively method to synthesize high c-axis ZnO thin film onto Si substrates without any buffer layer or pre-treatment. The experiment results indicated that the ZnO thin films synthesized under the optimal growth temperature showed the good crystal and optical qualities. The crystalline structure, RF plasma composition, surface morphology, and optical properties of ZnO thin films were investigated by X-ray diffraction (XRD), optical emission spectroscopy (OES), field emission scanning electron microscopy (FE-SEM), and RT photoluminescence (PL) spectra, respectively. Moreover, the transmittance of ZnO thin films was also confirmed and reported.
The as-synthesized ZnO thin film served as a sensing layer for UV photodetector application was also investigated in this study. The UV photodetector has great potential applications in UV monitoring, optical switch, flame alarm, and missile warming system 20-21. There are many types of photodetectors which have been carried out such as positive intrinsic negative (p-i-n) mode and metal-semiconductor-metal (MSM) structures including Ohmic contact and Schottky contact. Each type has its own advantages and drawbacks. Currently, MSM photodetector structures have attracted intensive interest due to their outstanding performance in responsivity, reliability and response and recovery time 22-24. The results presented here have shown that the MSM Ohmic contact mode was employed to fabricate ZnO thin film based UV photodetector. Such a kind of photodetector typically reveals a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>RF power supply</td>
			<td>ADVANCED ENERGY</td>
			<td>RFX-600</td>
			<td></td>
		</tr>
		<tr>
			<td>Butterfly valve</td>
			<td>MKS</td>
			<td>253B-1-40-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Mass flow conctroller</td>
			<td>PROTEC INSTRUMENTS</td>
			<td>PC-540</td>
			<td></td>
		</tr>
		<tr>
			<td>Pressure conctroller</td>
			<td>MKS</td>
			<td>600 series&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Heater</td>
			<td>UPGRADE INSTRUMENT CO.</td>
			<td>UI-TC 3001</td>
			<td></td>
		</tr>
		<tr>
			<td>Sputter gun</td>
			<td>AJA INTERNATIONAL</td>
			<td>A320-HA</td>
			<td></td>
		</tr>
		<tr>
			<td>DEZn 1.5M</td>
			<td>ACROS ORGANIC USA, New Jersey</td>
			<td></td>
			<td>also called Diethylzinc (C2H5)2Zn</td>
		</tr>
		<tr>
			<td>Spin coater&#160;</td>
			<td>SWIENCO</td>
			<td>PW - 490</td>
			<td></td>
		</tr>
		<tr>
			<td>I-V measurement</td>
			<td>Keithley</td>
			<td>Model: 2400</td>
			<td></td>
		</tr>
		<tr>
			<td>Photocondutive measurement&#160;</td>
			<td>Home-built</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>UV light sourse</td>
			<td>Panasonic</td>
			<td>ANUJ 6160</td>
			<td></td>
		</tr>
		<tr>
			<td>Mask aligner</td>
			<td>Karl Suss</td>
			<td>MJB4</td>
			<td></td>
		</tr>
		<tr>
			<td>Photoresist</td>
			<td>Shipley a Rohm &#38; Haas company</td>
			<td>S1813</td>
			<td></td>
		</tr>
		<tr>
			<td>Developer</td>
			<td>Shipley a Rohm &#38; Haas company</td>
			<td>MF319</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon wafer</td>
			<td>E-Light Technology Inc</td>
			<td>12/0801</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass substrate</td>
			<td>CORNING</td>
			<td>1737</td>
			<td>P-type / Boron</td>
		</tr>
	</tbody>
</table>

synthesis and characterization of high c-axis zno thin film by plasma enhanced chemical vapor deposition system and its uv photodetector application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.
For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.

The ZnO (0002) thin films with high c-axis preferred orientation have been successfully synthesized onto the Si substrates by using the PECVD system. The carbon dioxide (CO2) and the diethylzinc (DEZn) were used as oxygen and zinc precursors, respectively. The crystal structure of ZnO thin films was characterized by X-ray diffraction (Figure 4), indicating that the ZnO thin film synthesized at 400 oC with the strongest (0002) diffraction peak. When the synthesized temperatu...

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Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

We offered a method to directly synthesize high c-axis (0002) ZnO thin film by plasma enhanced chemical vapor deposition. The as-synthesized ZnO thin film combined with Pt interdigitated electrode was used as sensing layer for ultraviolet photodetector, showing a high performance through a combination of its good responsivity and reliability.

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto ...

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Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Well-aligned Vertically Oriented ZnO Nanorod Arrays and their Application in Inverted Small Molecule Solar Cells

This manuscript describes how to design and fabricate efficient inverted solar cells, which are based on a two-dimensional conjugated small molecule ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Bulk and Thin Film Synthesis of Compositionally Variant Entropy-stabilized Oxides

Here, we present a procedure for the synthesis of bulk and thin film multicomponent (Mg0.25(1-x)CoxNi0.25(1-x)Cu0.25(1-x)Zn0.25(1-x))O (Co variant) and ...

Film Control to Study Contributions of Waves to Droplet Impact Dynamics on Thin Flowing Liquid Films

Droplet impact is a very common phenomenon in nature and attracts attention due to its aesthetic fascination and wide-ranging applications. Previous ...