Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate
© Ghazali et al.; licensee Springer. 2014
Received: 24 October 2014
Accepted: 9 December 2014
Published: 18 December 2014
Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.
KeywordsElectrochemical deposition Gallium oxide Gallium nitride Nanostructure Nitridation
Gallium nitride (GaN) is a very hard, chemically and mechanically stable wide bandgap (3.4 eV) semiconductor material with high heat capacity and thermal conductivity which makes it suitable to be used for sensors [1–8], high power electronic devices such as field-effect transistor (FET)  and optoelectronic devices such as light-emitting diode (LED) . Up to this date, many techniques have been explored to synthesize GaN nanostructures including nanowires, nanorods, nanodots and so forth since such low-dimensional nanostructures are promising for increasing the performance optoelectronic devices and the sensitivity of sensors [11, 12]. For example, GaN nanorods and nanowires have been applied for chemical sensing application as reported by Wright et al.  and Huang Y et al. , respectively, due to a large surface to volume ratio. GaN nanodots have been used in photodetectors as reported by Kumar et al..
Recently, GaN on silicon carbide (SiC) or sapphire substrate have been widely used for several specific electronic applications. However, these substrates are expensive and not available in large wafer size . According to Kukushkin et al., Si substrate seems to be more preferable for the heterostructure growth of GaN due to the availability of Si in large wafer size, the low price of Si and the maturity of Si-based technology . In addition, the integration of GaN-based devices on Si platform seems to be very attractive for the hybrid integration towards ‘More than Moore’ technology . Several vapor-phase techniques have been reported for growing GaN nanostructures directly on Si with high quality which include molecular beam epitaxy (MBE) , metal-organic chemical vapor deposition (MOCVD)  and hydride vapor phase epitaxy (HVPE) . However, these vapor-phase techniques are too expensive and their growth parameters are quite complicated. In recent years, a transformation of the grown gallium oxide (Ga2O3) structures on Si to GaN by a so-called nitridation seems to be a simple method to create a GaN/Si heterostructure . Here, a nitridation is achieved by annealing the Ga2O3 structures in ammonia gas. Li et al. reported the repeatable transformation of the CVD-grown GaN structures to Ga2O3 structures by an annealing in air and back to GaN structures by an annealing in ammonia . Moreover, there are several studies reporting the formation of GaN nanostructures by annealing the sputtered Ga2O3 layer on metal-coated Si substrates in ammonia [24–27]. To our knowledge, the nitridation of the electrochemically deposited Ga2O3 structures on bare Si substrates to form GaN nanostructures without the assistance of metal catalyzers does not appear in the published literature.
Recently, we report the growth of Ga2O3 nanostructures directly on Si without any assistance of metal catalyzer by using a simple electrochemical deposition . This liquid-phase technique provides several advantages such as high controllability of thickness and morphologies of Ga2O3 nanostructures due to a less number of growth parameters. In this work, we investigate the formation of GaN nanostructures by ammoniating the electrochemically deposited β-Ga2O3 nanostructures on Si substrate. Up to this date, no such similar work is reported where a combination of liquid-phase and vapor-phase methods is utilized to form a GaN/Si heterostructure. The effects of the ammoniating times and temperatures were studied. The mechanism for the growth of GaN was proposed and discussed.
The electrochemically deposited Ga2O3 was ammoniated in a quartz tube furnace as shown in Figure 1b, at various times of 15, 30 and 45 min and temperatures of 800°C, 850°C and 900°C under a flow of ammonia (NH3) gas of 100 sccm at atmospheric pressure. The timing chart of ammoniating process is shown in Figure 1c. Before starting the ammoniating process, the sample was put inside the quartz tube furnace and then the nitrogen (N2) gas was purged for 10 min to flush out the air in the quartz tube. After that, the temperature was increased up to the setting temperatures, i.e. 800°C, 850°C and 900°C from room temperature (RT) with a ramping rate of 28°C/min. After reaching the setting temperature, N2 gas was stopped and NH3 gas was introduced into the furnace. The furnace was immediately switched off upon reaching the setting ammoniating time. At the same time, NH3 gas was immediately stopped and N2 gas was purged back into the furnace for 1 h to remove the remaining NH3 gas during the cooling down process. The ammoniated structures were characterized using field-emission scanning electron microscopy (FESEM; Hitachi SU8083, Hitachi, Ltd, Chiyoda-ku, Japan), energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD; Bruker D8 Advance, Bruker AXS, Inc., Yokohama-shi, Japan).
Results and discussion
The nitridation of the electrochemically grown Ga2O3 nanostructures to form GaN nanostructures on Si platform have been studied by varying the ammoniating times and temperatures. The complete transformation of Ga2O3 nanorods to h-GaN nanowires was achieved at 900°C with a short ammoniating time of 15 min. The obtained results suggest that the effect of the ammoniating temperature in realizing a complete transformation is more prominent than the ammoniating time. Form the proposed growth mechanism, it was found that a complete transformation to GaN nanostructures can not be realized without a complete deoxidization of Ga2O3. In a complete transformation process, it seems to show the occurence of morphological change. The presented method seems to be promising for the formation of h-GaN nanostructures on Si for the applications in sensing and optoelectronics.
The authors would like to thank for the supports provided by MIMOS Berhad and Universiti Sains Malaysia. N. M. Ghazali thanks Malaysia-Japan International Institute of Technology (MJIIT) for the scholarship. This work was supported by Nippon Sheet Glass Corp, Hitachi Foundation, MJIIT, universiti Teknologi Malaysia, Malaysian Ministry of Education and Malaysian Ministry of Science, Technology and Innovation through various research grants.
- Abidin MSZ, Shahjahan , Hashim AM: Surface reaction of undoped AlGaN/GaN HEMT based two terminal device in H+ and OH-ion-contained aqueous solution. Sains Malaysiana 2013, 2: 197–203.Google Scholar
- Abidin MSZ, Hashim AM, Sharifabad ME, Rahman SFA, Sadoh T: Open-gated pH sensor fabricated on an undoped-AlGaN/GaN HEMT structure. Sensors 2011, 11: 3067–3077. 10.3390/s110303067View ArticleGoogle Scholar
- Mohamad M, Mustafa F, Rahman SFA, Abidin MSZ, Ali NK, Hashim AM, Aziz AA, Hashim MR: The sensing performance of hydrogen gas sensor utilizing undoped-AlGaN/GaN HEMT. J Appl Sci 2010, 16: 1797–1801.Google Scholar
- Pearton SJ, Fan R: Gallium nitride-based gas, chemical and biomedical sensors. Instrum Meas Mag IEEE 2012, 15: 16–21.View ArticleGoogle Scholar
- Chu BH, Sam Kang BS, Hung SC, Chen KH, Ren F, Sciullo A, Gila BP, Pearton SJ: Aluminum gallium nitride (GaN)/GaN high electron mobility transistor-based sensors for glucose detection in exhaled breath condensate. J Diabetes Sci Technol 2010, 4: 171–179. 10.1177/193229681000400122View ArticleGoogle Scholar
- Chitara B, Late DJ, Krupanidhi SB, Rao CNR: Room-temperature gas sensors based on gallium nitride nanoparticles. Solid State Commun 2010, 150: 2053–2056. 10.1016/j.ssc.2010.08.007View ArticleGoogle Scholar
- Schalwig J, Muller G, Ambacher O, Stutzman M: Group III-nitride based gas sensing devices. Phys Stat Sol (a) 2001, 185: 39–45. 10.1002/1521-396X(200105)185:1<39::AID-PSSA39>3.0.CO;2-GView ArticleGoogle Scholar
- Lee DS, Lee JH, Lee YH, Lee DD: GaN thin films as gas sensors. Sensor Actuat B Chem 2003, 6989: 1–6.View ArticleGoogle Scholar
- Micovic M, Hashimoto P, Hu M, Milosavljevic I, Duvall J, Willadesen PJ, Wong WS, Conway AM, Kurdoghlian A, Deelman PW, Moon JS, Schmitz A, Delaney MJ: GaN double heterojunction field effect transistor for microwave and millimeterwave power applications. IEDM Technical Digest 2004, 33: 807–810.Google Scholar
- Choi JH, Zoulkarneev A, Kim S, Baik CW, Yang MH, Park SS, Suh H, Kim UJ, Son HB, Lee JS, Kim M, Kim JM, Kim K: Nearly singe-crystalline GaN light-emitting diodes on amorphous glass substrates. Nat Photonics 2011, 5: 763–769. 10.1038/nphoton.2011.253View ArticleGoogle Scholar
- Kang MS, Lee CH, Park JB, Yoo H, Yi GC: Gallium nitride nanostructures for light-emitting diode application. Nano energy 2012, 1: 391–400. 10.1016/j.nanoen.2012.03.005View ArticleGoogle Scholar
- Shur MS: GaN based transistors for high power applications. Solid State Electron 1998, 42: 2131–2138. 10.1016/S0038-1101(98)00208-1View ArticleGoogle Scholar
- Wright JS, Lim W, Norton DP, Pearton SJ, Ren F, Johnson JL, Ural A: Nitride and oxide semiconductor nanostructured hydrogen gas sensors. Semicond Sci Technol 2010, 25: 1–8.View ArticleGoogle Scholar
- Huang Y, Duan X, Cui Y, Lieber CM: Gallium nitride nanowire nanodevices. Nano Lett 2012, 2: 101–104.View ArticleGoogle Scholar
- Kumar M, Roul B, Bhat TN, Rajpalke MK, Krupanidhi SB: Structural characterization and ultraviolet photoresponse of GaN nanodots grown by molecular beam epitaxy. Appl Phy Express 2012, 5: 1–3.Google Scholar
- Pal S, Jacob C: Silicon-a new substrate for GaN growth. Bull Mater Sci 2004, 27: 501–504. 10.1007/BF02707276View ArticleGoogle Scholar
- Kukushkin SA, Osipov AV, Bessolov VN, Medvedev BK, Nevolin VK, Tcarik KA: Substrate for epitaxy of gallium nitride–new material and technique. Rev Adv Mater Sci 2008, 17: 1–32.Google Scholar
- Takagi S, Sugiyama M, Yasuda T, Takenaka M: Ge/III-V channel engineering for future CMOS. ECS Trans 2009, 5: 9–20.View ArticleGoogle Scholar
- Calarco R, Meijers RJ, Debnath RK, Stoica T, Sutter E, Lu H: Nucleation and growth of GaN nanowires on Si (111) performed by molecular beam epitaxy. Nano Lett 2007, 7: 2248–2251. 10.1021/nl0707398View ArticleGoogle Scholar
- Haffouz S, Kirilyuk V, Hageman PR, Macht L, Weyher JL, Larsen PK: Improvement of the optical properties of metalorganic chemical vapor deposition grown on GaN on sapphire by an in situ SiN treatment. Appl Phys Lett 2001, 79: 2390–2392. 10.1063/1.1409277View ArticleGoogle Scholar
- Paskova T, Darakchieva V, Valcheva E, Paskov PP, Ivanov IG, Monemar B, Bottcher T, Roder C, Hommel D: Hydride vapor-phase epitaxial GaN thick films for quasi substrate applications. J Electron Matter 2004, 33: 389–394. 10.1007/s11664-004-0189-4View ArticleGoogle Scholar
- Yam FK, Low LL, Oh SA, Hassan Z: Gallium nitride: an overview of structural defects. In Optoelectronic Materials and Technique. Edited by: Predeep P. Malaysia: InTech publication; 2011:99–137.Google Scholar
- Li J, An L, Lu C, Liu J: Conversion between hexagonal GaN and β-Ga2O3 nanowires and their electrical transport properties. Nano Lett 2006, 6: 148–152. 10.1021/nl051265kView ArticleGoogle Scholar
- Qin LX, Xue CS, Zhuang HZ, Yang ZZ, Li H, Chen JH, Wang Y: Influence of ammoniating temperature on co-catalyzed GaN nanowires. Appl Phys A 2008, 91: 675–678. 10.1007/s00339-007-4358-1View ArticleGoogle Scholar
- Shi F, Wang Y, Xue C: Synthesis of GaN nanowires by CVD method: effect of reaction temperature. J Exp Nanosci 2011, 6: 238–247. 10.1080/17458080.2010.493183View ArticleGoogle Scholar
- Zhuang H, Wang J, Zhang X, Li J: Influence of ammoniating time on Nb-catalyzed GaN nanostructured materials. Int J Nanosci 2011, 10: 1209–1214. 10.1142/S0219581X11008290View ArticleGoogle Scholar
- Xue C, Wu Y, Zhuang H, Tian D, Liu Y, He J, Al Y, Sun L, Wang F: Fabrication and photoluminescence of GaN nanowires prepared by ammoniating Ga2O3/BN films on Si substrate. Chin Sci Bull 2006, 51: 1662–1665. 10.1007/s11434-006-2042-zView ArticleGoogle Scholar
- Ghazali NM, Mahmood MR, Yasui K, Hashim AM: Electrochemically deposited gallium oxide nanostructures on silicon substrates. Nanoscale Res Lett 2014, 9: 120. 10.1186/1556-276X-9-120View ArticleGoogle Scholar
- Xia QL, Shan XC, Zhao ZH, Zhu YZ, Hua CJ, Hong L: Synthesis of large-scale GaN nanowires by ammoniating Ga2O3 films on co layer deposited on Si (111) substrates. Chin Phys Soc 2008, 17: 2180–2183. 10.1088/1674-1056/17/6/040View ArticleGoogle Scholar
- Kim HW, Myung JH, Shim SH: A study of Ga2O3 nanomaterials synthesized by the thermal evaporation of GaN powders. Mater Sci Forum 2006, 510: 654–657.View ArticleGoogle Scholar
- Li D, Wang F, Zhu J, Liu D, Wang X, Xiang L: Microwave hydrothermal synthesis of GaN nanorods. Mater Sci Forum 2011, 675: 251–254.View ArticleGoogle Scholar
- Luo L, Yu K, Zhua Z, Zhang Y, Ma H, Xue C, Yang Y, Chen S: Field emission from GaN nanobelts with Herringbone morphology. Mater Lett 2004, 58: 2893–2896. 10.1016/j.matlet.2004.05.014View ArticleGoogle Scholar
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