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Copyright copy 2006 American Scientific PublishersAll rights reservedPrinted in the United States of America

Journal ofNanoscience and Nanotechnology

Vol 6 558ndash561 2006

Novel Growth of Aluminium Nitride Nanowires

M Radwanlowast and M BahgatCentral Metallurgical Research and Development Institute (CMRDI) PO Box 87 Helwan Cairo 11421 Egypt

This work describes novel growth of aluminium nitride (AlN) nanowires by nitridation of a mixtureconsists of aluminium and ammonium chloride powders (AlNH4Cl= 151 weight ratio) at 1000 Cfor 1 h in flowing nitrogen gas (1 lmin) XRD analysis of the product showed the formation of purehexagonal AlN SEM micrographs of as-synthesized product revealed the growth of homogeneousAlN nanowires ( 40ndash150 nm) No droplets were observed at the tips of obtained nanowires whichsuggests that they were grown mainly by a vapor-phase reactions mechanism Thermodynamicanalysis of possible intermediate reactions in the operating temperatures range illustrates that thesenanowires could be grown via spontaneous vapor-phase chlorination-nitridation sequences

Keywords AlN III-V Nitrides Nanowires Nitridation Vapor-Phase Growth

1 INTRODUCTION

Aluminium nitride (AlN) is a IIIndashV nitride-based semi-conductor with unique physical properties such as widebandgap high thermal conductivity high volume resistiv-ity low dielectric constant and a thermal expansion coeffi-cient matches that of silicon1ndash3 It is considered as an idealsubstrate and packaging material potential for advancedelectronic and optoelectronic devices AlN is also knownas interesting technical ceramics with good chemical sta-bility and high hardness and used in various structural andrefractory composites applications4

Many efforts have been spent on the development offibrous materials (whiskers wires pillars etc) because oftheir crystalline perfection and small dimensions whichoffers superior physical and chemical properties funda-mentally differs from their corresponding macro or bulkmaterials5 The fibers of AlN have attracted much atten-tion and there are several methods reported in the literaturefor their growth including (i) evaporation-condensationusing Al6 or AlN7ndash11 as source materials in high-puritynitrogen gas flow (ii) chemical vapor deposition usingaluminium halide-ammonia complexes at temperatures of750ndash1000 C1213 (iii) carbothermic reduction nitridationof alumina at about 1800 C in flowing nitrogen gas inpresence of catalysts14ndash16 or recently without catalyst17ndash18

(iv) flux growth at lower temperatures119 (vi) directnitridation of aluminium powder with aluminium chlo-ride promoter20ndash22 or alumina template23 at temperaturesof 1100ndash1250 C in flowing N2NH3 gas and (v) theself-propagating high-temperature synthesis of metallic Alpowder under pressurized nitrogen gas in presence of

lowastAuthor to whom correspondence should be addressed

additives24 However it is still difficult to state the tech-nique reasonable for the fabrication of homogeneous AlNfibers The current drawbacks are the application of hightemperatures (such as in methods i and iii) starting withcomplex (method ii) or expensive (method iv) precursorsor inconveniency for scaling up (methods ii and v) Onour experiments to prepare pure AlN nanopowders by thesimple direct nitridation method from metallic Al pow-der (180 micron in size) in a tube furnace at a relativelylow temperature (1000 C) in flowing N2 gas we acci-dentally observed the growth of unique particles-free AlNnanowires when an amount of ammonium chloride wasblended with Al reactant It has been published previ-ously that the addition of NH4Cl to starting Al powderenhances the nitridation rate and can promote the forma-tion of nanocrystalline AlN powders2526 but it has notbeen reported before to enhance the growth of fibrousforms The following sections describe the characteris-tics of produced AlN nanowires A proposed growthmechanism supported by a thermodynamic analysis willbe stated

2 EXPERIMENTAL DETAILS

The direct nitridation experiments were carried out in aporcelain boat (8 cm long) set in the center of an alu-mina tube (3 cm inner diameter and 100 cm long) mountedin a horizontal electric-resistance furnace The startingmaterials were commercially available aluminium pow-der with about 99 purity and an average particle sizeof 180 micron and a chemical-grade ammonium chloridepowder with minimum assay of 99 They were mixed(AlNH4Cl = 151 weight ratio) manually in agate mortarAbout 1 g of loose powder mixture was put into the boat

558 J Nanosci Nanotechnol 2006 Vol 6 No 2 1533-488020066558004 doi101166jnn2006102

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Radwan and Bahgat Novel Growth of Aluminium Nitride Nanowires

and placed in the alumina tube The system was flushedwith nitrogen gas for several minutes to remove any oxy-gen and moisture The nitrogen gas used was purified frommoisture by passing it through a silica gel tower The fur-nace was heated to 1000 C with a rate of 15 Cminunder nitrogen gas flow of 1 lmin and maintained for 1 hThen the boat was drawn to the end of the tube outsidethe heating furnace and kept for cooling down to roomtemperature under the nitrogen atmosphere The productwas observed visually and analyzed by X-ray diffraction(XRD BRUKER axcndashD8 Advance) using Cu-K radia-tion (40 kV40 mA) Morphology of as-synthesized AlNproduct was examined with scanning electron microscope(SEM JEOL-JSM-5410) Samples for SEM analyses werecoated with thin film of sputtered gold

3 RESULTS AND DISCUSSION

The synthesized AlN product consists of loose powderof white color Figure 1 shows the XRD pattern of thenitride product It is seen that the product is a purehexagonal AlN phase with traces of aluminium metalThe morphology of the as-synthesized AlN was investi-gated by SEM The product consists of particles-free AlNnanowires homogeneously distributed allover the sampleas in Figure 2(a) Most of the nanowires are straightalthough a variety of shapes such as kinks branches andtwining-plant-like has been observed in the same sampleas shown in Figure 2(bndashd) These wires have diametersof 40ndash150 nm and large aspect ratios (lengthdiameter)Some larger wires with a complicated shape have alsobeen found Figure 2(e) The tips of all wires did not showdroplets which may suggest that these nanowires weregrown probably by a vapor-phase reactions mechanism

2θ (degrees)

Inte

nsity

(ar

bitr

ary

units

)

20 25 30 35 4540 50 55 60 65 70 75 80

AlN (ge 96)

Al (le 4)

Fig 1 X-ray diffraction pattern of the as-synthesized product

(a) (b)

(c) (d)

(e)

Fig 2 SEM micrographs of the as-synthesized AlN nanowires withvarious shapes (a) particles-free homogeneous nanowires (b) kinks(c) branches (d) twining-plant-like and (e) complicated structures

The summary reaction of the direct nitridation of theAlndashNH4Cl mixture under flowing nitrogen gas can beexpressed as follows

Al+NH4Cl+ 12

N2 = AlN+NH3 +HCl

In which the ammonium chloride plays a critical role onthe growing of AlN nanowires The synthesis of these AlNnanowires implies that vapor-phase spontaneous reactionsand intermediate volatile species should be involved

During the nitridation experiments we observed thatlarge white vapors were evolved after the temperature rea-ched about 300 C This suggests that the beginning reac-tion will be the dissociation of ammonium chloride at alow temperature into volatile ammonia and hydrogen chlo-ride according to this reaction

NH4Cls = NH3g+HClg

Gaseous hydrogen chloride is very active and spontaneo-usly reacts with the aluminium particles and the followingintermediate reaction may occur

Alsl+3HClg = AlCl3g+32

H2g

The reaction system will contain many gaseous species(NH3g HClg H2g and AlCl3g) and when the AlCl3g

intermediate is mixed with the flowing nitrogen gas thepossible spontaneous vapor-phase nitridation reaction is

AlCl3g+12

N2g+32

H2g = AlNs+3HClg

Under a critical (low) supersaturation condition the AlNmolecules will be condensed in the form of nanowires

J Nanosci Nanotechnol 6 558ndash561 2006 559

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Novel Growth of Aluminium Nitride Nanowires Radwan and Bahgat

The above nitridation reaction regenerates gaseoushydrogen chloride which can be seen as the key interme-diate product essential to produce the volatile aluminiumchloride species and progress this chlorination-nitridationgrowth mechanism of AlN nanowires

There is another probable vapor-phase nitridation reac-tion which is thermodynamically spontaneous

AlCl3g+NH3g = AlNs+3HClg

Although the nitridation by ammonia is much spontaneousthan by nitrogen the major nitridation takes place by thelater one because this system yields nearly complete con-version of the aluminium powder into AlN wires while theamount of NH4Cl in the starting mixture is not enoughfor that Besides large ammonia-based white vapors wereobserved during the nitridation evolved from the system

In the work of Lu et al they utilized large amount ofammonium chloride (AlNH4Cl asymp16 weight ratio) andheated the mixture in closed system which resulted in thesynthesis of nanocrystalline AlN powder (6 nm)27 Basedon our growth model we think that their condition had pro-vided a high supersaturation environment which emergedhomogeneous nucleation in the vapor-phase and the con-densation of their AlN nanopowders

Figure 3 gives the Gibbs energy change of those inter-mediate reactions in the operating temperature range cal-culated from the NISTndashJANAF thermochemical data Itshows that the thermodynamic calculations are consis-tent with the above growth model in which the AlNnanowires were grown by the ammonium chloride assisteddirect nitridation of an aluminium powder under a

ndash400

ndash300

ndash200

ndash100

0

100

200

300

400

0 200 600 1000Temperature (˚C)

Gib

bs c

hang

e (k

Jm

ol)

h

g

fe

d

c

b

a

400 800

Fig 3 Gibbs energy change of possible intermediate reactionsa Al+3HCl=AlCl3+32H2 b Al+12N2 =AlN c Al+NH4Cl+12N2 =AlN+NH3+HCl d AlCl3+12N2+32H2 =AlN+3HCle AlCl3+NH3 =AlN+3 HCl f NH4Cl=NH3+HCl g AlCl3+NH4Cl=AlN+4 HCl h AlCl3+12N2 =AlN+32Cl2

flowing stream of nitrogen through spontaneous vapor-phase chlorination-nitridation sequences Growing of theseunique nanowires by this novel strategy will be of greatadvantageous because it enables the fabrication of finewires from cheap reactants by a much reasonable nitrida-tion condition compared to previous published reports2021

4 CONCLUSIONS

These results offer a new route for growing unique AlNnanowires by the direct nitridation of aluminium powdermixed with ammonium chloride (in 151 wt ratio) underisothermal heating at 1000 C for 1 h in flowing nitro-gen gas stream (1 lmin) The grown wires are mostlyparticles-free with nanometer dimensions (40ndash150 nm)The growth model consists of sequences of chlorination-nitridation intermediate reactions in the vapor-phase Ata critical low supersaturation condition nanowires of AlNwere deposited The summary reaction can be describedby the following reactions

NH4Cls = NH3g+HClg

Als l+3HClg = AlCl3g+32

H2g

AlCl3g+12

N2g+32

H2g = AlNs+3HClg

Acknowledgments M Radwan wishes to thankProfessor Y Miyamoto (JWRI Osaka Univ) for hisinvaluable advice during the progress of this work

References and Notes

1 C Wu Q Yang C Huang D Wang P Yin T Li and Y XieJ Solid State Chem 177 3522 (2004)

2 M E Levinshtein S L Rumyantsev and M S Shur John Wileyamp Sons Inc New York (2001) p 31

3 D K Gaskill C D Brandt and R J Nemanich in III-Nitride SiCand Diamond Materials for Electronic Devices Material ResearchSociety Symposium Proceedings Pittsburgh (1996) p 475

4 Q Hou R Mutharasan and M Koczak Mater Sci Eng A 195121 (1995)

5 A P Levitt Whisker Technology John Wiley amp Sons Inc NewYork (1970)

6 K M Taylor and C Lenie J Electrochem Soc 107 308 (1960)7 C M Drum and J W Mitchell Appl Phys Lett 4 164 (1964)8 G A Slack and T F McNelly J Cryst Growth 24 263 (1976)9 Y Wu W Miao and H Zhou Mater Chem Phys 69 186 (2001)10 H Cong H Ma and X Sun Phys B 323 354 (2002)11 B Liu J H Edgar Z Gu D Zhuang B Raghothamachar

M Dudley A Sarua M Kuball and H M Meyer III MRS InternetJ Nitride Semicond Res 96 (2004)

12 H Itoh H Morikawa and K Sugiyama J Cryst Growth 94 387(1989)

13 M Yoshioka N Takahashi and T Nakamura Mater Chem Phys86 74 (2004)

14 P G Caceres and H K Schmid J Am Ceram Soc 177 977(1994)

560 J Nanosci Nanotechnol 6 558ndash561 2006

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Radwan and Bahgat Novel Growth of Aluminium Nitride Nanowires

and placed in the alumina tube The system was flushedwith nitrogen gas for several minutes to remove any oxy-gen and moisture The nitrogen gas used was purified frommoisture by passing it through a silica gel tower The fur-nace was heated to 1000 C with a rate of 15 Cminunder nitrogen gas flow of 1 lmin and maintained for 1 hThen the boat was drawn to the end of the tube outsidethe heating furnace and kept for cooling down to roomtemperature under the nitrogen atmosphere The productwas observed visually and analyzed by X-ray diffraction(XRD BRUKER axcndashD8 Advance) using Cu-K radia-tion (40 kV40 mA) Morphology of as-synthesized AlNproduct was examined with scanning electron microscope(SEM JEOL-JSM-5410) Samples for SEM analyses werecoated with thin film of sputtered gold

3 RESULTS AND DISCUSSION

The synthesized AlN product consists of loose powderof white color Figure 1 shows the XRD pattern of thenitride product It is seen that the product is a purehexagonal AlN phase with traces of aluminium metalThe morphology of the as-synthesized AlN was investi-gated by SEM The product consists of particles-free AlNnanowires homogeneously distributed allover the sampleas in Figure 2(a) Most of the nanowires are straightalthough a variety of shapes such as kinks branches andtwining-plant-like has been observed in the same sampleas shown in Figure 2(bndashd) These wires have diametersof 40ndash150 nm and large aspect ratios (lengthdiameter)Some larger wires with a complicated shape have alsobeen found Figure 2(e) The tips of all wires did not showdroplets which may suggest that these nanowires weregrown probably by a vapor-phase reactions mechanism

2θ (degrees)

Inte

nsity

(ar

bitr

ary

units

)

20 25 30 35 4540 50 55 60 65 70 75 80

AlN (ge 96)

Al (le 4)

Fig 1 X-ray diffraction pattern of the as-synthesized product

(a) (b)

(c) (d)

(e)

Fig 2 SEM micrographs of the as-synthesized AlN nanowires withvarious shapes (a) particles-free homogeneous nanowires (b) kinks(c) branches (d) twining-plant-like and (e) complicated structures

The summary reaction of the direct nitridation of theAlndashNH4Cl mixture under flowing nitrogen gas can beexpressed as follows

Al+NH4Cl+ 12

N2 = AlN+NH3 +HCl

In which the ammonium chloride plays a critical role onthe growing of AlN nanowires The synthesis of these AlNnanowires implies that vapor-phase spontaneous reactionsand intermediate volatile species should be involved

During the nitridation experiments we observed thatlarge white vapors were evolved after the temperature rea-ched about 300 C This suggests that the beginning reac-tion will be the dissociation of ammonium chloride at alow temperature into volatile ammonia and hydrogen chlo-ride according to this reaction

NH4Cls = NH3g+HClg

Gaseous hydrogen chloride is very active and spontaneo-usly reacts with the aluminium particles and the followingintermediate reaction may occur

Alsl+3HClg = AlCl3g+32

H2g

The reaction system will contain many gaseous species(NH3g HClg H2g and AlCl3g) and when the AlCl3g

intermediate is mixed with the flowing nitrogen gas thepossible spontaneous vapor-phase nitridation reaction is

AlCl3g+12

N2g+32

H2g = AlNs+3HClg

Under a critical (low) supersaturation condition the AlNmolecules will be condensed in the form of nanowires

J Nanosci Nanotechnol 6 558ndash561 2006 559

RE

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CH

AR

TIC

LE

Novel Growth of Aluminium Nitride Nanowires Radwan and Bahgat

The above nitridation reaction regenerates gaseoushydrogen chloride which can be seen as the key interme-diate product essential to produce the volatile aluminiumchloride species and progress this chlorination-nitridationgrowth mechanism of AlN nanowires

There is another probable vapor-phase nitridation reac-tion which is thermodynamically spontaneous

AlCl3g+NH3g = AlNs+3HClg

Although the nitridation by ammonia is much spontaneousthan by nitrogen the major nitridation takes place by thelater one because this system yields nearly complete con-version of the aluminium powder into AlN wires while theamount of NH4Cl in the starting mixture is not enoughfor that Besides large ammonia-based white vapors wereobserved during the nitridation evolved from the system

In the work of Lu et al they utilized large amount ofammonium chloride (AlNH4Cl asymp16 weight ratio) andheated the mixture in closed system which resulted in thesynthesis of nanocrystalline AlN powder (6 nm)27 Basedon our growth model we think that their condition had pro-vided a high supersaturation environment which emergedhomogeneous nucleation in the vapor-phase and the con-densation of their AlN nanopowders

Figure 3 gives the Gibbs energy change of those inter-mediate reactions in the operating temperature range cal-culated from the NISTndashJANAF thermochemical data Itshows that the thermodynamic calculations are consis-tent with the above growth model in which the AlNnanowires were grown by the ammonium chloride assisteddirect nitridation of an aluminium powder under a

ndash400

ndash300

ndash200

ndash100

0

100

200

300

400

0 200 600 1000Temperature (˚C)

Gib

bs c

hang

e (k

Jm

ol)

h

g

fe

d

c

b

a

400 800

Fig 3 Gibbs energy change of possible intermediate reactionsa Al+3HCl=AlCl3+32H2 b Al+12N2 =AlN c Al+NH4Cl+12N2 =AlN+NH3+HCl d AlCl3+12N2+32H2 =AlN+3HCle AlCl3+NH3 =AlN+3 HCl f NH4Cl=NH3+HCl g AlCl3+NH4Cl=AlN+4 HCl h AlCl3+12N2 =AlN+32Cl2

flowing stream of nitrogen through spontaneous vapor-phase chlorination-nitridation sequences Growing of theseunique nanowires by this novel strategy will be of greatadvantageous because it enables the fabrication of finewires from cheap reactants by a much reasonable nitrida-tion condition compared to previous published reports2021

4 CONCLUSIONS

These results offer a new route for growing unique AlNnanowires by the direct nitridation of aluminium powdermixed with ammonium chloride (in 151 wt ratio) underisothermal heating at 1000 C for 1 h in flowing nitro-gen gas stream (1 lmin) The grown wires are mostlyparticles-free with nanometer dimensions (40ndash150 nm)The growth model consists of sequences of chlorination-nitridation intermediate reactions in the vapor-phase Ata critical low supersaturation condition nanowires of AlNwere deposited The summary reaction can be describedby the following reactions

NH4Cls = NH3g+HClg

Als l+3HClg = AlCl3g+32

H2g

AlCl3g+12

N2g+32

H2g = AlNs+3HClg

Acknowledgments M Radwan wishes to thankProfessor Y Miyamoto (JWRI Osaka Univ) for hisinvaluable advice during the progress of this work

References and Notes

1 C Wu Q Yang C Huang D Wang P Yin T Li and Y XieJ Solid State Chem 177 3522 (2004)

2 M E Levinshtein S L Rumyantsev and M S Shur John Wileyamp Sons Inc New York (2001) p 31

3 D K Gaskill C D Brandt and R J Nemanich in III-Nitride SiCand Diamond Materials for Electronic Devices Material ResearchSociety Symposium Proceedings Pittsburgh (1996) p 475

4 Q Hou R Mutharasan and M Koczak Mater Sci Eng A 195121 (1995)

5 A P Levitt Whisker Technology John Wiley amp Sons Inc NewYork (1970)

6 K M Taylor and C Lenie J Electrochem Soc 107 308 (1960)7 C M Drum and J W Mitchell Appl Phys Lett 4 164 (1964)8 G A Slack and T F McNelly J Cryst Growth 24 263 (1976)9 Y Wu W Miao and H Zhou Mater Chem Phys 69 186 (2001)10 H Cong H Ma and X Sun Phys B 323 354 (2002)11 B Liu J H Edgar Z Gu D Zhuang B Raghothamachar

M Dudley A Sarua M Kuball and H M Meyer III MRS InternetJ Nitride Semicond Res 96 (2004)

12 H Itoh H Morikawa and K Sugiyama J Cryst Growth 94 387(1989)

13 M Yoshioka N Takahashi and T Nakamura Mater Chem Phys86 74 (2004)

14 P G Caceres and H K Schmid J Am Ceram Soc 177 977(1994)

560 J Nanosci Nanotechnol 6 558ndash561 2006

RE

SE

AR

CH

AR

TIC

LE

Novel Growth of Aluminium Nitride Nanowires Radwan and Bahgat

The above nitridation reaction regenerates gaseoushydrogen chloride which can be seen as the key interme-diate product essential to produce the volatile aluminiumchloride species and progress this chlorination-nitridationgrowth mechanism of AlN nanowires

There is another probable vapor-phase nitridation reac-tion which is thermodynamically spontaneous

AlCl3g+NH3g = AlNs+3HClg

Although the nitridation by ammonia is much spontaneousthan by nitrogen the major nitridation takes place by thelater one because this system yields nearly complete con-version of the aluminium powder into AlN wires while theamount of NH4Cl in the starting mixture is not enoughfor that Besides large ammonia-based white vapors wereobserved during the nitridation evolved from the system

In the work of Lu et al they utilized large amount ofammonium chloride (AlNH4Cl asymp16 weight ratio) andheated the mixture in closed system which resulted in thesynthesis of nanocrystalline AlN powder (6 nm)27 Basedon our growth model we think that their condition had pro-vided a high supersaturation environment which emergedhomogeneous nucleation in the vapor-phase and the con-densation of their AlN nanopowders

Figure 3 gives the Gibbs energy change of those inter-mediate reactions in the operating temperature range cal-culated from the NISTndashJANAF thermochemical data Itshows that the thermodynamic calculations are consis-tent with the above growth model in which the AlNnanowires were grown by the ammonium chloride assisteddirect nitridation of an aluminium powder under a

ndash400

ndash300

ndash200

ndash100

0

100

200

300

400

0 200 600 1000Temperature (˚C)

Gib

bs c

hang

e (k

Jm

ol)

h

g

fe

d

c

b

a

400 800

Fig 3 Gibbs energy change of possible intermediate reactionsa Al+3HCl=AlCl3+32H2 b Al+12N2 =AlN c Al+NH4Cl+12N2 =AlN+NH3+HCl d AlCl3+12N2+32H2 =AlN+3HCle AlCl3+NH3 =AlN+3 HCl f NH4Cl=NH3+HCl g AlCl3+NH4Cl=AlN+4 HCl h AlCl3+12N2 =AlN+32Cl2

flowing stream of nitrogen through spontaneous vapor-phase chlorination-nitridation sequences Growing of theseunique nanowires by this novel strategy will be of greatadvantageous because it enables the fabrication of finewires from cheap reactants by a much reasonable nitrida-tion condition compared to previous published reports2021

4 CONCLUSIONS

These results offer a new route for growing unique AlNnanowires by the direct nitridation of aluminium powdermixed with ammonium chloride (in 151 wt ratio) underisothermal heating at 1000 C for 1 h in flowing nitro-gen gas stream (1 lmin) The grown wires are mostlyparticles-free with nanometer dimensions (40ndash150 nm)The growth model consists of sequences of chlorination-nitridation intermediate reactions in the vapor-phase Ata critical low supersaturation condition nanowires of AlNwere deposited The summary reaction can be describedby the following reactions

NH4Cls = NH3g+HClg

Als l+3HClg = AlCl3g+32

H2g

AlCl3g+12

N2g+32

H2g = AlNs+3HClg

Acknowledgments M Radwan wishes to thankProfessor Y Miyamoto (JWRI Osaka Univ) for hisinvaluable advice during the progress of this work

References and Notes

1 C Wu Q Yang C Huang D Wang P Yin T Li and Y XieJ Solid State Chem 177 3522 (2004)

2 M E Levinshtein S L Rumyantsev and M S Shur John Wileyamp Sons Inc New York (2001) p 31

3 D K Gaskill C D Brandt and R J Nemanich in III-Nitride SiCand Diamond Materials for Electronic Devices Material ResearchSociety Symposium Proceedings Pittsburgh (1996) p 475

4 Q Hou R Mutharasan and M Koczak Mater Sci Eng A 195121 (1995)

5 A P Levitt Whisker Technology John Wiley amp Sons Inc NewYork (1970)

6 K M Taylor and C Lenie J Electrochem Soc 107 308 (1960)7 C M Drum and J W Mitchell Appl Phys Lett 4 164 (1964)8 G A Slack and T F McNelly J Cryst Growth 24 263 (1976)9 Y Wu W Miao and H Zhou Mater Chem Phys 69 186 (2001)10 H Cong H Ma and X Sun Phys B 323 354 (2002)11 B Liu J H Edgar Z Gu D Zhuang B Raghothamachar

M Dudley A Sarua M Kuball and H M Meyer III MRS InternetJ Nitride Semicond Res 96 (2004)

12 H Itoh H Morikawa and K Sugiyama J Cryst Growth 94 387(1989)

13 M Yoshioka N Takahashi and T Nakamura Mater Chem Phys86 74 (2004)

14 P G Caceres and H K Schmid J Am Ceram Soc 177 977(1994)

560 J Nanosci Nanotechnol 6 558ndash561 2006

RE

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AR

CH

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Radwan and Bahgat Novel Growth of Aluminium Nitride Nanowires

15 H Zhou H Chen Y Wu W Miao and X Liu J Mater Sci 334249 (1998)

16 R Fu H Zhou L Chen and Y Wu Mater Sci Eng A 266 44(1999)

17 W Jung and S Ahn J Eur Ceram Soc 21 79 (2001)18 W Jung T J Lee and B Min Mater Lett 57 4237 (2003)19 C O Dugger Mater Res Bull 9 331 (1974)20 J A Haber N V Gunda and W E Buhro J Aerosol Sci 29 637

(1998)21 J A Haber P C Gibbons and W E Buhro Chem Mater 10 4062

(1998)

22 T Xie Y Lin G Wu X Yuan Z Jiang C Ye G Meng andL Zhang Inorganic Chem Commun 7 545 (2004)

23 Q Wu Z Hu X Wang Y Hu Y Tian and Y Chen DiamondRelated Mater 13 38 (2004)

24 H Wang J Han Z Li and S Du J Eur Ceram Soc 21 2193(2001)

25 Y Qiu and L Gao J Eur Ceram Soc 23 2015 (2003)26 V Rosenband and A Gany J Mater Process Technol 179

(2004)27 Q Lu J Hu K Tang Y Qian G Zhou X Liu and J Xing Chem

Lett 1239 (1999)

Received 1 August 2005 RevisedAccepted 4 August 2005

J Nanosci Nanotechnol 6 558ndash561 2006 561