Synthesis, Morphology and Optical Properties of GaN

th 58

DAE Solid State Physics Symposium 2013 (DAESSPS2013) Thapar University, Patiala, Punjab, India.

Synthesis, Morphology and Optical Properties of GaN and AlGaN Semiconductor Nanostructures B. Kuppulingam, Shubra Singh, K. Baskar* Crystal Growth Centre, Anna University, Chennai-25.

Paper No. J-125

E-mail: [email protected]

Flow chart for synthesis of GaN and AlGaN nanoparticles

Introduction  Gallium Nitride (GaN) and Aluminum Nitride (AlN) are III–V Nitrides with a direct bandgap of 3.4 eV and 6.2 eV respectively at room temperature  Among the ternary metal nitrides, growth of AlGaN has attracted interest in recent years as bandgap can be tuned from 3.4 to 6.2 eV  AlGaN useful to fabricate UV light emitting diodes (LEDs), laser diodes, high power and high temperature electronic devices Wurtzite Nitrides

GaN

AlN

InN

Band gap (eV)

3.44

6.20

0.7

Lattice Constant (Å) a= 3.189 c= 5.185 Melting Point

>2500°C

a= 3.112 c= 4.982 2200°C

a=3.548 c=5.760 1100°C

GaCl3, AlCl3, EDTA, NH3

2Ga-EDTA.NH4→ Ga2O3+EDTAfragments Ga2O3+2NH3→2GaN+3H2O

Stirred for 6 hours AlxGa(1-x) - EDTA.NH4

2(AlGa)-EDTA.NH4→ (AlGa)2O3+EDTAfragments 3(AlGa)2O3+6NH3→2(AlGa)3N3+9H2O

Dried in oven at 90 °C

AlXGa(1-x) - EDTA.NH4 placed inside reactor

AlGaN, GaN

At 400 °C liquid NH3

Powder X-ray Diffraction spectrum

900 °C for 8 hours

Scanning Electron Microscope image of GaN and AlGaN

(a)(a)GaN GaN (b) AlGaN (b) AlGaN

Schematic of Horizontal quartz tube reactor

(d)

Temperature (°C)

(a) GaN TEMPERATURE PROFILE

(b) AlGaN

Dwelling 8 hrs 900 °C

(c)

500 ºC N2

400 ºC NH3 14

Time (h)

22

Energy Dispersive X-ray spectrum

Photoluminescence spectrum

Conclusions  1 mole of Ga- EDTA complex yields 0.75 mole of gallium nitride product

 GaN powders are important because they can be used as source material for the sublimation growth of bulk GaN single crystal and wafer  AlGaN nanoparticles can be used in novel electronic devices and to study of quantum confinement effects, They can find possible application in quantum lasers and single electron transistor  XRD results confirms the wurtzite structure for both GaN and AlGaN  SEM image confirms that the morphology of GaN consist of microspheres and the AlGaN consist of microrods  EDX analysis confirms that no element other than Ga, Al and N were present in the sample and confirms the high purity of the samples  PL confirms the band edge emission at 376 nm for GaN and 345 nm for AlGaN  The Aluminum (Al) composition of 20% has been estimated from PL emission around 345 nm