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Updated on: July 15, 2010  
     
  GaN Thin Film  
 
 

Rough film showing hexagonal
symmetry

Introduction:
Scanning electron microscope image of a GaN thin film grown epitaxially by a method called chemical vapor deposition.

Overview:
The ability to synthesize materials in the form of thin films of the order of a few microns or less lies at the heart of the micro and nanoelectronics revolution that has taken place since the 1950's. However, thin film technology is not restricted to electronics alone. Among others, they are used to enable technologies that depend on the mechanical (e.g. wear resistant coatings), optical (e.g. anti-reflection glasses), magnetic (e.g. magnetic hard disks in computers) and thermal properties of materials. Thin films are deposited by a variety of techniques such as sputtering, pulsed layer deposition, chemical vapor deposition and molecular beam epitaxy. The synthesis and study of thin films of various materials is a very active area of research at the Materials research center and it is currently equipped with all the above synthesis methods listed.

Smooth film required for devices

Going Deeper:
GaN is a compound semiconductor and along with InN and AlN forms a class of materials that have enabled white and blue solid state lighting. Technology based on thin films of GaN such as these are used in the white LED (light emitting diode) flash lights and blue LEDs (seen in cell phones for example).

Just like the Au nanoplatelet and the Ga2O3 nanowires seen in the images before, the GaN films seen in the image to the left are also single crystals. The hexagonal features, upper image on the left, reflect the symmetry of arrangement of atoms within the material which is also hexagonal. Actual devices require thin films that are very smooth such as the one in the figure on the left below. Thus, the film in the upper image is actually a defective film. Part of Dr. Raghavan's research is centered around trying to understand how crystals grow and prevent such defects, with the ultimate aim of being able to use them in actual devices.

These images are from his post-doctoral work at The Pennsylvania State University with Dr. Joan Redwing. He plans to continue his work on crystal growth and growth of the Group III-A (Ga, In, Al) nitrides at MRC.

For more information on Dr. Raghavan's research visit his faculty page and homepage.

 
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