Morphology of the Surface of modified AlN/Sapphire Substrates Obtained by Thermochemical Nitridation Method

Sapphire is the material most widely used in the capacity of substrates for technical devices based on the nitrides GaN, InN, AlN and  their solid solutions. However, the method of heteroepitaxy of the nitrides on sapphire substrates results in high dislocation density and other structure defects, due to discrepancy in the crystal lattice parameters and thermal expansion coefficients of these materials. This essentially complicates the obtaining of heterostructures with high functional characteristics. Since the commercial production of the substrates for homoepitaxial growth is expensive, much attention is being paid nowadays to the use of modified sapphire substrates with buffer nitride layers (GaN/sapphire or AlN/sapphire templates) which play the role of inherent nitride quasi-substrates. We have developed a new method for the obtaining of AlN/sapphire templates based on nitridation of sapphire in a gaseous mixture containing N2, СО, СО2, Н2, Н2О with low concentration of СО2 and Н2О.

This method allows to obtain polar AlN//Al2O3, AlN//Al2O3), semipolar (AlN// Al2O3) and nonpolar ( AlN// Al2O3) crystalline AlN layers on the surface of sapphire. Their thickness ranges between 20-30nm and several microns, the rocking curve half-width is less than 1º. In contrast to well-known deposition methods in which epitaxial films are obtained using external source, in the given method AlN layer is formed due to dissolution of nitrogen in anion-deficient corundum followed by crystal-chemical transformations in the surface-adjacent layer of sapphire substrate. Therefore, the nitride layer is to be formed after the stage of corundum reduction followed by etching of the substrate surface. The goal of the present work was to establish regularities of the influence of reducing annealing of sapphire substrate on the morphology of the surface of AlN/sapphire templates.


Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

• < Prev
• Next >