Structural and Optical Properties of Aluminum Nitride Thin Films Deposited by Pulsed DC Magnetron Sputtering

R K Choudhary,P Mishra,A C Bidaye,A Biswas

doi:10.1155/2013/759462

Abstract

Aluminum nitride thin films were deposited on Si (100) substrate by pulsed DC (asymmetric bipolar) reactive magnetron sputtering under variable nitrogen flow in a gas mixture of argon and nitrogen. The deposited film was characterized by grazing incidence X-ray diffraction (GIXRD), atomic force microscope (AFM), spectroscopic ellipsometry, and secondary ion mass spectroscopy (SIMS). GIXRD results have shown (100) reflection of wurtzite AlN, whereas AFM micrographs have revealed very fine grained microstructure with average roughness in the range 6–8 nm. Spectroscopic ellipsometry measurements have indicated the band gap and refractive index of the film in the range 5.0–5.48 eV and 1.58–1.84, respectively. SIMS measurement has indicated the presence of oxygen in the film.

Highlights

Aluminum nitride, a III-V family compound, has excellent combination of physical, chemical, and mechanical properties
AlN films/coatings have been grown by several methods which include pulsed laser deposition [2], reactive molecular beam epitaxy [3], vacuum arc/cathodic arc deposition [4], DC/RF reactive sputtering [5,6,7], ion beam sputtering [8], metal-organic chemical vapor deposition (MOCVD) [9], and miscellaneous [10] other techniques
Properties of AlN films depend upon the crystal structure, crystal orientation, microstructure, and chemical composition, which in turn depend upon the deposition conditions such as sputtering power, pulse frequency, duty cycle, growth temperature, nitrogen/argon flow ratio, and sputtering gas pressure

Summary

Introduction

A III-V family compound, has excellent combination of physical, chemical, and mechanical properties. Properties of AlN films depend upon the crystal structure, crystal orientation, microstructure, and chemical composition, which in turn depend upon the deposition conditions such as sputtering power, pulse frequency, duty cycle, growth temperature, nitrogen/argon flow ratio, and sputtering gas pressure. Effect of nitrogen/argon flow ratio on the optical properties of AlN films have been widely reported for DC and RF magnetron sputtering [5, 6, 13], but the same has not been studied in detail for pulsed DC magnetron sputtering. In this study, we have deposited aluminum nitride thin films by pulsed DC reactive magnetron sputtering for a wide range of nitrogen/argon flow ratio and their effect on optical properties has been studied using the spectroscopic ellipsometry technique. In the same work, study on structure and morphology of the film has been conducted using GIXRD and AFM

Experimental Methods

Results and Discussion

Conclusions