Crystal AlN deposited at low temperature by magnetic field enhanced plasma assisted atomic layer deposition

Abstract

In this paper, AlN films prepared at low temperature by magnetic field enhanced plasma assisted atomic layer deposition (PA-ALD) using trimethyl aluminum and the mixture gas of nitrogen and hydrogen were investigated. Two discharge modes were employed for PA-ALD AlN, i.e., radio-frequency (RF) discharge mode and microwave electron cyclotron resonance (ECR) mode. The structure of the film, compositions, crystallinity, surface roughness, and properties of refractive index as well as photoluminescence were studied by Fourier transform infrared spectroscope, x-ray photoelectron spectroscope, x-ray diffraction, atomic force microscope, spectroscopic ellipsometry, and photoluminescence spectrometer, respectively. Comparison of the as-deposited films prepared in two discharge modes, the authors result that temperature played an important role in in ECR mode, AlN films deposited in ECR mode at 250 °C is crystalline except a little bit of aluminum rich with the contamination of carbon and oxygen; whereas in RF discharge mode, the direct interaction of plasma, the all process parameters affect the properties of the AlN films, like the strength of magnetic field, deposition temperature. The intense emission band measured through photoluminescence spectrum of the as-deposited AlN suggests that there may be potential applications in electronic and optoelectronic nanodevices.