Layer-by-Layer Growth of GaN on Sapphire by Low Temperature Cyclic Pulsed Laser Deposition / Nitrogen RF Plasma

Abstract

AbstractRecently we have proposed a new layer-by-layer method for deposition of group-III nitrides from elemental precursors (Ga, N2) [1,2]. This technique is based on a two-step cyclic process, which alternates Pulsed Laser Deposition (PLD), of a liquid gallium target and nitrogen plasma treatment. In this work, we proceed on the development of this flexible cyclic deposition technique and study the influence of the power and time duration of the 1 mbar nitrogen RF plasma on the GaN thin films. The layers are deposited on pre-nitridated sapphire (0001) substrates at low deposition temperature (600° C) to minimise reevaporation. The cyclic GaN thin films thus obtained are compared in terms of crystal alignment and nitrogen incorporation. X-ray diffraction and optical transmission spectra are the selected tools used to characterise and compare the deposited films.