Control of Interfacial Gain Structure for Deposition of III-V Nitrides with RF Bias Atomic Layer Annealing

The low-temperature (<u>&lt;</u> 400 ^○C) deposition of polycrystalline AlN and GaN films on insulators such as SiO₂, SiN, and SiC is demonstrated by atomic layer annealing (ALA) using tris(dimethylamido) aluminum (TDMAA) or tris(dimethylamido) gallium (TDMAG) and anhydrous N₂H₄ with a rare gas plasma treatment utilizing a RF bias to tune the ion energy. ALA is a variant of ALD in which after the TDMAA/TDMAG and N₂H₄ are dosed, a pulse of low energy inert ions is used to bombard the growth surface to induce crystallinity in each ALD cycle. While on conducting substrates a simple DC bias can be employed, this is not effective or can result in dielectric breakdown on insulating substrates. In addition, for deposition of AlN, the DC bias is less efficient for thicker film growth. To overcome these issues, RF bias was employed which allows high quality polycrystalline AlN and GaN deposition on insulators at low temperature. Using TDMAA and N₂H₄+ Ar⁺ or Kr⁺ high-quality AlN films are deposited with large grain size and low oxygen/carbon contamination which can be used as a templating layer for further high speed AlN film growth via sputtering. While ALD of GaN has been reported in the literature, the most common deposition techniques are MOCVD and MBE at high temperatures &gt;700 ○C. Using ALA, the deposition of polycrystalline gallium nitride at a reduced temperature, 250 ^○C, was demonstrated<b>. </b>For optimal RF bias, the films displayed strong (002) crystallinity, an average crystallite size of 11.4 nm, and near bulk density. Application for low temperature AlN ALA deposition on insulators include templating of AlN heat spreaders