(Invited) Atomic Layer Deposition as the Enabler for the Meta Stable Semiconductor InN and Its Alloys

Abstract

Indium nitride (InN) is highly interesting for high-frequency and high-speed electronics given the remarkably high electron mobility in InN. The development of InN based electronics is hampered by the difficulty in depositing high quality thin films. The InN crystal breaks down to indium metal and nitrogen gas at about 500 °C which limits the deposition temperature, making conventional chemical vapor deposition (CVD) poorly suited for InN. Atomic Layer Deposition (ALD) is a low temperature, time-resolved form of CVD where the precursor gases are pulsed sequentially, separated by inert gas. This renders a deposition chemistry fully controlled by surface chemistry. We hypothesized around 2015 that the surface-controlled deposition of ALD will be beneficial for InN deposition and started our activities on ALD of InN.I will describe our work on ALD of InN films where we have focused on ALD process development and design of new precursors. We now can show that ALD is an enabling technology for InN based electronics as it is capable of depositing a few nanometers continuous, epitaxial InN films.[1] I will describe our results on epitaxial growth of InN by ALD using our newly invented In precursor [2] and describe why we believe that the key to the success of ALD for InN is the dynamic gas exchange during the deposition.[3] I will also show our atomic scale understanding of the growth chemistry from quantum chemical modelling,[4] and how the results can be extended to InxGa1-xN.[5, 6]