Crystalline Gallium Nitride Deposition by RF-Biased Atomic Layer Annealing

A method has been developed for depositing polycrystalline gallium nitride (GaN) thin films at low temperature (400 °C) with potential applications in the RF and microLED industries. [1] There is a need to deposit GaN directly on common substrates such as silicon, SiO 2 , and SiN to reduce the cost associated with using SiC wafers, especially for chiplet stacking or 2.5D integration. While ALD of GaN has been reported in the literature, the most common deposition techniques are MOCVD and MBE at high temperatures >700 °C. [1] , [2] The difference in high deposition temperature and low operating temperature often results in strained material with significant defect densities. [1] Herein we demonstrate the deposition of polycrystalline gallium nitride at a reduced temperature, 400 °C, using tris(dimethylamido)gallium (TDMAGa) and anhydrous hydrazine in an atomic layer annealing (ALA) process. It is possible that by depositing a GaN templating layer by ALA at low temperature may reduce inherent strain in the material and buffer layer thickness required to form device-quality GaN using further deposition by other techniques.