Fabrication of AlN Thin Film Substrates by 'Van Der Waals Lift-Off Technique'

摘要

The goal of the project was to develop a method to fabricate a free aluminumnitride (AlN) thin films. This was developed by growing AlN thin films on top of layered tungsten sulfide (WS2) thin films which were deposited on a mechanically rigid substrate material such as Si and Al2O3, followed by mechanical separation of AlN thin films thorough the inter-layers of WS2. This project involved the design and construction of a cold wall metal organic chemical vapor deposition (MOCVD) for WS2 thin films, and the AlN thin film deposition by atomic layer growth (ALG) process. WS2 thin films were deposited using the reaction of H2S with W(CO)6. Microstructure for WS2 thin films is generally characterized by the formation of crystallites with basal planes parallel to the interface for the first few tens of nanometers, followed by the formation of crystallites with their basal planes non-parallel to the substrate. Process conditions to grow AlN thin films via ALG using dimethylamine-alane (DMEAA) and ammonia (NH3) were investigated. Close proximity of the lattice constant of WS2 to those of AlN lead to a potential application of this materials as a substrate for subsequent growth of AlN, however, the lift-off process was severely dependent on the microstructure of WS2 interlayers.