| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | Matthew Kane, Texas A&M University |
| Authors: | N. Arefin, University of Oklahoma P. Larson, University of Oklahoma M.H. Kane, Texas A&M University M.B. Johnson, University of Oklahoma P.J. McCann, University of Oklahoma |
| Correspondent: | Click to Email |
This poster will describe results recently obtained with pulsed electron beam deposition (PED) of AlN on sapphire and silicon substrates. The PED technique is potentially useful for growth of III-nitrides at lower substrate temperatures, a capability that can allow use of new buffer layer materials, integration of chemically dissimilar materials, and help solve wafer bowing issues. In addition, PED has the advantage to deposit materials that are transparent to the Kr-F excimer lasers used in pulsed laser deposition and would thus be suitable for ultra-wide bandgap materials. Systematic studies are needed to explore the growth regimes for various materials as a function of processing conditions and sample preparation techniques. AlN was deposited on sapphire and silicon (111) at a substrate temperature of 500°C and 550°C, respectively, in a UHP N2 (15 mTorr) environment (without any surface pre-treatment, i.e., pre-nitridation). A high power electron gun pulse was used to ablate the AlN target (1” dia. x 0.250” thick, 99.8% pure) stationed at 5 cm vertical distance from the substrate. The electron pulses were generated at 15KV, 0.3 J/pulse at 1 Hz for one hour. No post growth processing was performed following the growth. Scanning electron microscopy (SEM), Electron back scattered diffraction (EBSD), and X-ray diffraction (XRD), and various optical characterization techniques were performed on the as-grown material. SEM imaging confirms hexagonal faceted high aspect ratio AlN nanowires on both sapphire and silicon substrates. The nanowire lengths ranged from 10-100 µm with average diameter of 2.5 µm on the sapphire substrate, while on the silicon (111) substrate the nanowire dimensions ranged from 200 nm–10 µm in length, and the average diameter was 0.5 µm. EBSD scan over the nanowires identified the structures as c-plane oriented AlN. XRD θ–2θ scans from 2θ = 30° to 2θ = 50° showed only one peak other than those from the sapphire substrate, at 2θ = 37.56°. We had insignificant contribution from the AlN NWs in the XRD scan due to limited quantity of the NWs on the sample. The obtained peak at 2θ = 37.56° represents Al (111) suggests that during the initial growth phases Al was accumulated as metal on the substrate which acted as a precursor in initiating the nanowire growth afterwards. This finding was also verified with EBSD scans, as it also detected presence of Al crystallites on the sample surface as well as highly c-axis oriented AlN nanowires.