Structural characterization of AlN films synthesized by pulsed laser deposition |
| |
Authors: | A SzekeresZs Fogarassy P PetrikE Vlaikova A CzirakiG Socol C RistoscuS Grigorescu IN Mihailescu |
| |
Institution: | a Institute of Solid State Physics, Bulgarian Academy of Sciences, 72, Tzarigradsko Chaussee blvd., 1784 Sofia, Bulgaria b Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Konkoly Thege Miklos u. 29-33, H-1121 Budapest, Hungary c Eotvos Lorand University, 1 Pazmany Peter setany, 1117 Budapest, Hungary d National Institute for Lasers, Plasma, and Radiation Physics, PO Box MG-54, RO-77125 Magurele, Ilfov, Romania |
| |
Abstract: | We obtained AlN thin films by pulsed laser deposition (PLD) from a polycrystalline AlN target using a pulsed KrF* excimer laser source (248 nm, 25 ns, intensity of ∼4 × 108 W/cm2, repetition rate 3 Hz, 10 J/cm2 laser fluence). The target-Si substrate distance was 5 cm. Films were grown either in vacuum (10−4 Pa residual pressure) or in nitrogen at a dynamic pressure of 0.1 and 10 Pa, using a total of 20,000 subsequent pulses. The films structure was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and spectral ellipsometry (SE). Our TEM and XRD studies showed a strong dependence of the film structure on the nitrogen content in the ambient gas. The films deposited in vacuum exhibited a high quality polycrystalline structure with a hexagonal phase. The crystallite growth proceeds along the c-axis, perpendicular to the substrate surface, resulting in a columnar and strongly textured structure. The films grown at low nitrogen pressure (0.1 Pa) were amorphous as seen by TEM and XRD, but SE data analysis revealed ∼1.7 vol.% crystallites embedded in the amorphous AlN matrix. Increasing the nitrogen pressure to 10 Pa promotes the formation of cubic (≤10 nm) crystallites as seen by TEM but their density was still low to be detected by XRD. SE data analysis confirmed the results obtained from the TEM and XRD observations. |
| |
Keywords: | Polycrystalline Aln thin films Structural investigations Pulsed laser deposition |
本文献已被 ScienceDirect 等数据库收录! |
|