AlN:Cr thin films synthesized by pulsed laser deposition: Studies by X-ray diffraction and spectroscopic ellipsometry

被引:15
作者
Szekeres, A. [2 ]
Bakalova, S. [2 ]
Grigorescu, S. [1 ]
Cziraki, A. [3 ]
Socol, G. [1 ]
Ristoscu, C. [1 ]
Mihailescu, I. N. [1 ]
机构
[1] Natl Inst Lasers Plasma & Radiat Phys, RO-77125 Bucharest, Magurele, Romania
[2] Bulgarian Acad Sci, Inst Solid State Phys, BU-1784 Sofia, Bulgaria
[3] Eotvos Lorand Univ, Fac Solid State Phys, H-1117 Budapest, Hungary
关键词
Cr-doped AlN films; Spectroscopic ellipsometry; Compressive stress in PLD films; Optical characteristics of AlN films; ALUMINUM NITRIDE; GROWTH;
D O I
10.1016/j.apsusc.2008.08.104
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The structure and optical properties of AlN thin films doped with Cr atoms were studied by X-ray diffractometry, Fourier transform infrared spectroscopy and spectroscopic ellipsometry analyses. The films were synthesized by pulsed laser deposition from an AlN: Cr (10% Cr) target onto Si(1 0 0) wafers in vacuum at residual pressure of 10 (-3) Pa or in nitrogen at a dynamic pressure of 0.1 Pa. The study of the XRD patterns revealed that both phases co-existed in the synthesized films and that the amorphous one was prevalent. Two different amorphous matrices, i.e. two types of chemical bond arrangements, were found in films deposited at 0.1 Pa N-2. By difference, deposition in vacuum resulted in the coexistence of hexagonal and cubic crystallites embedded into an amorphous matrix. The introduction of Cr atoms into the AlN lattice causes a broadening of the IR spectrum along with the shift toward higher wavenumbers of the characteristic Al-N bands at 2351 cm (-1) and 665 cm (-1), respectively. This was related to the generation of a compressive stress inside films. In comparison to the optical constants of pure AlN films, the synthesized AlN: Cr films exhibited a smaller refractive index and showed a weak absorption throughout the 300-800 nm spectral region, characteristic to amorphous AlN structure. (C) 2008 Elsevier B. V. All rights reserved.
引用
收藏
页码:5271 / 5274
页数:4
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