High resolution XRD study of GaAs implanted with 50 MeV 120Sn ions
- 作者：Nair ; Geeta P. ; Chandrasekaran ; K.S. ; Narsale ; A.M. ; Arora ; B.M. ; Gokhale ; M.R.
- 关键词：61.72.V ; MeV ion implantation ; GaAs ; Sn ; High resolution XRD
- 刊名：Nuclear Instruments and Methods in Physics Research Section B ; Beam Interactions with Materials and Atoms
- 出版年：2001
- 期刊代码：42_0168583x
- 类别：ph
- 出版时间：December, 2001
- 卷：184
- 期：4
- 页码：515-522
- 文件大小：225 K
摘要
Semi-insulating (001) GaAs wafers implanted with 50 MeV 120Sn ions to a dose of 1014ions/cm2 have been studied in this work. Optical microscopy, in agreement with TRIM estimates, had indicated a depth of about 8.5 μm for the implanted layer. High resolution XRD profiles, with Bartels-type beam conditioner for CuKα1 X-rays of 12 arc second divergence in the scattering plane, were recorded for several Bragg reflections up to the highest scattering angles and analyzed. A considerable sample curvature and disorder scattering were noticed. Triple axes w/2θ scans show a sharp substrate peak while that of the implant region is broad showing considerable variation of d spacing. Simulations in the Takagi Taupin dynamical formalism, with a four-layer model of strain, mismatch, thickness and Debye–Waller factor for each layer, together with a convolution for sample curvature and random noise addition, yielded good fits to the recorded profiles. Independent experiments confirmed the curvature adopted in the simulation. Successive controlled etching, with XRD after each step, with simulations for appropriate thickness, justified the above model, with sharpened peaks and flattening of curvature with etching sequence. Another sample, with a higher dose of 5×1014ions/cm2 at the same energy, revealed essentially similar results for the layer damage and curvature but with enhanced mosaicity. A brief comparison with electrical and optical studies of similarly implanted samples is presented. Such studies indicated the presence of an amorphous layer. The present XRD work however suggests the layer to retain the crystalline nature in spite of a very high defect density.