Sancho-Juan O, Cantarero A, Garro N, Cros A, Martínez-Criado G, Salomé M, Susini J, Olguín D, Dhar S
Materials Science Institute, University of Valencia, PO Box 22085, E46071 Valencia, Spain.
J Phys Condens Matter. 2009 Jul 22;21(29):295801. doi: 10.1088/0953-8984/21/29/295801. Epub 2009 Jul 3.
By means of x-ray absorption near-edge structure (XANES) several Ga(1-x)Mn(x)N (0.03<x<0.09) layers have been analyzed. The Mn-doped GaN samples consisted of different epilayers grown by molecular beam epitaxy on [0001] SiC substrates. The low mismatch between GaN and SiC allows for a good quality and homogeneity of the material. The measurements were performed in fluorescence mode around both the Ga and Mn K edges. All samples studied present a similar Mn ionization state, very close to 2+, and tetrahedral coordination. In order to interpret the near-edge structure, we have performed ab initio calculations using the full potential linear augmented plane wave method as implemented in the Wien2k code. The calculations show the appearance of a Mn bonding [Formula: see text] band localized in the gap region, and the corresponding anti-bonding state [Formula: see text], which seem to be responsible for the double structure which appears at the pre-edge absorption region. The shoulders and main absorption peak of the XANES spectra are attributed to transitions from the Mn(1s) band to the conduction bands, which are partially dipole allowed because of the Mn(4p) contribution to these bands.
借助X射线吸收近边结构（XANES）分析了几个Ga(1-x)Mn(x)N（0.03<x<0.09）层。掺锰的氮化镓样品由通过分子束外延生长在[0001]碳化硅衬底上的不同外延层组成。氮化镓和碳化硅之间的低失配使得材料具有良好的质量和均匀性。测量是在围绕镓和锰的K边的荧光模式下进行的。所有研究的样品都呈现出相似的锰离子化状态，非常接近2+，并且具有四面体配位。为了解释近边结构，我们使用Wien2k代码中实现的全势线性缀加平面波方法进行了从头算计算。计算结果显示在能隙区域出现了一个局域化的锰成键[公式：见原文]带，以及相应的反键态[公式：见原文]，它们似乎是导致在前边吸收区域出现双重结构的原因。XANES光谱的肩部和主要吸收峰归因于从锰（1s）带向导带的跃迁，由于锰（4p）对这些能带的贡献，这些跃迁部分地允许偶极跃迁。
