Real-time synchrotron x-ray studies of low- and high-temperature nitridation of c-plane sapphire
Real-time synchrotron x-ray studies of low- and high-temperature nitridation of c-plane sapphire
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c 面蓝宝石低温和高温氮化的实时同步加速器 X 射线研究
DOI：
10.1103/physrevb.74.235304
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发表时间：
2006
影响因子：
3.7
通讯作者：
D. Siddons
中科院分区：
文献类型：
--
作者：
Yiyi Wang;A. S. Özcan;Gözde Özaydin;K. Ludwig;A. Bhattacharyya;T. Moustakas;Hua Zhou;R. Headrick;D. Siddons
使用掠入射实时x射线衍射、原位x射线反射和原位反射检查了c面蓝宝石在低（200-300 {sup o}C）和高（750 {sup o}C）衬底温度下的等离子体氮化动力学。高能电子衍射（RHEED）。这些监测氮化过程中的氮化物的厚度，应变和表面结构的演变。AlN（101{bar 0}）峰的演变表明，第一氮化物层中的异质外延应变相对于衬底已经显著弛豫。随后的层随着增加的弛豫而生长。在高温和低温氮化的情况下，结果表明，早期阶段的氮化是由一个复杂的成核和生长过程。在这两个温度下的氮化显然是在一个二维的生长模式与初始成核岛由几个单层横向生长。在低温下，在覆盖表面的成核岛的撞击之后，生长减慢或甚至停止，这可能是由于通过现有层的低扩散率。在高温下的成核岛的初始形成和生长速率与在低温下的成核岛的初始形成和生长速率相当，但随后生长到衬底中的成核岛在低温情况下显著增强，与0.1-0.25 eV的活化能一致。
The plasma nitridation kinetics of c-plane sapphire at both low (200-300 {sup o}C) and high (750 {sup o}C) substrate temperatures was examined using grazing-incidence real-time x-ray diffraction, in situ x-ray reflection and in situ reflection high-energy electron diffraction (RHEED). These monitored the evolution of the nitride thickness, strain, and surface structure during nitridation. The evolution of the AlN(101{bar 0}) peak showed that the heteroepitaxial strain in the first layer of nitride is already significantly relaxed relative to the substrate. Subsequent layers grow with increasing relaxation. In both the high- and low-temperature nitridation cases, the results suggest that the early stage nitridation is governed by a complex nucleation and growth process. Nitridation at both temperatures apparently proceeds in a two-dimensional growth mode with the initial nucleating islands consisting of several monolayers which grow laterally. At low temperature the growth slows or even stops after impingement of the nucleating islands covering the surface, possibly due to low diffusivities through the existing layer. Initial formation and growth rates of nucleating islands at high temperatures are comparable to those at low temperatures, but subsequent growth into the substrate is significantly enhanced over the low temperature case, consistent with activation energies of 0.1-0.25 eV.