Substrate rotation-induced composition modulation in epitaxial AlGaAs grown by molecular-beam epitaxy
Substrate rotation-induced composition modulation in epitaxial AlGaAs grown by molecular-beam epitaxy
复制标题
分子束外延生长的外延 AlGaAs 中衬底旋转引起的成分调制
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
A. Macrander
中科院分区：
文献类型：
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作者：
S. Chu;N. Chand;D. Sivco;A. Macrander
用横截面透射电子显微镜观察到了分子束外延生长的AlGaAs中Al摩尔分数沿生长方向的周期性变化。在AlGaAs中，这种成分调制的波长与生长过程中衬底的转速成反比，与生长温度无关。通过增加旋转速度以使调制周期合并成连续的成分来实现沿生长方向的均匀成分。半经验估计，在Al0.3Ga0.7As中，获得可见的周期对比度所需的Al摩尔分数的最小变化在Al0.3Ga0.7As中约为6%。在Al0.7Ga0.3As中没有观察到成分调制，这表明在高源温度下，整个晶片上的铝束通量分布的均匀性得到了改善。虽然霍尔测量和高分辨率x射线衍射仪显示生长的薄膜没有任何差异.
We observe a periodic variation of Al mole fraction along the growth direction in AlGaAs grown by molecular‐beam epitaxy on GaAs substrate by cross‐sectional transmission electron microscopy (TEM). The wavelength of such composition modulation in AlGaAs is inversely proportional to the substrate rotation speed during growth and is independent of the growth temperature used. Uniform composition along the growth direction is achieved by increasing the rotation speed such that the modulation period merges into a continuum composition. The minimum change in the Al mole fraction required to obtain a visible periodic contrast in the [200] dark‐field TEM images is estimated semiempirically to be about 6% in Al0.3Ga0.7As. Composition modulation was not observed in Al0.7Ga0.3As, indicating an improvement in the uniformity of the Al‐beam flux profile across the wafer at a high source temperature. Although Hall measurements and high‐resolution x‐ray diffractometry did not show any difference in layers grown with and...