Effect of Be doping on the properties of GaMnAs ferromagnetic semiconductors
Effect of Be doping on the properties of GaMnAs ferromagnetic semiconductors
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DOI：
10.1063/1.1556272
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发表时间：
2003-05-15
影响因子：
3.2
通讯作者：
Furdyna, JK
中科院分区：
文献类型：
--
作者：
Lee, S;Chung, SJ;Furdyna, JK
我们研究了两种不同Be掺杂水平的Ga1-xMnxAs分子束外延膜。本研究选择了两个Mn浓度x: 0.03和0.05，并在每个系列中保持恒定。这些样品通过SQUID和磁输运测量进行了表征。在x=0.03的Ga1-xMnxAs系列的SQUID测量中，观察到居里温度T-C有系统的升高。在零磁场下测量的电阻率在居里温度附近出现局部最大值，反映了临界散射在T-C附近的影响。在这个低x范围内，Ga1-xMnxAs中观察到的T-C的增加可以解释为由于be掺杂引起的体系中自由载流子浓度的增加。然而，在Mn浓度较高的Ga1-xMnxAs系列中（x=0.05），测量结果显示，随着Be掺杂水平的增加，T-C有系统地降低。我们从载流子浓度的基本限制方面讨论了这种效应，载流子浓度可以由Ga1-xMnxAs涂层进行热力学调节。(C) 2003年美国物理研究所。
We have studied two series of molecular beam epitaxy grown Ga1-xMnxAs epilayers with several different Be doping levels. Two Mn concentrations x were chosen for this study: 0.03 and 0.05, and these values were maintained constant in each series. These samples were characterized by using SQUID and magnetotransport measurements. A systematic increase of the Curie temperature T-C was observed in SQUID measurements on the series of Ga1-xMnxAs with x=0.03. The resistivity measured at zero magnetic field shows a local maximum near the Curie temperature, reflecting the effects of critical scattering near T-C. The observed increase of T-C in Ga1-xMnxAs for this low range of x can be explained by the increase of the free carrier concentrations in the system arising from Be doping. However, in the series of Ga1-xMnxAs with the higher concentration of Mn (x=0.05), the measurements reveal that the T-C systematically decreases with increasing Be doping level. We discuss this effect in terms of a fundamental limitation of the carrier concentration that can be thermodynamically accommodated by Ga1-xMnxAs epilayers. (C) 2003 American Institute of Physics.