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Studies on Heteroepitaxial Growth of III-V Diluted Magnetic Semiconductors on Si Substrates

Si衬底上III-V族稀磁半导体异质外延生长研究

基本信息

批准号：
14550005
负责人：
UCHITOMI Naotaka
金额：
$ 2.37万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

The III-V-based diluted magnetic semiconductor (Ga,Mn) As is one of the most promising materials for potential use in spintronic devices. (Ga,Mn) As is usually grown on GaAs substrates using low temperature molecular beam epitaxy (MBE), and has been combined with 4-6% Mn ions for metallic-phase ferromagnetism.We investigated the growth of diluted magnetic semiconductor (DMS) (Ga_<1_x>, Mn_x) As epitaxial layers on n-type Si(100) substrates using low-temperature-molecular beam epitaxy (LT-MBE). The Mn content of the (Ga_<1_x>, Mn_x) As layers was relatively high (6.2%). The ferromagnetic transition temperature Tc was estimated to be 80 K for the as-grown film, and it strongly depended on the annealing temperature. The p-(Ga, Mn) As/n-Si heterostructures showing a ferromagnetic nature indicated a change in the sign of the Hall coefficient. We found that the transition temperature from n-type to p-type conduction considerably correlates with the Tc. We also studied the properties and annealing effects of substrate-free (Ga,Mn) As films prepared by etching Si substrates from (Ga,Mn) As/Si structures, and compared the results with those from (Ga,Mn) As/Si heterostructures. The substrate-free (Ga,Mn) As films with 6% Mn content were annealed at 250 degree C as a function of time. From Hall-effect measurements, the Curie temperature of substrate-free (Ga,Mn) As films was estimated to be 87 K for an as-grown film, enhanced up to 152 K after low temperature annealing for 60 min. We found that the (Ga,Mn) As films grown on Si substrates show a relatively high Curie temperature.

III-V基稀磁半导体(Ga，Mn)As是最有潜力用于自旋电子器件的材料之一。利用低温分子束外延技术(LT-MBE)在n型Si(100)衬底上生长了稀磁半导体(DMS)(Ga&lt；1x&Gt；，Mnx)As外延层。(Ga&lt；1x&Gt；，Mnx)As层的Mn含量较高(6.2%)。测得薄膜的铁磁转变温度T_c为80K，它强烈地依赖于退火温度。具有铁磁性的p-(Ga，Mn)As/n-Si异质结显示出霍尔系数的符号变化。我们发现，从n型导电到p型导电的转变温度与T_c密切相关。我们还研究了用(Ga，Mn)As/Si结构刻蚀Si衬底制备的无衬底(Ga，Mn)As薄膜的性能和退火热效应，并与(Ga，Mn)As/Si异质结的结果进行了比较。对含6%Mn的无衬底(Ga，Mn)As薄膜在250℃下进行了随时间变化的退火处理。根据霍尔效应测量，无衬底(Ga，Mn)As薄膜的居里温度估计为87K，低温热处理60min后居里温度提高到152K。我们发现在硅衬底上生长的(Ga，Mn)As薄膜具有较高的居里温度。