Mn configuration in III‐V semiconductors and its influence on electric transport and semiconductor magnetism
Mn configuration in III‐V semiconductors and its influence on electric transport and semiconductor magnetism
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DOI：
10.1002/pssc.200982521
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发表时间：
2009-12
期刊：
影响因子：
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通讯作者：
A. Wołoś;M. Piersa;G. Strzelecka;K. Korona;A. Hruban;M. Kamińska
中科院分区：
文献类型：
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作者：
A. Wołoś;M. Piersa;G. Strzelecka;K. Korona;A. Hruban;M. Kamińska
研究了不同掺杂浓度范围内的GaP和GaP，并与InP和氮化物、GaN和AlN的文献数据进行了比较，以了解其中一些材料的铁磁性机制。中等浓度的Mn掺杂使这些化合物具有相似的电输运特性，即高温下以与Mn受主电离能相关的能量激活的主晶价带的p型电导和低温下以Mn杂质带的跳跃电导为主的电导。从跃迁电导的大小可以确定，在宽带隙氮化物、GaN和AlN中，由于不同的局域半径从GaAs到InP到GaP依次递减，并实现了完全局域化，因此可以确定Mn的组态为Mn2+(D5)，在其上有一个束缚空穴。与Mn空穴波函数完全重叠有关的金属-绝缘体转变的临界Mn浓度分别为：在GaP中为3.6×1020 cm-3，在InP中为2.5×1021 cm-3，在GaP中为3.7×1022 cm-3，后者相当于100at.%以上。与GaP类似，掺Mn的GaN和AlN也不能实现金属-绝缘体转变，即使在100%的Mn浓度下也是如此。在掺锰约2.8×1019 cm-3的GaAs中，形成了分裂的Mn杂质带。在此Mn浓度下，能带的电导具有高迁移率的特点，在大小上可与GaAs价带的迁移率相媲美。高Mn含量(~gt；1.1-1.6at.%)的GaAs铁磁性发生在金属-绝缘体转变的金属侧，这意味着在Mn中心的铁磁有序中的中介中心是完全非定域空穴。这一机制在其他所研究的III-V化合物中是难以实现的，因为锰结合空穴的局域化程度较高。(2019Wiley-VCH Verlag GmbH&Co.KGaA，Weinheim)
GaAs and GaP doped with Mn at wide range of concentrations were studied and compared to literature data of InP and nitrides, GaN and AlN, in aim to understand the mechanism of ferromagnetism observed in some of them. Doping with a moderate Mn concentrations resulted in similar features of electric transport in these compounds, that is p-type conductivity in host crystal valence band activated with energy related to the ionization energy of Mn acceptor at high temperature and hopping conductance in Mn impurity band dominating at low temperatures. From the magnitude of hopping conductance it was possible to determine Mn configuration, which occurred to be Mn2+(d5) with a bound hole on it, with different localization radius decreasing systematically in a series from GaAs through InP down to GaP and achieving full localization resulting in Mn3+(d4) configuration in wide band gap nitrides, GaN and AlN. A critical concentration of Mn for metal-insulator transition related to full overlap of Mn-bound hole wave functions could be calculated as equal to 3.6 × 1020 cm–3 in GaAs, 2.5 × 1021 cm–3 in InP and 3.7 × 1022 cm–3 in GaP, where the latter one corresponds to above 100 at.%. Similarly to GaP, metal-insulator transition for GaN and AlN doped with Mn cannot be achieved even for 100% of Mn concentration. In GaAs doped with Mn on the level of about 2.8 × 1019 cm–3 split Mn impurity band is formed. Conductivity in the band at this Mn concentration is characterized by high mobility, comparable in magnitude to the mobility in GaAs valence band. Ferromagnetism of GaAs with high Mn concentration (> 1.1 - 1.6 at.%) occurs in samples being on the metallic side of metal-insulator transition what means that a mediating center in ferromagnetic ordering of Mn centers is totally unlocalized hole. This mechanism is difficult to realize in other studied III-V compounds because of higher localization of Mn-bound holes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)