Proceedings Article | 10 September 2019
KEYWORDS: Ferromagnetics, Group III-V semiconductors, P-type semiconductors, Semiconductors, Heterojunctions, Spintronics, Iron, Chemical species, Molecular beam epitaxy, Thin film growth
Ferromagnetic semiconductors (FMSs) with high Curie temperature (TC) are highly required for spintronics device applications. So far, however, the mainly studied FMSs, Mn-doped III-V FMSs, are only p-type and their TC values were much lower than 300 K. To search for new FMSs with high TC, most efforts have been concentrated on wide-gap materials [1], which yields no reliable and systematic result.
We present a new class of FMSs with high TC, Fe-doped narrow-gap III-V FMSs. Because Fe atoms replace the cation (group-III) sites in the isoelectronic Fe3+ state, the carrier type can be controlled independently and thus both n-type and p-type FMSs are obtained. Using low-temperature molecular beam epitaxy, we have successfully grown zinc-blende-type thin-film crystals of both p-type FMSs [(Ga,Fe)Sb [2], (Al,Fe)Sb [3]] and n-type FMSs [(In,Fe)As [4], (In,Fe)Sb [5]]. The most notable feature in these Fe-based FMSs is that the TC value increases monotonically as the Fe content increases; and there is a tendency that TC is higher as the bandgap is narrower, which contradicts the prediction of the conventional mean-field Zener model. Intrinsic room-temperature ferromagnetism has been observed in (Ga1-x,Fex)Sb with x > 23% [2] and (In1-x,Fex)Sb with x > 16% [5]. These findings indicate that the Fe-doped III-V FMSs are promising for spintronics devices operating at room temperature.
References
[1] T. Dielt et al., Phys. Rev. B 63, 195205 (2001).
[2] N. T. Tu et al., Appl. Phys. Lett. 108, 192401 (2016) [Featured Article].
[3] L. D. Anh et al., Appl. Phys. Let 107, 232405 (2015).
[4] P. N. Hai et al., Appl. Phys. Lett. 101, 182403 (2012).
[5] N. T. Tu et al., APEX 11 (6), 063005 (2018).
