[12p-A501-1~16] 10.4 半導体スピントロニクス・超伝導・強相関

▼ [12p-A501-3] Carrier type switching in quaternary alloy ferromagnetic semiconductor (In,Ga,Fe)Sb
by controlling the composition of In and Ga

〇Tomoki Hotta¹、Kengo Takase¹、Kosuke Takiguchi¹、Suriharsha Karumuri¹、Anh Le Duc^1,2、Masaaki Tanaka^1,3 (1.Univ. of Tokyo、2.IEI, Univ. of Tokyo、3.CSRN)

キーワード：ferromagnetic semiconductor, high Curie temperature, spintronics

Ferromagnetic semiconductors (FMSs) are promising materials for low-power spin-based devices because they show both the properties of ferromagnets and semiconductors. Recently, we have successfully grown both p-type and n-type Fe-doped III-V FMSs with high Curie temperature (T_C); p-type (Ga,Fe)Sb with T_C = 400 K and n-type (In,Fe)Sb with T_C = 385 K by low-temperature molecular-beam epitaxy (LT-MBE). With alloying p-type (Ga,Fe)Sb and n-type (In,Fe)Sb, we may be able to switch the carrier type with only a slight change of the lattice constant and band structure while maintaining high T_C, which will be useful for understanding the origin of the carrier type and ferromagnetism in the Fe-doped FMSs. In this work, we have grown both p-type and n-type (In_1-x-y,Ga_x,Fe_y)Sb thin films with room-temperature ferromagnetism. We grew heterostructures consisting of (from top to bottom) InSb (2 nm) / (In_1-x-y,Ga_x,Fe_y)Sb (15 nm, x = 2, 4, 6, 8, 10 %, y = 16 %) / AlSb (100 nm) / AlAs (6 nm) / GaAs (100 nm) on a semi-insulating GaAs(001) substrate by LT-MBE. From the linear slope of the R_Hall – magnetic field (H) at high H (> 10000 Oe), the carrier type of (In_1-x-y,Ga_x,Fe_y)Sb is found to be switched from p-type to n-type by decreasing x from 10 % to 6 %. This trend is consistent with the previous result; (In,Fe)Sb is n-type and (Ga,Fe)Sb is p-type. The carrier type of (In_1-x-y,Ga_x,Fe_y)Sb can be changed between p-type and n-type with a slight change of the lattice constant and band structure.