- Nano Express
- Open Access
Observation of linear and quadratic magnetic field-dependence of magneto-photocurrents in InAs/GaSb superlattice
© Li et al.; licensee Springer. 2014
- Received: 24 March 2014
- Accepted: 5 May 2014
- Published: 31 May 2014
We experimentally studied the magneto-photocurrents generated by direct interband transition in InAs/GaSb type II superlattice. By varying the magnetic field direction, we observed that an in-plane magnetic field induces a photocurrent linearly proportional to the magnetic field; however, a magnetic field tilted to the sample plane induces a photocurrent presenting quadratic magnetic field dependence. The magneto-photocurrents in both conditions are insensitive to the polarization state of the incident light. Theoretical models involving excitation, relaxation and Hall effect are utilized to explain the experimental results.
- Asymmetric excitation and relaxation
- Spin-orbit interaction
MPE has been observed in InGaAs/InAlAs two-dimensional electron gas, GaAs/AlGaAs quantum well, graphene and so on [5–7]. By comparison, the InAs/GaSb type II supperlattice has some advantages in investigating spin transport and fabricating spintronic devices for its properties of large SOI in InAs and GaSb, relatively high carrier mobility in InAs and peculiar energy band structure [8, 9]. Previously, the InAs/GaSb type II superlattice has been extensively researched as an infrared detector. The studies have been mainly focused on carrier recombination, interface properties, tailoring of energy bands and so on [10–17]. The zero-field spin splitting has also been observed in InAs/GaSb quantum wells by Shubnikov-de-Haas oscillation , while the investigations on the magneto-photo effect is seldom concerned. In the present paper, we investigate the MPE in the InAs/GaSb type II supperlattice. Unlike the previous researches of the magnetic field strength dependence of the photocurrents, we mainly focus on the magnetic field direction dependence of the photocurrents in this structure. By varying magnetic field direction in or out of the sample plane, we observed linear and quadratic magnetic field dependence of the photocurrents, respectively. More information about excitation and relaxation of electrons in this structure were obtained from the experiments.
The InAs/GaSb superlattice was fabricated by molecular beam epitaxy technique on semi-insulating (001)-oriented GaAs substrate. The 500-nm GaAs and 1,000-nm GaSb buffers were deposited on the substrate to relieve the lattice mismatch. Then an InAs/GaSb superlattice of 155 periods was deposited. The monolayer thicknesses of InAs and GaSb are 3.85 and 2.60 nm, respectively. The sample was not intentionally doped. The energy gap of this structure calculated by the k ·p theory is 129.5 meV. The standard Hall measurement demonstrates that the sample is n-type at room temperature, i.e. electrons are the main carriers contributing to transport. Since in the n-type superlattice spin relaxation time and lifetime of holes are much shorter than those of electrons, we neglect the contribution of holes to the magneto-photocurrents. Four pairs of ohmic contact electrodes which are parallel to , ,  and  crystallographic directions were equidistantly made on the edges.
The experimental setup is shown in Figure 1b. A linearly polarized 1,064-nm laser normally irradiated on the center of the sample to excite direct interband transition of electrons. Hence, the circular photogalvanic effect and linear photogalvanic effect  are forbidden in this C 2v symmetry structure for the normal incidence case. A permanent magnet was used to generate magnetic field which can be along arbitrary direction in the sample plane. The investigation of photogalvanic effect was carried out at room temperature by rotating the magnetic field. The data were collected by a standard lock-in amplification technique. Specifically, the laser power was about 63 mW, the light spot diameter was 1.2 mm and the permanent magnet strength was 0.1 T. Besides, we choose x, y and z to be along ,  and  crystallographic directions, respectively.
In-plane magnetic field-dependent MPE
By extracting the peak-to-peak values of the currents (Jpp) in four crystallographic directions, we observed that Jpp in the  and  crystallographic directions are larger than that in the  and  directions. Merely considering the SOI-induced anisotropic splitting of the energy bands (see ) seems unable to explain this experimental result. Actually, the total photocurrents(described by Jpp) are decided by both SOI and Zeeman splitting. The SOI generates the spin-dependent asymmetric transition matrix elements and scattering matrix elements in excitation and relaxation processes, respectively, which lead to the asymmetric distribution of electrons in each spin-splitting subband. The Zeeman splitting transforms the net spin currents to charge currents. Hence, the photocurrents are proportional to the Zeeman split energy and then the electron effective g-factor g ∗. In view of this, there are no common anion and cation in the InAs/GaSb superlattice interface; this structure belongs to the C 2v symmetry. Hence, g ∗ presents in-plane anisotropy when the magnetic field is in different crystallographic directions . We speculated that the co-effect of the anisotropic SOI and g ∗ make Jpp in the  and  crystallographic directions larger.
Similar to the parameters in Equations 1 and 2, S1± denote radiation polarization unrelated currents. Linearly and circularly polarized light related currents are described by S2±, S3± and S4±, respectively. C1′ and C2′ are background currents.
Fitting results of the parameters
S 1 ′
S 2 ′
S 3 ′
S 1 +
S 1 −
S 2 +
S 2 −
S 3 +
S 3 −
ϕ is the angle between the wave vector and the x direction. α is the angle between the plane of linear polarization and the x direction. Considering the contribution of asymmetric relaxation of electrons to the current, we should add an additional term to the . Then the in Equation 6 includes contributions of both excitation and relaxation. Owing to the magneto-photocurrent in this superlattice is independent of the radiation polarization, it can be deduced that is much larger than and . This conclusion is similar to that in  which that reported always overwhelms and theoretically.
The radiation polarization independent of MPE generated by direct interband transition had also been observed in the BiTeI film . However, in (110)-grown GaAs/Al x Ga1−x As quantum wells, MPE generated by indirect intrasubband transition shows clear relations to the radiation linear polarization state . The reason may be that in the intrasubband transition process, spin-dependent asymmetric electron-phonon interaction which contributes to the magneto-photocurrent is sensitive to the radiation polarization state. It leads to the relative magnitudes of and in Equation 6 increase. More practically, the phonon effect may be taken into account when designing optically manipulated spintronics devices in the future.
Tilted magnetic field-dependent MPE
ε x i ′ and ε y i ′ are also mixing parameters due to the Hall effect. C x ′ and C y ′ are background photocurrents.
In summary, we have researched magneto-photocurrents in the InAs/GaSb superlattice when an in-plane and tilted magnetic field were applied respectively. The magneto-photocurrents in both conditions are insensitive to the polarization state of the incident light. A theoretical model involving anisotropic photo-excited carriers density is utilized to explain the in-plane magnetic field-induced MPE. Compared to the direct electron-photon interaction, the asymmetric electron-phonon interaction which contributes to the magneto-photocurrent may be more sensitive to the radiation polarization state. The quadratic magnetic field dependence of the magneto-photocurrents can be well illustrated by an additional Hall effect model.
The work was supported by the 973 Program (2012CB921304 and 2013CB632805) and the National Natural Science Foundation of China (Nos. 60990313, 61176014, 61307116 and 61290303).
- žutić I, Fabian J, Das Sarma S: Spintronics: fundamentals and applications. Rev Mod Phys 2004, 76: 323–410. doi:10.1103/RevModPhys.76.323 doi:10.1103/RevModPhys.76.323 10.1103/RevModPhys.76.323View ArticleGoogle Scholar
- Wolf SA, Awschalom DD, Buhrman RA, Daughton JM, von Molnár S, Roukes ML, Chtchelkanova AY, Treger DM: Spintronics: a spin-based electronics vision for the future. Science 2001, 294(5546):1488–1495. doi:10.1126/science.1065389 doi:10.1126/science.1065389 10.1126/science.1065389View ArticleGoogle Scholar
- Ganichev SD, Prettl W: Spin photocurrents in quantum wells. J Phys: Condens Matter 2003, 15(20):935. 10.1088/0953-8984/15/20/204Google Scholar
- Bel’kov VV, Ganichev SD: Magneto-gyrotropic effects in semiconductor quantum wells. Semiconductor Sci Technol 2008, 23(11):114003. 10.1088/0268-1242/23/11/114003View ArticleGoogle Scholar
- Dai J, Lu H-Z, Yang CL, Shen S-Q, Zhang F-C, Cui X: Magnetoelectric photocurrent generated by direct interband transitions in InGaAs/InAlAs two-dimensional electron gas. Phys Rev Lett 2010, 104: 246601. doi:10.1103/PhysRevLett.104.246601 doi:10.1103/PhysRevLett.104.246601View ArticleGoogle Scholar
- Lechner V, Golub LE, Lomakina F, Bel’kov VV, Olbrich P, Stachel S, Caspers I, Griesbeck M, Kugler M, Hirmer MJ, Korn T, Schüller C, Schuh D, Wegscheider W, Ganichev SD: Spin and orbital mechanisms of the magnetogyrotropic photogalvanic effects in GaAs/Al x Ga 1−x As quantum well structures. Phys Rev B 2011, 83: 155313. doi:10.1103/PhysRevB.83.155313 doi:10.1103/PhysRevB.83.155313View ArticleGoogle Scholar
- Drexler C, Tarasenko SA, Olbrich P, Karch J, Hirmer M, Müller F, Gmitra M, Fabian J, Yakimova R, Lara-Avila S, Kubatkin S, Wang M, Vajtai R, Ajayan M, Kono J, Ganichev SD: Magnetic quantum ratchet effect in graphene. Nat Nano 2013, 8(2):104–107. 10.1038/nnano.2012.231View ArticleGoogle Scholar
- Ting DZ-Y, Cartoixà X: Resonant interband tunneling spin filter. Appl Phys Lett 2002, 81(22):doi:10.1063/1.1524700.View ArticleGoogle Scholar
- Li J, Chang K, Hai GQ, Chan KS: Anomalous Rashba spin-orbit interaction in InAs/GaSb quantum wells. Appl Phys Lett 2008., 92(15): doi:10.1063/1.2909544 doi:10.1063/1.2909544Google Scholar
- Haugan HJ, Grazulis L, Brown GJ, Mahalingam K, Tomich DH: Exploring optimum growth for high quality InAs/GaSb type-II superlattices. J Crystal Growth 261(4):471–478. doi:10.1016/j.jcrysgro.2003.09.045 doi:10.1016/j.jcrysgro.2003.09.045Google Scholar
- Rodriguez JB, Christol P, Cerutti L, Chevrier F, Joullié A: MBE growth and characterization of type-II InAs/GaSb superlattices for mid-infrared detection. J Crystal Growth 2005, 274(1):6–13. doi:10.1016/j.jcrysgro.2004.09.088 doi:10.1016/j.jcrysgro.2004.09.088View ArticleGoogle Scholar
- Lang X-L, Xia J-B: Interface effect on the electronic structure and optical properties of InAs/GaSb superlattices. J Phys D: Appl Phys 2011, 44(42):425103. 10.1088/0022-3727/44/42/425103View ArticleGoogle Scholar
- Rodriguez JB, Plis E, Bishop G, Sharma YD, Kim H, Dawson LR, Krishna S: nBn structure based on InAs/GaSb type-II strained layer superlattices. Appl Phys Lett 2007., 91(4): doi:10.1063/1.2760153 doi:10.1063/1.2760153Google Scholar
- Wei Y, Gin A, Razeghi M, Brown GJ: Advanced InAs/GaSb superlattice photovoltaic detectors for very long wavelength infrared applications. Appl Phys Lett 2002, 80(18):3262–3264. doi:10.1063/1.1476395 doi:10.1063/1.1476395 10.1063/1.1476395View ArticleGoogle Scholar
- Yang MJ, Yang CH, Bennett BR, Shanabrook BV: Evidence of a hybridization gap in “semimetallic” InAs/GaSb systems. Phys Rev Lett 1997, 78: 4613–4616. doi:10.1103/PhysRevLett.78.4613 doi:10.1103/PhysRevLett.78.4613 10.1103/PhysRevLett.78.4613View ArticleGoogle Scholar
- Connelly BC, Metcalfe GD, Shen H, Wraback M: Direct minority carrier lifetime measurements and recombination mechanisms in long-wave infrared type II superlattices using time-resolved photoluminescence. Appl Phys Lett 2010, 97(25):251117–2511173. doi:10.1063/1.3529458 doi:10.1063/1.3529458 10.1063/1.3529458View ArticleGoogle Scholar
- Mohseni H, Litvinov VI, Razeghi M: Interface-induced suppression of the auger recombination in type-II InAs/GaSb superlattices. Phys Rev B 1998, 58: 15378–15380. doi:10.1103/PhysRevB.58.15378 doi:10.1103/PhysRevB.58.15378 10.1103/PhysRevB.58.15378View ArticleGoogle Scholar
- Luo J, Munekata H, Fang FF, Stiles PJ: Observation of the zero-field spin splitting of the ground electron subband in GaSb-InAs-GaSb quantum wells. Phys Rev B 1988, 38: 10142–10145. doi:10.1103/PhysRevB.38.10142 doi:10.1103/PhysRevB.38.10142 10.1103/PhysRevB.38.10142View ArticleGoogle Scholar
- Winkler R: Anisotropic zeeman splitting in quasi-2d systems. Springer Tracts Mod Phys 2003, 191: 131–150. doi:10.1007/978–3-540–36616–4-7 doi:10.1007/978-3-540-36616-4-7 10.1007/978-3-540-36616-4_7View ArticleGoogle Scholar
- Bel’kov VV, Ganichev SD, Ivchenko EL, Tarasenko SA, Weber W, Giglberger S, Olteanu M, Tranitz H-P, Danilov SN, Schneider P, Wegscheider W, Weiss D, Prettl W: Magneto-gyrotropic photogalvanic effects in semiconductor quantum wells. J Phys: Condens Matter 2005, 17(21):3405. 10.1088/0953-8984/17/21/032Google Scholar
- Stachel S, Olbrich P, Zoth C, Hagner U, Stangl T, Karl C, Lutz P, Bel’kov VV, Clowes SK, Ashley T, Gilbertson AM, Ganichev SD: Interplay of spin and orbital magnetogyrotropic photogalvanic effects in InSb/(Al,In)Sb quantum well structures. Phys Rev B 2012, 85: 045305. doi:10.1103/PhysRevB.85.045305 doi:10.1103/PhysRevB.85.045305View ArticleGoogle Scholar
- Lu H-Z, Zhou B, Zhang F-C, Shen S-Q: Theory of magnetoelectric photocurrent generated by direct interband transitions in a semiconductor quantum well. Phys Rev B 2011, 83: 125320. doi:10.1103/PhysRevB.83.125320 doi:10.1103/PhysRevB.83.125320View ArticleGoogle Scholar
- Ogawa N, Bahramy MS, Murakawa H, Kaneko Y, Tokura Y: Magnetophotocurrent in BiTeI with Rashba spin-split bands. Phys Rev B 2013, 88: 035130. doi:10.1103/PhysRevB.88.035130 doi:10.1103/PhysRevB.88.035130View ArticleGoogle Scholar
- Olbrich P, Allerdings J, Bel’kov VV, Tarasenko SA, Schuh D, Wegscheider W, Korn T, Schüller C, Weiss D, Ganichev SD: Magnetogyrotropic photogalvanic effect and spin dephasing in (110)-grown GaAs/Al x Ga 1−x As quantum well structures. Phys Rev B 2009, 79: 245329. doi:10.1103/PhysRevB.79.245329 doi:10.1103/PhysRevB.79.245329View ArticleGoogle Scholar
- Ganichev SD, Ivchenko EL, Bel’kov VV, Tarasenko SA, Sollinger M, Weiss D, Wegscheider W, Prettl W: Spin-galvanic effect. Nature 2002, 417(6885):153–156. 10.1038/417153aView ArticleGoogle Scholar
- Dai J, Lu H-Z, Shen S-Q, Zhang F-C, Cui X: Quadratic magnetic field dependence of magnetoelectric photocurrent. Phys Rev B 2011, 83: 155307. doi:10.1103/PhysRevB.83.155307 doi:10.1103/PhysRevB.83.155307View ArticleGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.