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In this paper, the ultrafast dynamics of spin relaxation and recombination of photoexcited carriers has been studied in (001) GaAs quantum wells using a time-resolved pump-probe absorption spectroscopy under a nearly resonant excitation of heavy-hole excitons. It is found that the spin polarization of carriers influences both absorption saturation of linear polarized light and recombination dynamics of carriers. Pump fluence dependence of the ultrafast dynamics of spin relaxation and recombination of carriers is further studied, which shows that the effect of spin polarization on linearly polarized absorption saturation is reduced with lowering pump fluence. Spin-polarization-dependent absorption saturation effect can be ignored only as the pump fluence is weak. However, spin-polarization dependence of recombination dynamics is presented in turn at low pump fluence. Our analysis shows that such dependence originates from the spin-polarization dependence of the density of excitons formed in the excited carriers because recombination time constants of excitons and free carriers are very different so that the ratio of exciton density to free carrier density can influence the recombination dynamics. The spin-polarization dependence of ultrafast recombination dynamics of photoexcited carriers implies that the recombination time constant in the calculation of spin relaxation time from spin relaxation dynamics should be the recombination time of spin-polarized carriers, rather than the recombination lifetime of non-spin-polarized carriers as done currently. Exciton density is estimated based on 2D mass action law, which agrees very well with our experimental results. The good agreement between theoretical calculation and experimental results reveals that the effect of Coulomb screening on the formation of excitons may be ignored for a lower excited carrier density.
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Keywords:
- circularly polarized pump-probe spectroscopy /
- GaAs quantum wells /
- absorption saturation /
- recombination dynamics
[1] Wolf S A, Awschalom D D, Buhrman R A, Daughton J M, Von Molna S, Roukes M L, Chtchelkanova A Y, Treger D M 2001 Science 294 1488
[2] Lai T S, Teng L H, Jiao Z X, Xu H H, Lei L, Wen J H, Lin W Z 2007 Appl. Phys. Lett. 91 062110
[3] Teng L H, Yu H L, Zuo F Y, Wen J H, Lin W Z, Lai T S 2008 Acta Phys. Sin. 57 6598 (in Chinese) [滕利华, 余华梁, 左方圆, 文锦辉, 林位株, 赖天树 2008 物理学报 57 6598]
[4] Zhao C B, Yan T F, Ni H Q, Niu Z C, Zhang X H 2013 Appl. Phys. Lett. 102 012406
[5] Yu H L, Zhang X M, Wang P F, Ni H Q, Niu Z C, Lai T S 2009 Appl. Phys. Lett. 94 202109
[6] Weber C P, Gedik N, Moore J E, Orenstein J, Stephens J, Awschalom D D 2005 Nature 437 1330
[7] Wu M W, Jiang J H, Weng M Q 2010 Physics Reports 493 61
[8] Chen K, Wang W F, Wu J D, Schuh D, Wegscheider W, Korn T, Lai T S 2012 Optics Express 20 8192
[9] Ma H, Jin Z M, Ma G H, Liu W M, Tang S H 2009 Appl. Phys. Lett. 94 241112
[10] Luo H H, Qian X, Ruan X Z, Ji Y, Umansky V 2009 Phys. Rev. B 80 193301
[11] Chai Z, Hu M J, Wang R Q, Hu L B 2014 Chin. Phys. B 23 027201
[12] Gu X F, Qian X, Ji Y, Chen L, Zhao J H 2011 Chin. Phys. B 20 087503
[13] Weng M Q, Wu M W 2003 Phys. Rev. B 68 075312
[14] Stich D, Zhou J, Korn T, Schulz R, Schuh D, Wegscheider W, Wu M W, Schller C 2007 Phys. Rev. B 76 205301
[15] Stich D, Zhou J, Korn T, Schulz R, Schuh D, Wegscheider W, Wu M W, Schller C 2007 Phys. Rev. Lett. 98 176401
[16] Teng L H, Yu H L, Huang Z L, Wen J H, Lin W Z, Lai T S 2008 Acta Phys. Sin. 57 6593 (in Chinese) [滕利华, 余华梁, 黄志凌, 文锦辉, 林位株, 赖天树 2008 物理学报 57 6593]
[17] Teng L H, Wang X, Ge W, Lai T S 2011 Semicond. Sci. Technol. 26 095012
[18] Kumar R, Prabhu S S, Vengurlekar A S 1997 Phys. Scripta 56 308
[19] Chemla D S, Miller D A B, Smith P W, Gossard A C, Wiegmann W 1984 IEEE J. Quan. Elec. 20 265
[20] Christen J, Bimberg D 1986 Surface Sci. 174 261
[21] Gulia M, Rossi F, Molinari E, Selbmann P E, Lugli P 1997 Phys. Rev. B 55 R16049
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[1] Wolf S A, Awschalom D D, Buhrman R A, Daughton J M, Von Molna S, Roukes M L, Chtchelkanova A Y, Treger D M 2001 Science 294 1488
[2] Lai T S, Teng L H, Jiao Z X, Xu H H, Lei L, Wen J H, Lin W Z 2007 Appl. Phys. Lett. 91 062110
[3] Teng L H, Yu H L, Zuo F Y, Wen J H, Lin W Z, Lai T S 2008 Acta Phys. Sin. 57 6598 (in Chinese) [滕利华, 余华梁, 左方圆, 文锦辉, 林位株, 赖天树 2008 物理学报 57 6598]
[4] Zhao C B, Yan T F, Ni H Q, Niu Z C, Zhang X H 2013 Appl. Phys. Lett. 102 012406
[5] Yu H L, Zhang X M, Wang P F, Ni H Q, Niu Z C, Lai T S 2009 Appl. Phys. Lett. 94 202109
[6] Weber C P, Gedik N, Moore J E, Orenstein J, Stephens J, Awschalom D D 2005 Nature 437 1330
[7] Wu M W, Jiang J H, Weng M Q 2010 Physics Reports 493 61
[8] Chen K, Wang W F, Wu J D, Schuh D, Wegscheider W, Korn T, Lai T S 2012 Optics Express 20 8192
[9] Ma H, Jin Z M, Ma G H, Liu W M, Tang S H 2009 Appl. Phys. Lett. 94 241112
[10] Luo H H, Qian X, Ruan X Z, Ji Y, Umansky V 2009 Phys. Rev. B 80 193301
[11] Chai Z, Hu M J, Wang R Q, Hu L B 2014 Chin. Phys. B 23 027201
[12] Gu X F, Qian X, Ji Y, Chen L, Zhao J H 2011 Chin. Phys. B 20 087503
[13] Weng M Q, Wu M W 2003 Phys. Rev. B 68 075312
[14] Stich D, Zhou J, Korn T, Schulz R, Schuh D, Wegscheider W, Wu M W, Schller C 2007 Phys. Rev. B 76 205301
[15] Stich D, Zhou J, Korn T, Schulz R, Schuh D, Wegscheider W, Wu M W, Schller C 2007 Phys. Rev. Lett. 98 176401
[16] Teng L H, Yu H L, Huang Z L, Wen J H, Lin W Z, Lai T S 2008 Acta Phys. Sin. 57 6593 (in Chinese) [滕利华, 余华梁, 黄志凌, 文锦辉, 林位株, 赖天树 2008 物理学报 57 6593]
[17] Teng L H, Wang X, Ge W, Lai T S 2011 Semicond. Sci. Technol. 26 095012
[18] Kumar R, Prabhu S S, Vengurlekar A S 1997 Phys. Scripta 56 308
[19] Chemla D S, Miller D A B, Smith P W, Gossard A C, Wiegmann W 1984 IEEE J. Quan. Elec. 20 265
[20] Christen J, Bimberg D 1986 Surface Sci. 174 261
[21] Gulia M, Rossi F, Molinari E, Selbmann P E, Lugli P 1997 Phys. Rev. B 55 R16049
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