Ballistic photocurrents in semiconductor quantum wells caused by the excitation of asymmetric excitons

Strain-enhanced giant Rashba spin splitting in ultrathin KTaO3 films for spin-polarized photocurrents

“…We also show that such giant Rashba effect can be used to generate spin-polarized photocurrents in terms of the circular photogalvanic effect. [18][19][20][21][22][23] Therefore, these giant Rashba phenomena may open a new door to promising spintronic and optoelectronic applications.…”

“…Because of the giant Rashba spin splitting, the KTO ultrathin lms can be used for achieving circular photogalvanic effect (CPGE) to generate spin-polarized photocurrents. [18][19][20][21][22][23] For the right-handed (le-handed) circularly polarized light, its photon has the angular momentum of +1 (À1), labeled by s + (s À ), and the selection rule for necessary transitions is that the allowed zcomponent change of the total angular momentum is DJ m ¼ +1 (À1). The valence band edge, originating from the J ¼ 3/2 states, has J m ¼ AE3/2, and the conduction band edge, from the Fig.…”

“…15 Large Rashba interaction can be used to realize spin polarization and spin injection by applying electric eld 16,17 and produce spinpolarized photocurrents through polarized light. [18][19][20][21][22][23] Recently, a 2DEG was observed at KTaO 3 (KTO) (100) surface 24,25 in terms of the angle-resolved photoemission (ARPES) spectrum. 24 For another 2DEG at an amorphous-LAO/ KTO interface, an experimental analysis of the weak antilocalization effect resulted in a Rashba coupling constant 0.1 eVÅ and a 50-fold enhanced Hall mobility of charge carriers.…”

Photocurrents in GaAs quantum wires including excitonic effects

“…Depending on the formation mechanism, photocurrents can be classified into different types: ballistic, shift, and rectification currents. These photocurrents have been investigated in bulk materials [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and quantum wells (QW) [15][16][17][18][19][20][21] but have not received much attention in one-dimensional (1D) systems such as quantum wires (QWR). Here, we present a theoretical study of the photocurrents in semiconductor QWRs.…”

“…Among several models to compute the electronic band structure, we choose to use the 14-band k • p model because it is able to describe the inversion asymmetry of GaAs and can be easily applied to semiconductor heterostructures. Using this approach, we recently obtained photocurrents including excitonic effects in bulk GaAs [11] and GaAs QWs [21]. It is shown that excitonic effects not only drastically change the existing shift current but also give ©2021 Vietnam Academy of Science and Technology rise to a ballistic current which is absent if the electron-hole attraction is not included.…”