Depletion-electric-field-induced second-harmonic generation near oxidized GaAs(001) surfaces

Abstract

Second-order nonlinear mixing is evaluated as a probe of the depletion electric field in the near-surface region of GaAs͑001͒. A phenomenological model is presented whereby the nonlinear susceptibility is expanded in the depletion electric field. For GaAs, three terms contribute to the observed nonlinear mixing: the dipole-allowed bulk contribution and first-and second-order contributions in the depletion electric field. All three contributions can be isolated by a combination of rotational anisotropy and photomodulation studies. The second-harmonic signal from oxidized GaAs͑001͒ surfaces was measured as a function of azimuthal sample orientation, photomodulation, and dopant density for fundamental photon energies in the region 1.17-1.51 eV. The first-order depletion-electric-field contribution dominates the second-order contribution, and can be comparable to the intrinsic bulk contribution for high surface fields. The results rule out significant contributions arising from either bulk electric quadrupole or surface dipole effects. ͓S0163-1829͑97͒00616-4͔

Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3

“…One of such techniques employing optical second harmonic generation (SHG) is known to be sensitive to the depletion electric field and therefore seems to be suitable for this purpose, especially if it is realized in the ultrafast pump-probe configuration. [16][17][18] Another technique involves the propagation of surface acoustic waves (SAW -Rayleigh waves), which has successfully been used to study 2D electron gas in GaAs heterostructures 19,20 and magneto-conductance in Dirac cone quasiparticles of graphene. 21 The excitation of Rayleigh waves in Bi 2 Te 3 and Bi 2 Se 3 single crystals has been predicted theoretically [22][23][24] and therefore the application of SAW seems very promising for studying Dirac SS in TIs.…”

Second harmonic generation at the GaAs(111)-B|solution interface

“…For GaAs, however, the bulk response is comparatively weak, and one can selectively measure SH generation originating from the surface region. This can be achieved by suitable combinations of the polarization [2][3][4][5][6][7] and/or by changing the electronic properties of the surface, either by the deposition of a film [8][9][10] or by creating a depletion layer with a concomitant electric field [11,12]. Thus, Stehlin et al [8] used specific combinations of the polarization planes of the incident and SH beams relative to the substrate orientation in order to suppress the bulk contribution.…”

Electric‐field‐induced second‐harmonic microscopy

“…silicon, water), but is locally enhanced in regions pervaded by an electric field E 0 , which, as a polar vector, lifts inversion symmetry. This electric field-induced second-harmonic (EFISH) process, first demonstrated in the 1960s [1], has been widely employed as a probe of electric fields in semiconductor devices [2,3,4,5,6,7] and in aqueous environments [8,9,10]. However, despite extensive development of second-harmonic microscopy in other contexts [11,12,13], the potential of EFISH for diffraction-limited microscopy of electric fields remains largely untapped [14].…”