Strong terahertz emission from (100) p-type InAs

Abstract

Terahertz emission has been observed from (100) Zn-acceptor-doped InAs under illumination by fs pulses of near-infrared radiation. Turning the crystal about the surface normal produces two maxima per rotation, whether the angle of incidence is 45° or 75°, in contrast to (111) p-InAs, where three maxima per rotation have been reported. The emitted terahertz power has a quadratic variation with the pump power and decreases with increasing temperature in the range 20–300K. This behavior is consistent with a photocurrent surge being the dominant terahertz generating mechanism at low excitation fluences. The p-type InAs generates about two orders of magnitude more power than the standard unbiased terahertz emitter, 1mm thick ZnTe.

Intense Terahertz Radiation from InAs Thin Films

“…(The broken line is a least-squares fit obtained by assuming a linear dependence.) Surprisingly, the intensity from the 900-nm-thick InAs layer is as high as that from a bulk p-type InAs substrate, which is known to be the strongest THz source [17,18]. A similar thickness dependence (linear dependence) for InAs films on Si was reported in Ref.…”

Bulk and surface field-induced optical rectification from(11N)zincblende crystals in a quasireflection geometry

“…Such emission may be due to the current surge effect, where photocarriers are accelerated by an intrinsic surface depletion field which arises due to band bending by Fermi-level pinning of the surface states, 7 which is typically observed for wide-bandgap materials such as GaAs 8 and InP. 9,10 It may also be due to differing diffusion rates between photogenerated electrons and holes at the surface, known as the photo-Dember effect and typically observed in narrow-bandgap semiconductors with a high electron mobility such as InAs, 11,12 InSb, 13 and GaSb.…”

Terahertz Emission from GaAs Films on Si(100) and Si(111) Substrates Grown by Molecular Beam Epitaxy

“…Thin semiconductor films are often fabricated into devices such as CW photomixers or photoconductive antennae [5][6][7] while femtosecond laser-pumped semiconductor surfaces as THz pulsed emitters are generally in bulk form [8,[10][11][12][13]. In this paper, we focus on the generation of THz transients via surge current and optical rectification from femtosecond-laser-irradiated semiconductors [8][9][10][11][12][13]. At present, the best semiconductor for this purpose is p-InAs bulk crystal [8,[11][12][13] because of its relatively small carrier effective mass and low valley scattering [9].…”

“…The studies of semiconductors as THz emitters have gained much attention; either in bulk form or as thin film-based devices [5][6][7][8][9][10][11][12][13]. Thin semiconductor films are often fabricated into devices such as CW photomixers or photoconductive antennae [5][6][7] while femtosecond laser-pumped semiconductor surfaces as THz pulsed emitters are generally in bulk form [8,[10][11][12][13]. In this paper, we focus on the generation of THz transients via surge current and optical rectification from femtosecond-laser-irradiated semiconductors [8][9][10][11][12][13].…”