Terahertz emission from InAs induced by photo-Dember effect: Hydrodynamic analysis and Monte Carlo simulations

Abstract

Terahertz emission from InAs excited by the femtosecond optical pulse is investigated. The hydrodynamic model is developed for the simplified analysis of the terahertz emission induced by the photo-Dember effect. The hydrodynamic model predicts that the amplitude of the transient photocurrent is proportional to the difference between the squared velocities of photoexcited electrons and holes. The predictions of the hydrodynamic model are compared to the results of the rigorous ensemble Monte Carlo simulations. The dependences of the intensity of terahertz emission on the optical fluence, on the photon energy, and on the optical pulse duration are studied. At low intensities of the optical pulse, the emitted terahertz energy is proportional to the power ranging between 3/2 and 2 of the optical pulse intensity. The emitted terahertz energy saturates at high intensities of the optical pulse. The spectral dependence of the terahertz emission from InAs is investigated. It is found that the intensity of terahertz emission profoundly depends on the optical pulse duration.

Terahertz surfoluminescence

“…The electromagnetic radiation is then calculated from the time derivative of current density. This is broadly the same general method used by a number of others in accounting for the terahertz radiation produced by ultrafast optical excitation of semiconductor surfaces [8][9][10][11][12][13][14][15][16]. Monte Carlo methods have superseded the analytical approach to surface generation of terahertz radiation, a point illustrated by the earlier analytical [17] and later Monte Carlo [13] modeling of Malevich.…”

Генерация терагерцового излучения при облучении фемтосекундными лазерными импульсами In-=SUB=-0.38-=/SUB=-Ga-=SUB=-0.62-=/SUB=-As, выращенного на подложке GaAs с метаморфным буферным слоем

“…В результате того, что подвижность электронов, как правило, выше подвижности дырок, в полупроводнике при поглощении оптического излуче-ния возникает пространственное разделение электронно-дырочных пар и, как следствие импульс тока, кото-рый генерирует ТГц излучение. Фотоэффект Дембера сильнее проявляется в полупроводниках с узкой за-прещенной зоной, например InAs или InN [17][18][19], а эффект ускорения электрон-дырочных пар встроенным электрическим полем -в полупроводниках с широкой запрещенной зоной, например GaAs..…”

Oscillations of electron–hole plasma in terahertz emitters

“…The downward band bending is neglected in the hydrodynamic model of the photo-Dember effect developed in [20]. It is assumed that the potential is constant throughout the structure prior to photogeneration.…”

“…For the valence band, heavy, light, and split-off nonparabolic subbands are taken into account. The band structure and material parameters for GaAs and InAs are taken the same as in [19] and [20], respectively. The electron scattering mechanisms considered in the simulations include polar optical, inelastic deformation acoustic, intervalley, and ionized impurity scattering, as well as electron-electron and electron-hole interactions.…”

“…This assumption is justified by the fact that the kinetic energy of excited carriers exceeds the energy of electron confinement due to downward band bending. Then, the hydrodynamic model [20] gives the total photocurrent as (6) where…”