Terahertz emission from narrow gap semiconductors photoexcited by femtosecond laser pulses

Large increase in the emitted terahertz power was observed for p-InAs samples with the p-doping levels of approximately 10 16 −10 17 cm −3 . This increase was explained by a large surface depletion layer and an electric-field--induced optical rectification effect in the layer. Terahertz fields radiated by the samples of all three investigated CdxHg1−xTe layers was of the same order of magnitude. No azimuthal angle dependence of the radiated signal was detected, which evidences that linear current surge effect is dominating over nonlinear optical rectification. Azimuthal angle and magnetic fields emission witness that it is caused by linear photo-Dember type processes

Terahertz Emission from the Surfaces of InAs and Other Narrow-Gap Semiconductors

THz pulses were used to investigate carrier dynamics in narrow-gap semiconductors. The measurement of the optically induced THz pulse absorption transients provided important insights into electron energy relaxation in the conduction band. In the second set of experiments, THz generation from the surfaces of various semiconductors was studied and compared. It was found that the most efficient THz emitters are semiconductors with a narrow band gap, large intervalley separation in the conduction band, and low nonparabolicity of the main valley

Terahertz Emission from Narrow Gap Semiconductors Photoexcited by Femtosecond Laser Pulses

Large increase in the emitted terahertz power was observed for p-InAs samples with the p-doping levels of approximately 10 16 −10 17 cm −3 . This increase was explained by a large surface depletion layer and an electric-field--induced optical rectification effect in the layer. Terahertz fields radiated by the samples of all three investigated CdxHg1−xTe layers was of the same order of magnitude. No azimuthal angle dependence of the radiated signal was detected, which evidences that linear current surge effect is dominating over nonlinear optical rectification. Azimuthal angle and magnetic fields emission witness that it is caused by linear photo-Dember type processes

Optical Pump - Terahertz Probe Measurement of the Electron Dynamics in Ga1−x\text{}_{1-x}Mnx\text{}_{x}As

An optical pump - terahertz probe technique was used for measuring electron lifetime in various Ga$\text{}_{1-x}$Mn$\text{}_{x}$As epitaxial layers with the subpicosecond temporal resolution. The measurements were performed on the samples with x up to 2%, which had large resistivities and were transparent in a THz frequency range. It has been found that an induced THz absorption relaxation is the fastest and electron lifetimes are the shortest for the samples with the smallest Mn content. For the samples with x=0.3% and x=2% this relaxation becomes much slower; its rate is comparable to the carrier recombination rate in Ga$\text{}_{1-x}$Mn$\text{}_{x}$As substrate

Puslaidininkės medžiagos ultrasparčiajai optoelektronikai

The paper presents a review of experimental investigations of various semiconductor materials used for the development of ultrafast optoelectronic devices activated by femtosecond laser pulses that have been performed at the Optoelectronics Laboratory of the Semiconductor Physics Institute during the period from 1997 to 2008. Technology and physical characteristics of low-temperature-grown GaAs and GaBiAs layers as well as the effect of terahertz radiation from the femtosecond laser excited semiconductor surfaces are described and analysed.Lietuviška santrauka. Pateikta įvairių puslaidininkinių medžiagų, naudojamų kuriant ultrasparčius optoelektronikos prietaisus, žadinamus femtosekundiniais lazeriais, ekspwerimentinių tyrimų apžvalga. Tyrimai atlikti Puslaidininkių fizikos instituto Optoelektronikos laboratorijoje1997-2008 metais. Aprašyta žemoje temperatūroje augintų GaAs ir GaBiAssluoksnių technologija ir fizikinės savybės. Išsamiai aptyartas ir išanalizuotas THz spinduliuotės generavimas iš femtosekundiniu lazeriu sužadintų puslaidininkių paviršiaus

Low-Temperature MBE Grown GaAs for Pulsed THz Radiation Applications

Attempts to optimize recombination characteristics of low-temperature MBE grown GaAs layers for their use in terahertz radiation devices are described and the characteristics of this material are compared with its alternative - As-ion implanted GaAs crystals

Low-Temperature MBE Grown GaAs for Pulsed THz Radiation Applications

Attempts to optimize recombination characteristics of low-temperature MBE grown GaAs layers for their use in terahertz radiation devices are described and the characteristics of this material are compared with its alternative - As-ion implanted GaAs crystals