Photoconductive terahertz generation from textured semiconductor materials

Abstract

Photoconductive (PC) terahertz (THz) emitters are often limited by ohmic loss and Joule heating—as these effects can lead to thermal runaway and premature device breakdown. To address this, the proposed work introduces PC THz emitters based on textured InP materials. The enhanced surface recombination and decreased charge-carrier lifetimes of the textured InP materials reduce residual photocurrents, following the picosecond THz waveform generation, and this diminishes Joule heating in the emitters. A non-textured InP material is used as a baseline for studies of fine- and coarse-textured InP materials. Ultrafast pump-probe and THz setups are used to measure the charge-carrier lifetimes and THz response/photocurrent consumption of the respective materials and emitters. It is found that similar temporal and spectral characteristics can be achieved with the THz emitters, but the level of photocurrent consumption (yielding Joule heating) is greatly reduced in the textured materials.

Review of terahertz photoconductive antenna technology

“…57,80,86,91,92 Thus far, the most studied and promising materials for THz PCAs have included bulk gallium arsenide (GaAs), [51][52][53][54][55][56][57][58][59][60][61][62][63][64] bulk indium gallium arsenide (InGaAs), 69,87,[93][94][95][96][97][98][99] alternating nanoscale multilayers of InGaAs and indium aluminum arsenide (InAlAs), [100][101][102][103][104][105][106][107] and select other group III-VI semiconductors. 91,[108][109][110][111] The following sections will individually address each material system, reviewing key works and summarizing their unique contributions and applications to the development of THz PCA technology.…”

“…Although GaAs and InGa(Al)As are the most widely studied material systems for THz PCA development, several other group III-V materials have been investigated as well. 66,[108][109][110][111]119,120 THz emission in antimony (Sb) based materials, such as InSb, 108 GaAsSb, 109 GaSb, 119 and GaInSb, 120 has been studied by several groups, although only the work of Sigmund et al 109 fabricated and characterized THz PCAs on the material. 1-THz bandwidths were observed in a THz TDS system utilizing GaAsSb material in the PCA emitter and detector, although more study of the growth conditions is needed to fully evaluate the potential of this material for THz PCAs.…”

“…66 In all cases, the rare-earth arsenidebased photomixers outperformed LT-GaAs photomixers at operation frequencies below 1 THz, though output power was higher in LT-GaAs for higher frequencies. 66 Collier et al 111 fabricated THz PCAs on InP to study the effects of surface roughness on the THz emission. Although surface roughness showed no effect on the amplitude and bandwidth of THz emission, around 1 order of magnitude suppression of the photocurrent was observed.…”

Электрические и тепловые свойства фотопроводящих антенн на основе In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-As (x>0.3) с метаморфным буферным слоем для генерации терагерцового излучения

“…Это сопровождается выделени-ем джоулева тепла [21] одновременно с нагревом от воздействия оптической накачки лазером, что приводит к тепловому пробою антенны. В [22] было показано, что использование теплоотводящих элементов может заметно снизить максимальную температуру работы ФА, а в [20] авторы показали, что на величину темнового тока и отвод тепла влияет металлизация электродов.…”

Integration And Simulation Of Microfluidic Platforms And Terahertz Time-Domain Spectroscopy Systems

“…Ultrafast science and measurement of terahertz (THz) electromagnetic radiation is a rapidly-growing research area with many applications [1][2][3][4][5][6][7]. Terahertz electromagnetic radiation occupies a unique section of the electromagnetic spectrum, being 0.1-10 THz.…”