Carrier lifetime versus anneal in low temperature growth GaAs

Harmon, E. S.; Melloch, M. R.; Woodall, J. M.; Nolte, David D.; Ōtsuka, N.; Chang, C. L.

doi:10.1063/1.110542

Cited by 169 publications

(86 citation statements)

References 18 publications

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“…By annealing the material, arsenic clusters are formed [31]which act as efficient traps for photo-induced carriers. Carrier lifetimes shorter than 500 fs can be achieved with this method [32][33][34]Similarly short carrier lifetimes can also be achieved with erbium nano islands embedded in GaAs [35]. Generally, there is a trade-off between optimally short carrier lifetimes and increased parasitic dark current leading to premature breakdown of the material.…”

Section: 2materials Considerationsmentioning

confidence: 96%

Intense ultrashort terahertz pulses: generation and applications

Hoffmann¹,

Fülöp²

2011

J. Phys. D: Appl. Phys.

332

215

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Ultrashort terahertz pulses derived from femtosecond table-top sources have become a valuable tool for time-resolved spectroscopy during the last two decades. Until recently, the pulse energies and field strengths of these pulses have been generally too low to allow for the use as pump pulses or the study of nonlinear effects in the terahertz range. In this review article we will describe methods of generation of intense single cycle terahertz pulses with emphasis on optical rectification using the tilted-pulse-front pumping technique. We will also discuss some applications of these intense pulses in the emerging field of nonlinear terahertz spectroscopy.

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Section: 2materials Considerationsmentioning

confidence: 96%

Intense ultrashort terahertz pulses: generation and applications

Hoffmann¹,

Fülöp²

2011

J. Phys. D: Appl. Phys.

332

215

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“…In postgrowth annealed LT GaAs, As precipitates of a few nm in diameter nucleate. 5 The density of precipitates and point defects can be tailored with T g and T a and hence the electronic and optic properties can differ largely as a function of these temperatures. Two competing models have been proposed for explaining the properties of LT GaAs.…”

mentioning

confidence: 99%

Energy resolved ultrafast relaxation dynamics close to the band edge of low-temperature grown GaAs

Segschneider

Dekorsy

Kurz

et al. 1997

Applied Physics Letters

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We investigate the relaxation dynamics of photogenerated carriers in low-temperature grown GaAs by femtosecond pump-probe measurements. The carrier dynamics in the vicinity of the band edge is disentangled in a two-color technique. The filling of shallow bound states close beneath the band edge is resolved. A temporal delay in the occupation of these states as well as a large optical nonlinearity points towards microscopic potential fluctuations forming these states. © 1997 American Institute of Physics. ͓S0003-6951͑97͒00345-8͔In the last few years the interest in low-temperature grown ͑LT͒ semiconductors rapidly increased because of their unique electrical and optical properties and the resulting wide range of optoelectronic applications. The most promising material is LT GaAs grown at temperatures T g ϭ180°Ϫ300°C by molecular beam epitaxy ͑MBE͒. After annealing at T a ϭ400°Ϫ800°C LT GaAs exhibits an extraordinary high resistance in conjunction with a relatively high photocarrier mobility. 1 Important for THz devices are ultrashort carrier lifetimes in LT GaAs, which can be tailored into the sub-picosecond range. 2-4 All these properties are assigned to the large excess of As ͑1%-2%͒ incorporated during the growth process. In postgrowth annealed LT GaAs, As precipitates of a few nm in diameter nucleate. 5 The density of precipitates and point defects can be tailored with T g and T a and hence the electronic and optic properties can differ largely as a function of these temperatures. Two competing models have been proposed for explaining the properties of LT GaAs. In the defect model, EL2-like point defects stemming from excess As play the most important role. 6 The alternative model assigns the properties of LT GaAs to the formation of As-clusters in a buried Schottkybarrier model. 7 Ultrashort carrier lifetimes are attributed to either trapping in point defects or in As clusters.Presently, LT GaAs is used in photomixing, 8 ultrafast photoconductive switches or substrate material for THz antennas. 9,10 For an optimum performance of these devices the lifetime of photogenerated carriers is crucial. The device bandwidth should be closely related to 1/ , where is the lifetime of mobile carriers. However, a distinct difference is often observed between and the device bandwidth, which can be more than a factor of 2 smaller than 1/ . On the one hand, this difference certainly is influenced by the capacity and the impedance matching of the device, on the other hand carriers trapped in shallow potentials may be reexcited thermally or by the THz electric fields, thus reducing the optimum performance concerning bandwidth and noise.In this letter, we carefully inspect the dynamics of photogenerated carriers close to the band edge in thin LT GaAs films. Two color time-resolved transmission changes allow to resolve the carrier relaxation close to the band edge with high energetic and temporal resolution. We obtain information on shallow bound sub-band-gap states and point out their relevance for the optoelectronic properties...

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“…Поэтому при оптическом возбуждении структуры LT-GaAs способны генерировать пикосекундные (и более короткие) электрические импульсы, имеющие спектральный максимум в THz-области [3]. В большинстве исследований по созданию LT-GaAs [4,5] постросто-вый отжиг проводится в in situ в камере эпитаксиальной установки при температурах до 600…”

Section: поступило в редакцию 3 июля 2017 гunclassified

Влияние режима отжига на свойства терагерцевой фотопроводящей антенны на основе LT-GaAs

Nomoev¹,

Васильевский²,

Виниченко³

et al. 2018

Письма В Журнал Технической Физики

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Методом молекулярно-лучевой эпитаксии выращены пленки LT-GaAs (low temperature gallium arsenide -арсенид галлия, выращенный методом моле-кулярно-лучевой эпитаксии при низкой температуре роста) на подложках GaAs(100) при температуре 230• C и проведен постростовый отжиг. На поверх-ности пленок изготовлены фотопроводящие антенны с флажковой геометрией. Получены мощностные зависимости терагерцевого отклика при различных значениях напряжения смещения и температуры постростового отжига. Ме-тодом терагерцевой спектроскопии исследованы спектральные характеристики изготовленных фотопроводящих антенн. Определен диапазон оптимальной температуры постростового отжига (670−720• C) пленок LT-GaAs.

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Carrier lifetime versus anneal in low temperature growth GaAs

Cited by 169 publications

References 18 publications

Intense ultrashort terahertz pulses: generation and applications

Intense ultrashort terahertz pulses: generation and applications

Energy resolved ultrafast relaxation dynamics close to the band edge of low-temperature grown GaAs

Влияние режима отжига на свойства терагерцевой фотопроводящей антенны на основе LT-GaAs

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