Arsenic precipitates and the semi-insulating properties of GaAs buffer layers grown by low-temperature molecular beam epitaxy

Warren, A.C.; Woodall, J. M.; Freeouf, J. L.; Grischkowsky, D.; McInturff, D.; Melloch, M. R.; Ōtsuka, N.

doi:10.1063/1.103474

Cited by 444 publications

(116 citation statements)

References 9 publications

Supporting

Mentioning

112

Contrasting

Unclassified

Order By: Relevance

“…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.…”

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

View full text Add to dashboard Cite

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...

show abstract

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

View full text Add to dashboard Cite

show abstract

“…By annealing the LT-GaAs samples, the EL2-like As Ga antisite defects precipitate into As clusters. 12 To avoid As evaporation during annealing, the samples were placed face down on a GaAs substrate. One piece of sample C was annealed at 600°C using the same procedure.…”

mentioning

confidence: 99%

Above band gap absorption spectra of the arsenic antisite defect in low temperature grown GaAs and AlGaAs

Dankowski

Streb

Ruff

et al. 1996

Applied Physics Letters

View full text Add to dashboard Cite

“…Numerous studies have demonstrated that as-grown LT-GaAs contains t> 1% excess arsenic, producing a large concentration of As antisite-related defects (101~-102° cm 3), and that it also has a = 0.1% larger lattice constant than its bulk GaAs substrate [15,16]. The as-grown phase of LT-GaAs is known to have relatively low resistivity and mobility, so that even though it possesses a fast carrier response, it is not an outstanding photoconductor.…”

Section: Ultrashort Carrier Lifetimementioning

confidence: 99%

Optoelectronic applications of LTMBE III–V materials

Whitaker

1993

Materials Science and Engineering: B

View full text Add to dashboard Cite

A review of the application of semiconductor layers grown at low substrate temperatures to ultrafast optoelectronics is presented. The films, grown by molecular beam epitaxy primarily around 200 °C and subsequently annealed, are demonstrated to have high resistivity, high mobility, an ultrashort carrier lifetime, and a high dielectric breakdown. This combination of properties makes the low-temperature-grown materials perfectly suited for use in high-speed optoelectronic devices. A number of issues which influence the application of these materials, such as growth temperature, use of an annealing process, layer thickness, and optical wavelength, are considered. Examples of low-temperature-grown semiconductor optoelectronic devices, including ultra-high-bandwidth photoconductive detectors, high-sensitivity, highbandwidth MSM photodetectors, and optical temporal analyzers are demonstrated. While the discussion concentrates on low-temperature-grown GaAs, the lattice-mismatched ternary compound InxGa ~ _xAs/GaAs is also considered in the context of detection of the longer wavelengths used in optical communications.

show abstract

Arsenic precipitates and the semi-insulating properties of GaAs buffer layers grown by low-temperature molecular beam epitaxy

Cited by 444 publications

References 9 publications

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

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

Above band gap absorption spectra of the arsenic antisite defect in low temperature grown GaAs and AlGaAs

Optoelectronic applications of LTMBE III–V materials

Contact Info

Product

Resources

About