Arsenic pressure dependence of carrier lifetime and annealing dynamics for low-temperature grown GaAs studied by pump–probe spectroscopy

Abstract

Reflection-type degenerate pump-probe spectroscopy was performed for low-temperature grown (LT-) GaAs to study the effects of arsenic pressure during crystal growth and annealing on carrier lifetime and to ascertain the annealing dynamics. It was found that a sample grown under a high arsenic pressure has a shorter carrier lifetime for both as-grown and anneal conditions. It was also found that the carrier decay times of samples changed drastically when the annealing temperature was above 550 °C. We determined the annealing dynamics of LT-GaAs based on a model in which AsGa antisite defects trap photoexcited carriers. An Arrhenius plot of the carrier decay rate vs. annealing temperature in the high temperature regime gave an energy EPA that was different from the true activation energy. The annealing time dependences of EPA obtained by the two diffusion models (self diffusion and VGa vacancy assisted diffusion of defects) were compared with EPAs of our data and other works, which proved that the annealing dynamics of AsGa antisite defects was dominated by VGa vacancy assisted diffusion.

Control of the Urbach band tail and interband dephasing time with post-growth annealing in low-temperature-grown GaAs

“…30 to increase sharply to values exceeding 5 nm for anneal temperatures exceeding 550 • C. The formation of As clusters at the expense of point defects reduces the density of localization centers and thereby decreases the density and energetic extent of the band tail states. A faster evolution of the defect distribution with higher annealing temperatures 11,30,42 may have contributed to the abruptness in the change of the Urbach energy with annealing temperature observed here, in line with earlier studies of the influence of annealing on the linear absorption spectrum and carrier lifetime in LT-GaAs. 20,42,43 We note that Segschneider et al detected band tail states in an LT-GaAs sample that had been annealed at 600 • C using nonlinear pump probe spectroscopy.…”

“…A faster evolution of the defect distribution with higher annealing temperatures 11,30,42 may have contributed to the abruptness in the change of the Urbach energy with annealing temperature observed here, in line with earlier studies of the influence of annealing on the linear absorption spectrum and carrier lifetime in LT-GaAs. 20,42,43 We note that Segschneider et al detected band tail states in an LT-GaAs sample that had been annealed at 600 • C using nonlinear pump probe spectroscopy. 15 The persistence of the band tail in the experiments of Ref.…”

Low threshold InGaAsN/GaAs lasers beyond 1500nm

“…The same increase in the N content of InGaAsN quantitatively explains the redshift in PL wavelength. The beneficial effect of small V/III ratios on material grown at low temperatures is generally attributed to the reduction of As interstitials [8], Ga vacancies [9] and antisite defects [10]. However, it is unclear why the application of this concept to the growth of InGaAsN has not been reported yet.…”

Annealing dynamics of As ion-implanted GaAs: As Ga antisite defect model

“…Therefore, the origins of the short carrier trap time and annealing dynamics have been extensively studied by many researchers. [2][3][4][5][6][7][8][9][10][11][12][13][14][15] In the defect-band (As Ga antisite defect) model, short carrier trap time τ CL has been attributed to the high density of As Ga antisite defects. As Ga defects are considered to migrate and eventually be captured by As precipitates during the annealing process.…”