Infrared measurements in annealed molecular beam epitaxy GaAs grown at low temperature

Abstract

We have utilized an infrared absorption technique to study deep level defects in molecular beam epitaxy GaAs grown at 250 °C. From an observed broad absorption band below the conduction edge, the concentration of defects is estimated to be ≊5×1019 cm−3 in an as-grown sample. The concentration of defects decreases exponentially by one order of magnitude due to annealing of the sample at temperatures of 400–500 °C. From the temperature dependence of the defect concentration, the migration energy of defects is calculated to be 0.52±0.02 eV. The measured migration energy shows that part of the defects are arsenic interstitials.

Arsenic interstitials and interstitial complexes in low-temperature grown GaAs

“…Slow positron annihilation studies 10 have been used to demonstrate the existence of Ga vacancies in LT GaAs, and both rapid diffusion 11 and ion channeling 12 experiments have been cited as evidence of the existence of As interstitials in LT GaAs. However, these experiments do not provide such an unambiguous, quantitative measure of the concentrations of Ga vacancies and As interstitials as the EPR and absorption experiments do for As antisites.…”

The effect of Bi composition to the optical quality of GaAs1−xBix

“…The results suggest that the incorporation of Bi in GaAs of up to $0.025 improves the material quality. It is well known that growing GaAs at significantly lower than the optimal growth temperature (580 C) induces many defects such as As-related defects (As-interstitial 15 and As-antisite, As Ga 16 ) and Ga vacancies. 17 Incorporating Bi during low temperature growth enhances surface migration, thus reducing the density of Ga and/or As-related defects.…”

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

“…8,9,27 However, it was accidental that a value of E PA similar to a certain activation energy was obtained. Activation energy cannot be obtained from an Arrhenius plot of data if the vertical axis is an annealing-time-dependent value (for example, an absorption coefficient of the defect or a carrier decay rate).…”

“…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.…”