Annealing Effect on Photoluminescence Properties of Be-Doped MBE GaAs

Abstract

AbstractLow temperature (2° K) photoluminescence (PL) measurements were performed for the wavelength (λ) region from 800 to 1600 nm on Be–doped GaAs grown by molecular beam epitaxy (MBE) for wide range of net hole concentration at room temperature (p) up to 2 x 1020 cm−3 after annealing at 850 °C for 20 minutes. The annealing procedure formed several new PL emission bands associated with deep levels appeared between 0.4 and 1.4 eV. The most intensive new PL band appeared at around 1.2 eV with a band width of about 0.2 eV for all samples investigated. Its peak position and band width were observed to shift slightly toward lower energy side and increase, respectively with increasing p. An additional two sharp bands appeared overlapping the main band at around 1.31 and 1.35 eV for p less than 1 x 1018 cm−3. New broad band formation was also observed at around 1.0 eV in the same samples. In addition, a new prominent PL band was found at about 1.35 eV in the as-grown samples with p = 5 ∼ 6 x 1017 cm−3, which disappeared entirely after annealing. The formation and annihilation mechanism of these deep levels after annealing can be presumably attributed to Be redistribution from Ga sites to As sites and interstitial sites to Ga or As sites, driven by the formation of As vacancies (V As) due to As evaporation from samples during annealing.