Growth temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy

We have quantitatively studied the temperature dependence of the surface segregation of Er atoms in GaAs during molecular beam epitaxy using secondary ion mass spectroscopy. It was found that a significant number of Er atoms segregate to the growing surface at temperatures of 400°C and above and that the segregation decay length is approximately 0.5 µm at 500°C, indicating that the incorporation ratio of Er atoms into GaAs is less than 10^-3. In contrast to the growth at higher temperatures, GaAs overlayer growth at a temperature as low as 300°C is effective in suppressing the surface segregation of Er and obtaining δ-doped structures. (author)