Confinement of excess arsenic incorporated in thin layers of mbe-grown low-temperature GaAs

This chapter presents results on the optical properties of single and multiple quantum well structures incorporating thin layers of Low-Temperature GaAs (LTGaAs) within barriers and well regions respectively. GaAs epilayers grown at low substrate temperatures under otherwise normal molecular beam epitaxy growth conditions are currently attracting much interest due to their unique electrical properties. The LTGaAs layers are very thin and it has been shown that annealing at T_sub >580°C for 10 mins. is sufficient to remove the lattice mismatch to GaAs even for bulk layers of LTGaAs. In the case of the 150Å well, whose position in the growth means that it always sees unannealed LTGaAs, the effects are different. The decreased efficiency of the two annealed samples is probably due largely to the long anneal in an As₄ overpressure, rather than the LTGaAs.