Lattice parameter, RBS channeling, and T-dependent Hall effect and resistivity are measured in 5 μm GaAs layers MBE-grown at 200°C, 250°C and 305°C, and subsequently annealed. Perpendicular lattice parameter was increased by 0.15% for 200 °C, 0.10% for 250°C, and 0.05% for 305°C sample. No parallel mismatch was observed. In annealing up to 800°C, most recovery of lattice parameter occured at 350°C-450°C. For samples annealed at 500° C − 600°C, the conductivity activation energy was higher in the furnace annealed sample than in the RTA-annealed sample, indicating possible depth nonuniformity in furnace annealed sample. The 600°C RTA annealed sample indicated a donor activation energy of 0.61 eV. A 600°C furnace annealed sample indicated the deep donor concentration of 1.5×1018 cm−3. Maximum mobility in the 500–600°C annealed sample was 3000–3500 cm2/Vs, limited by the neutral impurity scattering and polar optical phonon scattering.