“On the Growth - and Annealing - Temperature Dependence of the Electrical Properties of Ga0.51In0.49P/GaAs Heterostructures Grown by Mombe”

ABSTRACTWe study the effect of growth temperature (TG) and post-growth rapid thermal annealing (RTA) on the electrical properties of Schottky diodes fabricated on undoped, lattice-matched Ga0.51In0.49P/GaAs heterostructures. The samples were grown by metalorganic molecular beam epitaxy (MOMBE) in the temperature range 480 – 560°C. Ga0.51In0.49P grown in this temperature range undergoes spinodal decomposition, as shown by cross-section TEM analysis. The dislocation-free epilayers grown at TG≤520°C are characterized by a deep electron trap with an activation energy of 800meV while growth at higher temperatures renders trap-free films. Furthermore, the Schottky barrier ideality factor (n) depends strongly on TG and takes the best value of 1.4 for TG=540°C, while the barrier height remains nearly constant at about 0.75eV. Finally, upon capped rapid thermal annealing the value of n improves while the trap concentration decreases significantly. Based on the presented experimental evidence we can propose that MOMBE growth at 540°C renders films with improved electrical properties.