Direct MBE growth of GaN on GaAs substrates for integrated short wavelength emitters

The growth and material properties of GaN heteroepitaxial layers on vicinal (100) and exact (111)B substrates have been investigated, using molecular beam epitaxy (MBE) with N-2 RF-plasma source. We examined the approach to g row GaN directly on the oxide desorbed GaAs, without the incidence of an As beam during oxide desorption or the following stages of growth. Perfect sm ooth surfaces were obtained on (111)B GaAs but excellent luminescence prope rties were observed on vicinal (100) GaAs. four growth temperatures (T-G) w ere compared for the (100) orientation and a monotonic increase of photolum inescence intensity with increasing T-G, in the range of 570-680 degreesC, was observed. The best surface morphology of less than 10 nm mts roughness was also determined, by atomic force microscopy, for the maximum (680 degre esC) temperature. The layers exhibited up to 10(17) cm(-3) electron concent ration and it could be compensated by Mg impurities. Metallizations of Pt a nd Pd gave ohmic contacts on GaN/GaAs (100) but a Schottky diode contact wa s achieved by Ir metallization. The obtained material properties are probab ly sufficient for realizing efficient GaN light emitters on (100) GaAs subs trates. (C) 2001 Elsevier Science Ltd. All rights reserved.