In situ characterization of GaAs growth in nitrogen atmosphere during MOVPE: a comparison to hydrogen atmosphere

The influence of the carrier gas atmosphere is investigated in situ for GaA s in the temperature range between 670 and 990 K by means of reflectance an isotropy spectroscopy (RAS), During growth (dynamic conditions), diffusion lengths of the growth determining Ga-species are nearly identical for both carrier gases. The investigation of arsenic desorption revealed that compar able processes and activation energies are determined for both ambients bel ow about 950 K. However, studies at a constant AsH3 partial pressure show t hat the carrier gas has a big influence on arsenic surface coverage. This o bservation explains why the group V sources are exploited to a higher degre e in a nitrogen ambient [H. Hardtdegen, Electrochem. Sec. Proc. 96 (2) (199 6) 49; H. Hardtdegen, P. Giannoules, III-Vs Rev. 8 (3) (1995) 34]. (C) 1998 Elsevier Science B.V. All rights reserved.