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 GaAs in the temperature range between 670 and 990 K by means of reflectance anisotropy 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 comparable processes and activation energies are determined for both ambients below about 950 K. However, studies at a constant AsH(3) partial pressure show that the carrier gas has a big influence on arsenic surface coverage. This observation explains why the group V sources are exploited to a higher degree in a nitrogen ambient [H. Hardtdegen, Electrochem. Sec. Proc. 96 (2) (1996) 49; H. Hardtdegen, P. Giannoules, III-Vs Rev. 8 (3) (1995) 34]. (C) 1998 Elsevier Science B.V. All rights reserved.