Comparison of binary and ternary growth over trenches using MOVPE

The MOVPE growth of Al0.3Ga0.7As over trenches is compared to the growth of its binary components GaAs and AlAs. The growth rates for GaAs, AlAs and A lGaAs on planar (1 0 0), (3 1 1)A and (3 1 1)B substrates are independent o f orientation and the AlGaAs growth rate and composition can be described b y the sum of the two binaries. For growth over trenches with {3 1 1}-sidewa lls the growth rate and the composition on the sidewalls are different comp ared to (100) due to interplay of the adjacent facets. The AlAs growth rate is nearly the same on the sidewalls and the planar regions indicating that Al is incorporated without extensive surface diffusion. For growth tempera tures above 660 degrees C the GaAs growth rate on the sidewalls is enhanced indicating strong Ga diffusion from (1 0 0) to the sidewalls. From these t wo binary growth rates the Al0.3Ga0.7As growth rate and composition is calc ulated and compared to the measured values. On the sidewalls the measured A lGaAs growth rate is lower and the Al content is higher than expected from the binary results. (C) 2000 Elsevier Science B.V. All rights reserved.