We employed a newly developed wafer-selective curvature, reflectance and temperature sensor (EpiCurveTT (R)) in an AIX2600HT Planetary Reactor (R). Growth of GaN on sapphire as well as AlGaN and InGaN heterostructures with different material compositions were monitored in real time. During growth of a laser-diode text structure the impact of water curvature on wavelength uniformity across the water is demonstrated. Here, the known drastic dependence of indium incorporation on growth temperature requires a uniform substrate surface temperature and therefore a flat wafer during growth of the MQW region. Wafer bowing depending on substrate properties, growth temperature and the insertion of a strain-compensating interlayer is carefully examined to optimize the growth procedure. (c) 2006 Elsevier B.V. All rights reserved.