Stacked layer sequences of InP-based HBT and HEMT are of interest for today's (OC-768) and tomorrows (OC-3072, 100 Gbit Ethernet) communication standards. The better low noise performance of the HEMT can be combined with the driver capability of the HBT while also a PIN-photodiode can be provided by the HBT base-collector-diode. However this results in a complex procedure for MOVPE growth process development. For a reliable fabrication of complex radio frequency (opto-)electronic circuit applications a quantitative InP process technology control is necessary starting at the level of device epilayer stacks. In this report the detailed characterization of stacked InP/(InGa)As:C HBT and InP/(InGa)As HEMT layer sequences is carried out by non-destructive X-ray analysis. Based on X-ray measurements in 004- and 002-reflection a detailed analysis of complex device layer stacks is purposed. As a result, an automatic calculation of layer parameters. e.g. thickness and composition is possible. reducing the turnaround time for the statistical process control (SPC). (C) 2002 Elsevier Science B.V. All rights reserved.