This work presents a HEMT test structure technology which is developed for fast on-wafer characterization of 150mm epitaxial GaN-on-Si material. The test structures allow for extraction of key device and GaN-based material parameter. Information on wafer homogeneity can be obtained via wafer maps. This technology is suitable and essential to evaluate different MOCVD growth conditions on device properties in short time and, hence, significantly accelerates the growth development towards the desired material quality for GaN-based high power electronic products.