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We report for the first time the successful epitaxial growth and processing of high-performance metamorphic high electron mobility transistors (HEMTs) on Ge substrates, with a transconductance of 700 mS/mm and a saturation channel current of 650 mA/mm. To reduce parasitic capacitances due to the conductive substrate, a dry etch method based on CF4 and O2 reactive ion etching (RIE) is developed for selective substrate removal. Devices with 0.2 μm gate length display an increase of the extrinsic cut-off frequency fT from 45 GHz before, to 75 GHz after substrate removal, whereas the maximum oscillation frequency fmax increases from 68 GHz to 95 GHz. Based on this excellent rf performance level, in combination with the highly selective thinning process, we think that Ge as a sacrificial substrate is a promising candidate for the integration of thinned individual HEMTs with passive circuitry on low-cost substrates. This could result in low-cost advanced hybrid systems for mass-market millimeter wave applications.