Pseudomorphic and metamorphic HEMT-technologies for industrial W-band low-noise and power applications

The W-band ranging from 75 to 110 GHz marks a frequency window of low atmospheric absorption with the minimum at 94 GHz, suited for high bandwidth data transmission and radar applications. In this work, pseudomorphic and metamorphic HEMT-technologies have been developed compatible with the 4"-fabrication environment of United Monolithic Semiconductors. Besides the progression of the pHEMT-technology by down scaling of the gate length to 80 nm, two single recess and one double recess metamorphic HEMT-technology on GaAs substrate have been developed to improve the RF-gain of the active device. Device processing is discussed with respect to production worthiness starting with the epitaxy layer sequence, ohmic contact formation, the T-gate technology, recess formation and device passivation. Based on device modelling, low-noise amplifiers and power amplifiers have been fabricated to demonstrate the transistor performance on MMIC-level including the evaluation of fabrication yield. The 80 nm pseudomorphic HEMT-technology can address the W-band regarding low-noise and power applications. Compared to the metamorphic power technologies, the pseudomorphic HEMT is less sensitive to impact ionization and provides higher output power densities up to 900 mW/mm. However, the low bandgap metamorphic technologies are the right choice to target for even higher frequencies up to 300 GHz, especially for low-noise thanks to superior small signal gain