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AlGaN/GaN epitaxy and technology

: Waltereit, P.; Bronner, W.; Quay, R.; Dammann, M.; Kiefer, R.; Pletschen, W.; Müller, S.; Aidam, R.; Menner, H.; Kirste, L.; Köhler, K.; Mikulla, M.; Ambacher, O.


International journal of microwave and wireless technologies 2 (2010), No.1, pp.3-11
ISSN: 1759-0795
ISSN: 1759-0787
Journal Article
Fraunhofer IAF ()
GaN; MMIC; HEMT; PAE; reproducibility; homogeneity; reliability

We present an overview on epitaxial growth, processing technology, device performance, and reliability of our GaN high electron mobility transistors (HEMTs) manufactured on 3- and 4-in. SiC substrates. Epitaxy and processing are optimized for both performance and reliability. We use three different gate lengths, namely 500 nm for 1-6 GHz applications, 250 nm for devices between 6 and 18 GHz, and 150 nm for higher frequencies. The developed HEMTs demonstrate excellent high-voltage stability, high power performance, and large DC to RF conversion efficiencies for all gate lengths. On large gate width devices for base station applications, an output power beyond 125 W is achieved with a power added efficiency around 60% and a linear gain around 16 dB. Reliability is tested both under DC and RF conditions with supply voltage of 50 and 30 V for 500 and 250 nm gates, respectively. DC tests on HEMT devices return a drain current change of just about 10% under IDQ conditions. Under RF stress the observed change in output power density is below 0.2 dB after more than 1000 h for both gate length technologies.