The fabrication of GaAs Cu- and Al-metalized high electron mobility transistors

Authors: Erofeev E. V., Kazimirov A. I.

Annotation: The Au free fully Cu-metalized GaAs pHEMT using developed Pd/Ni/Ge/Mo/Cu based ohmic contacts and Ti/Mo/Cu 150 nm T-shape gate has been successfully fabricated for the high-frequency applications. The fabricated Cu-metalized pHEMT has a maximum drain current of 240 mA/mm, off-state gate-drain breakdown of 7 V and a transconductance peak of 440 mS/mm at Uds = 1,5 V. The maximum stable gain value was about 18,8 dB at frequency 10 GHz. The current gain cut-off frequency of the copper metalized device is about 100 GHz at Uds = 1,5 V. The Au free fully Al-metalized GaAs pHEMT using developed Pd/Ge/Al based ohmic contacts and Ti/Al 150 nm T-shape gate has been successfully fabricated for the high-frequency applications. The fabricated Almetalized pHEMT has a maximum drain current of 320 mA/mm, off-state gate-drain breakdown of 7 V and a transconductance peak of 400 mS/mm at UDS = 2 V. The maximum stable gain value was about 17,3 dB at frequency 10 GHz. The current gain cut-off frequency of the copper metalized device is about 80 GHz at Uds = 2 V.

Keywords: gaas, phemt, ohmic contacts, t-shape gate, copper, aluminium