Open AccessEffect of different ohmic contact pattern on GaN HEMT electrical properties
Author(s) -
Yongwei Zhu,
Weiwei Cao,
Chen Xu,
Yong Deng,
Deshu Zou
Publication year - 2014
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.63.117302
Subject(s) - ohmic contact , materials science , high electron mobility transistor , transconductance , annealing (glass) , optoelectronics , contact resistance , transistor , electrode , composite material , voltage , electrical engineering , layer (electronics) , chemistry , engineering
In this paper, the AlGaN/GaN HEMT (high electron mobility transistors) with different ohmic contact structures are fabricated, and the effect of different ohmic contact pattern on GaN HEMT electrical properties is studied. A conventional ohmic contact electrode structure and a new ohmic contact structure with a contact hole are fabricated and subjected to rapid thermal annealing (RTA) in flowing N2. After different structured AlGaN/GaN HEMTs are annealed at 750 ℃ for 30 seconds, in HEMTs with a conventional structure ohmic contact still does not form while in the device with ohmic contact holes a good ohmic contact is already formed. Then the surface morphology of different multilayer electrode structures is measured. Comparing Ti/Al/Ti/Au with Ti/Al/Ni/Au, we can conclude that the structure Ti/Al/Ni/Au has a more smooth surface after annealing. After testing the HEMT devices with different structures, higher transconductance and saturation current are found for the devices with ohmic contact holes. But a serious current collapse phenomenon has been observed when the gate voltage is set between 0.5 V and 2 V.