Browsing by Author "Desmaris, Vincent"

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Oxygen ion implantation isolation planar process for AlGaN/GaN HEMTs
(2007-06-01)
Shiu, Jin-Yu
;
Huang, Jui-Chien
;
Desmaris, Vincent
;
Chang, Chia-Ta
;
Lu, Chung-Yu
A multienergy oxygen ion implantation process was demonstrated to be compatible With the processing of high-power microwave AlGaN/GaN high electron mobility transistors (HEMTs). HEMTs that are isolated by this process exhibited gate-lag- and drain-lag-free operation; A maximum output power density of 5.3 W/mm at V-gs = -4 V and V-ds = 50 V and a maximum power added efficiency of 51.5% at V-gs = -4 V and V-ds = 30 V at 3 GHz were demonstrated on HEMTs without field plates on sapphire substrate. This isolation process results in planar HEMTs, circumventing potential problems with enhanced gate leakage due to the gate contacting the 2-D electron gas at the mesa sidewall.
Transmission electron microscopy assessment of the Si enhancement of Ti/Al/Ni/Au Ohmic contacts to undoped AIGaN/GaN heterostructures
(2006-08-01)
Desmaris, Vincent
;
Shiu, Jin-Yu
;
Lu, Chung-Yu
;
Rorsman, Niklas
;
Zirath, Herbert
The microstructure of Si/Ti/Al/Ni/Au was investigated using transmission electron microscopy and energy dispersive x-ray spectroscopy. The dependence of the contact resistance on the silicon layer thickness and the temperature was correlated to the microstructure of the alloyed contacts. The enhancement of the contact resistance by inserting a 30 angstrom thick Si layer under the Ti/Al/Ni/Au metallization was attributed to diffusion of the contact into the AlGaN layer. Increasing the Si thickness and or the temperature resulted in the formation of Gold (Au)-based silicides, which prevent the formation of low interfacial TiN or AlN layers. (c) 2006 American Institute of Physics.