Micro and nano analysis of 0.2 Ω mm Ti/Al/Ni/Au ohmic contact to AlGaN/GaN

As GaN technology continues to gain popularity, it is necessary to control the ohmic contact properties and to improve device consistency across the whole wafer. In this paper, we use a range of submicron characterization tools to understand the conduction mechanisms through the AlGaN/GaN ohmic contact. Our results suggest that there is a direct path for electron flow between the two dimensional electron gas and the contact pad. The estimated area of these highly conductive pillars is around 5% of the total contact area.

[1]  Horst H. Berger,et al.  Models for contacts to planar devices , 1972 .

[2]  Marc Porti,et al.  Conductivity and Charge Trapping After Electrical Stress in Amorphous and Polycrystalline $\hbox{Al}_{2}\hbox{O}_{3}\hbox{-Based}$ Devices Studied With AFM-Related Techniques , 2011, IEEE Transactions on Nanotechnology.

[3]  G. Ng,et al.  Temperature dependence of Ohmic contact characteristics in AlGaN/GaN high electron mobility transistors from −50 to 200 °C , 2009 .

[4]  R. A. Davies,et al.  Correlation of contact resistance with microstructure for Au/Ni/Al/Ti/AlGaN/GaN ohmic contacts using transmission electron microscopy , 2001 .

[5]  Ilesanmi Adesida,et al.  Formation mechanism of Ohmic contacts on AlGaN∕GaN heterostructure: Electrical and microstructural characterizations , 2008 .

[6]  Ilesanmi Adesida,et al.  Thermally-stable low-resistance Ti/Al/Mo/Au multilayer ohmic contacts on n–GaN , 2002 .

[7]  Xiaosen Liu,et al.  GaN smart power IC technology , 2010 .

[8]  A. Alberti,et al.  Microstructure and current transport in Ti/Al/Ni/Au ohmic contacts to n-type AlGaN epilayers grown on Si(111) , 2006 .

[9]  Christian Dua,et al.  Testing the Temperature Limits of GaN-Based HEMT Devices , 2010, IEEE Transactions on Device and Materials Reliability.

[10]  Amador Pérez-Tomás,et al.  Temperature behavior and modeling of ohmic contacts to Si+ implanted n-type GaN , 2011, Microelectron. Reliab..

[11]  D. Théron,et al.  Comparison between TiAl and TiAlNiAu ohmic contacts to n-type GaN , 2000 .

[12]  Baoshun Zhang,et al.  Analysis of surface roughness in Ti/Al/Ni/Au Ohmic contact to AlGaN/GaN high electron mobility transistors , 2010 .

[13]  R. Vispute,et al.  Electrical, thermal, and microstructural characteristics of Ti/Al/Ti/Au multilayer Ohmic contacts to n-type GaN , 2003 .

[14]  J. Kwak,et al.  Temperature-dependent contact resistivity of the nonalloyed ohmic contacts to p-GaN , 2004 .

[15]  A. Yu,et al.  Electron tunneling and contact resistance of metal-silicon contact barriers , 1970 .

[16]  J. Millan,et al.  GaN transistor characteristics at elevated temperatures , 2009 .

[17]  A. Klein,et al.  XTEM and TFXRD investigations of ohmic Ti/Al/Ti/Au/WSiN contacts on AlGaN/GaN HFET layer systems , 2002 .

[18]  Transport properties of the advancing interface ohmic contact to AlGaN/GaN heterostructures , 2002 .

[19]  E. B. Kaminsky,et al.  Structural properties of alloyed Ti/Al/Ti/Au and Ti/Al/Mo/Au ohmic contacts to AlGaN/GaN , 2006 .

[20]  G. Tränkle,et al.  Mechanism of ohmic contact formation in AlGaN/GaN high electron mobility transistors , 2006 .

[21]  Fabrizio Roccaforte,et al.  Temperature dependence of the specific resistance in Ti∕Al∕Ni∕Au contacts on n-type GaN , 2006 .