Anatomy-performance correlation in Ti-based contact metallizations on AlGaN/GaN heterostructures

A comprehensive study of the electrical and surface microstructural characteristics of Ti∕Au, Ti∕Al∕Au, Ti∕Mo∕Au, and Ti∕Al∕metal∕Au schemes, where metal is Ir, Mo, Nb, Pt, Ni, Ta, and Ti, has been carried out to determine the role of constituent components of multilayer contact metallizations on Ohmic contact formation on AlGaN∕GaN heterostructures. Attempts have been made to elucidate the anatomy (composition–structure) performance correlation in these schemes. Evidences have been obtained for the necessity of the Al and metal barrier layer as well as an optimal amount of Ti for achieving low-resistance Ohmic contact formation. A strong dependence of electrical properties and intermetallic interactions on the type of metal barrier layer used was found. Scanning electron microscopy characterization, coupled with energy dispersive x-ray spectroscopy, has shown evidence for alloy aggregation, metal layer fragmentation, Al–Au solid solution formation, and possible Au and/or Al reaction with metal layer. Res...

[1]  H. Gong,et al.  Electrical characterization and metallurgical analysis of Pd-containing multilayer contacts on GaN , 2001 .

[2]  Yuji Ando,et al.  Low-contact-resistance and smooth-surface Ti∕Al∕Nb∕Au ohmic electrode on AlGaN∕GaN heterostructure , 2004 .

[3]  Fritz Aldinger,et al.  Ternary Alloys: A Comprehensive Compendium of Evaluated Constitutional Data and Phase Diagrams , 1989 .

[4]  Ilesanmi Adesida,et al.  Dislocation-induced nonuniform interfacial reactions of Ti∕Al∕Mo∕Au ohmic contacts on AlGaN∕GaN heterostructure , 2005 .

[5]  I. Adesida,et al.  Ohmic contact formation mechanism of Ta∕Al∕Mo∕Au and Ti∕Al∕Mo∕Au metallizations on AlGaN∕GaN HEMTs , 2005 .

[6]  Electric and Morphology Studies of Ohmic Contacts on AlGaN/GaN , 2000 .

[7]  Properties of Ir-based Ohmic contacts to AlGaN/GaN high electron mobility transistors , 2004 .

[8]  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 .

[9]  I. Adesida,et al.  Differences in the reaction kinetics and contact formation mechanisms of annealed Ti∕Al∕Mo∕Au Ohmic contacts on n-GaN and AlGaN∕GaN epilayers , 2007 .

[10]  F. Ren,et al.  Comparison of Ir and Ni-based Ohmic contacts for AlGaN/GaN high electron mobility transistors , 2004 .

[11]  Jenkins,et al.  Electronic structures and doping of InN, InxGa1-xN, and InxAl1-xN. , 1989, Physical review. B, Condensed matter.

[12]  A. Motayed,et al.  Low-resistance Ti/Al/Ti/Au multilayer ohmic contact to n-GaN , 2001 .

[13]  Y. Chen,et al.  An Al/sub 0.3/Ga/sub 0.7/N/GaN undoped channel heterostructure field effect transistor with F/sub max/ of 107 GHz , 1999, IEEE Electron Device Letters.

[14]  R. Davis,et al.  Low energy ion‐assisted deposition of titanium nitride ohmic contacts on alpha (6H)‐silicon carbide , 1991 .

[15]  岡本 博明,et al.  Desk handbook phase diagrams for binary alloys , 2000 .

[16]  Y. L. Chen,et al.  High performance AlGaN/GaN HEMT with improved ohmic contacts , 1998 .

[17]  F. W. Saris,et al.  Prediction of phase formation sequence and phase stability in binary metal-aluminum thin-film systems using the effective heat of formation rule , 1991 .

[18]  H. Morkoç,et al.  Microstructure of Ti/Al and Ti/Al/Ni/Au Ohmic contacts for n-GaN , 1996 .

[19]  Y. Kimura,et al.  Phase equilibria in the Ir-rich portion of the Ir–Al–X (X: Ti, Zr and Hf) ternary systems , 2005 .

[20]  V. R. Reddy,et al.  Electrical and structural properties of low-resistance Ti/Al/Re/Au ohmic contacts to n-type GaN , 2004 .

[21]  H. Morkoç,et al.  Very low resistance multilayer Ohmic contact to n‐GaN , 1996 .

[22]  S. Lau,et al.  A review of the metal–GaN contact technology , 1998 .

[23]  R. F. Karlicek,et al.  Analysis of a thin AlN interfacial layer in Ti/Al and Pd/Al ohmic contacts to n-type GaN , 1997 .

[24]  I. Adesida,et al.  The role of barrier layer on Ohmic performance of Ti∕Al-based contact metallizations on AlGaN∕GaN heterostructures , 2006 .

[25]  M. Khan,et al.  Study of contact formation in AlGaN/GaN heterostructures , 1997 .

[26]  Ching-Ting Lee,et al.  Long-term thermal stability of Ti/Al/Pt/Au Ohmic contacts to n-type GaN , 2000 .

[27]  Z. Qin,et al.  Study of Ti/Au, Ti/Al/Au, and Ti/Al/Ni/Au ohmic contacts to n-GaN , 2004 .