TY - JOUR A1 - Österle, Werner A1 - Nebauer, E. A1 - Hilsenbeck, J. A1 - Würfl, J. A1 - Klein, A. T1 - XTEM and TFXRD investigations of ohmic Ti/Al/Ti/Au/WSiN contacts on AlGaN/GaN HFET layer systems N2 - The microstructural features of the high-temperature-stable ohmic contact system Ti/Al/Ti/Au/WSiN on AlGaN/GaN were investigated using analytical transmission electron microscopy and thin film x-ray diffraction. For two typical rapid thermal annealing steps at 750 °C (non-ohmic behaviour) and 850 °C (ohmic behaviour) the intermetallic phases at the metal-semiconductor interface are presented. Increased annealing leads to the transformation of an Al2Au-AlAuTi phase mixture to a mixture of Al2Au-Al3Au8 phases and the formation of Ti-Al-nitride layers at the interfaces. In light of these results the electrical contact properties are discussed. PY - 2002 U6 - https://doi.org/10.1088/0268-1242/17/3/312 SN - 0268-1242 SN - 1361-6641 VL - 17 IS - 3 SP - 249 EP - 254 PB - IOP Publ. CY - Bristol AN - OPUS4-1380 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Würfl, J. A1 - Hilsenbeck, J. A1 - Nebauer, E. A1 - Tränkle, G. A1 - Obloh, H. A1 - Österle, Werner T1 - Reliability of AIGaN/GaN HFETs comprising refractory ohmic and Schottky contacts N2 - Recent progress in the development of A1GaN/GaN heterostructure field effect transistors (HFETs) Shows the great potential towards high temperature / high power electronics. Nevertheless investigations on reliability properties of GaN-based devices are still at the beginning. The frequently used Ti/A1 based ohmic and Pt based Schottky contacts suffer from strong Degradation after aging at elevated temperatures. Therefore new contact systems have to be employed. Concerning the source and drain metallization we used an amorphous WSiN barrier layer as applied for GaAs on top of the Ti/Al-based ohmic contact. This technique significantly reduces the in-diffusion of the Au-containing overlayer, furthermore the barrier layer guaranties smooth contact morphology after RTA and aging, respectively. For the Schottky metallization the Ir/Au system was used. Reliability studies performed on HFET devices containing refractory Ti/A1/Ti/Au/WSiN ohmic and Ir/Au Schottky contacts demonstrate stable conditions during 120h aging at 500°C. KW - Semiconductor KW - Reliability KW - Contact resistance KW - Heterostructure field effect transistor PY - 2000 SN - 0026-2714 VL - 40 SP - 1689 EP - 1693 PB - Elsevier AN - OPUS4-38541 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nebauer, E. A1 - Österle, Werner A1 - Hilsenbeck, J. A1 - Würfl, J. A1 - Klein, A. T1 - XTEM and TFXRD investigations of ohmic Ti/Al/Ti/Au/WSiN contacts on AlGaN/GaN HFET layer systems N2 - The microstructural features of the high-temperature-stable ohmic contact system Ti/Al/Ti/Au/WSiN on AlGaN/GaN were investigated using analytical transmission electron microscopy and thin film x-ray diffraction. For two typical rapid thermal annealing steps at 750 ◦C (non-ohmic behaviour) and 850 ◦C (ohmic behaviour) the intermetallic phases at the metal–semiconductor interface are presented. Increased annealing leads to the transformation of an Al2Au-AlAuTi phase mixture to a mixture of Al2Au-Al3Au8 phases and the formation of Ti-Al-nitride layers at the interfaces. In light of these results the electrical contact properties are discussed. KW - Ohmic contact KW - WSiN diffusion barrier KW - Rapid thermal annealing KW - Intermetallic phases KW - AlGaN/GaN heterostructure PY - 2002 SN - 0268-1242 VL - 17 SP - 249 EP - 254 PB - IOP Publishing Ltd AN - OPUS4-38543 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -