AlGaN/GaN HEMT grown on large size silicon substrates by MOVPE capped with in-situ deposited Si3N4

{ "0" : "MCP/ART, IMEC, Kapeldreef 75, B-3001 Leuven, Belgium" , "1" : "Department of Electrical Engineering, Katholieke Universiteit Leuven, Belgium" , "2" : "Department of Physics, Katholieke Universiteit Leuven, Belgium" , "4" : "73.61.Ey" , "5" : "73.20.At" , "6" : "81.05.Ea" , "7" : "81.15.Gh" , "8" : "72.80.Ey" , "9" : "85.30.Tv" , "10" : "A1. Characterization" , "11" : "A3. Metal organic vapor phase epitaxy" , "12" : "B1. Nitrides" , "13" : "B3. High electron mobility transistors"}
Journal of Crystal Growth (Impact Factor: 1.69). 01/2007; DOI: 10.1016/j.jcrysgro.2006.10.185

ABSTRACT AlGaN/GaN high electron mobility transistors (HEMTs) have been grown on 4 and 6 in Si(1 1 1) substrates by metal organic vapor phase epitaxy (MOVPE). A record sheet resistance of 256 Ω/□ has been measured by contactless eddy current mapping on 4 in silicon substrates. The wafer also shows an excellent uniformity and the standard variation is 3.6 Ω/□ over the whole wafer. These values were confirmed by Hall–Van der Pauw measurements. In the 2DEG at the AlGaN/GaN interface, the electron mobility is in the range of 1500–1800 cm2/Vs and the electron density is between 1.3×1013 and 1.7×1013 cm−2. The key step in obtaining these results is an in-situ deposited Si3N4 passivation layer. This in-situ Si3N4, deposited directly after AlGaN top layer growth in the MOVPE reactor chamber, not only prevents the stress relaxation in AlGaN/GaN hetero-structures but also passivates the surface states of the AlGaN cap layer. HEMT transistors have been processed on the epitaxial structures and the maximum source–drain current density is 1.1 A/mm for a gate-source voltage of 2 V. The current collapse is minimized thanks to in-situ Si3N4. First results on AlGaN/GaN structures grown on 6 in Si(1 1 1) are also presented.