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 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.

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this letter, we present a novel approach to enhance the breakdown voltage ( V <sub>BD</sub>) for AlGaN/GaN/AlGaN double-heterostructure FETs (DHFETs), grown by metal-organic chemical vapor deposition on Si (111) substrates through a silicon-substrate-removal and a layer-transfer process. Before removing the Si substrate, both buffer isolation test structures and DHFET devices showed a saturation of V <sub>BD</sub> due to the electrical breakdown through the Si substrate. We observed a V <sub>BD</sub> saturation of 500 V for isolation gaps larger than 6 μm . After Si removal, we measured a V <sub>BD</sub> enhancement of the AlGaN buffer to 1100 V for buffer isolation structures with an isolation gap of 12 μm. The DHFET devices with a gate-drain ( L <sub>GD</sub>) distance of 15 μm have a V<sub>BD</sub> > 1100 V compared with ~300 V for devices with Si substrate. Moreover, from Hall measurements, we conclude that the substrate-removal and layer-transfer processes have no impact on the 2-D electron gas channel properties.
    IEEE Electron Device Letters 09/2010; · 2.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The properties of a new class of electromechanical resonators based on GaN are presented. By using the two-dimensional electron gas (2-DEG) present at the AlGaN/GaN interface and the piezoelectric properties of this heterostructure, we use the R-HEMT (Resonant High Electron Mobility Transistor) as an active piezoelectric transducer up to 5MHz. In addition to the amplification effect of piezoelectric detection, we show that the active piezoelectric transduction has a strong dependence with the channel mobility that is controlled by a top gate. This allows to envision highly tunable sensors with co-integrated HEMT electronics.
    Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report fabrication of AlGaN/GaN high electron mobility transistor (HEMT) with improved DC, high frequency and microwave power performances by employing a two-step passivation approach. A pretreated AlGaN surface is provided by dry etching n+-GaN cap layer and RTA annealing ohmic contacts right before Si3N4 passivant is deposited. No additional process step is associated with the surface preparation for the passivation process. Pulsed I-V characteristics show that the proposed passivation process successfully eliminates trapping effect at Si3N4 and AlGaN interface and is considered to be the important factor for the performance enhancement. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1614–1619, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25266
    Microwave and Optical Technology Letters 04/2010; 52(7):1614 - 1619. · 0.59 Impact Factor