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: 1.7). 01/2007; 298:822-825. DOI: 10.1016/j.jcrysgro.2006.10.185


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.

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    • "A. Device fabrication The AlGaN/GaN layer stack was grown by metal-organicvapor-phase epitaxy on highly resistive (ρ>5000 Ωcm) 4 inch Si (111) substrates [5]. The layer stack typically consists of an AlN nucleation layer, AlGaN intermediate layers compensating the mismatch of thermal expansion coefficients and lattice constants, followed by a 1 µm GaN buffer layer and a 22 nm Al 0.3 Ga 0.7 N layer which was capped after growth with an in-situ deposited 3.5 nm thick Si 3 N 4 layer. "
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    ABSTRACT: Low-ppb room temperature NO2 detection is demonstrated for the first time using ultra-thin AlGaN/GaN heterostructures fabricated on silicon substrates. AlGaN/GaN shows great promise as a generic platform for (bio-)chemical sensing because of its robustness and intrinsic sensitivity to surface charges and dipoles. Here, we employ the two-dimensional electron gas (2DEG) formed at the interface of the AlGaN/GaN heterostructure for the monitoring of low-ppb NO2 concentrations in ambient air. We find that in the presence of humidity, the interaction of NO2 with the open gate area reversibly changes 2DEG conductivity. The dynamic range of these structures can be tuned to that of interest for air quality monitoring (0-100 ppb) by precisely back etching the open gate areas. A slope-based detection scheme in combination with periodic heating-induced gas desorption enables continuous air quality (NO2) monitoring.
    Full-text · Article · Oct 2012 · IEEE Sensors Journal
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    • "Having a high bandgap and a very good chemical inertness, GaN is also able to withstand high electric fields. More recently, the fact that GaN has become available on silicon substrates with large diameters [1] makes it very interesting for high volume market such as power conversion, which in turn has triggered original device research and cost reduction [2]. However up to now little work has been done with monocrystalline III-N compounds about MEMS in comparison of the field of optoelectronics. "
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    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.
    Full-text · Conference Paper · Feb 2011
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    ABSTRACT: The effects of rapid thermal annealing on the optical and the electrical properties in GaN epilayers grown on Si substrates were investigated by using cathodoluminescence (CL) and Hall effect measurements. From the two-dimensional CL image measurements, the distribution of defects embedded in the films was investigated before and after rapid thermal annealing. The penetration depth dependence of the CL spectrum demonstrated that the defect density become large in the deeper region away from the GaN surface.
    Full-text · Article · May 2012 · Journal- Korean Physical Society
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