Traps and Defects in AlGaN-GaN High Electron Mobility Transistors on Semi-Insulating SiC Substrates

2009 ◽  
Vol 1202 ◽  
Author(s):  
Yongkun Sin ◽  
Erica Deionno ◽  
Brendan Foran ◽  
Nathan Presser
Keyword(s):  
Hall Mobility ◽  
Electron Mobility ◽  
Schottky Diodes ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Plan View ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Algan Barrier ◽  
Sheet Density

AbstractHigh electron mobility transistors (HEMTs) based on AlGaN-GaN hetero-structures are promising for high power, high speed, and high temperature operation. Especially, AlGaN-GaN HEMTs grown on semi-insulating (SI) SiC substrates are the most promising for both military and commercial applications. High performance characteristics from these devices are possible in part due to the presence of high two-dimensional electron gas charge sheet density maintaining a high Hall mobility at the AlGaN barrier-GaN buffer hetero-interface and in part due to high thermal conductivity of the SiC substrates. However, long-term reliability of these devices still remains a major concern because of the large number of traps and defects present both in the bulk as well as at the surface leading to undesirable characteristics including current collapse. We report on the study of traps and defects in two MOCVD-grown structures: Al0.27Ga0.73N HEMTs on SI SiC substrates and Al0.27Ga0.73N Schottky diodes on conducting SiC substrates. Our HEMT structures consisting of undoped AlGaN barrier and GaN buffer layers grown on an AlN nucleation layer show a charge sheet density of ∼1013/cm2 and a Hall mobility of ∼1500cm2/V·sec. Deep level transient spectroscopy (DLTS) was employed to study traps in AlGaN Schottky diodes and HEMTs fabricated with different Schottky contacts consisting of Pt/Au and Ni/Au. Focused ion beam was employed to prepare both cross-sectional and plan view TEM samples for defect analysis using a high resolution TEM.

A Study of Defects and Surface Properties in AlGaN/GaN High Electron Mobility Transistors (HEMTs) Grown by MOCVD on Semi-Insulating SiC Substrates

2006 ◽  
Vol 955 ◽  
Author(s):  
Yongkun Sin ◽  
Hyun I Kim ◽  
Paul Adams ◽  
Gary Stupian
Keyword(s):  
Surface Properties ◽  
Hall Mobility ◽  
Electron Mobility ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Plan View ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Algan Barrier ◽  
Sheet Density

ABSTRACTAlGaN/GaN HEMTs (High Electron Mobility Transistors) grown on semi-insulating (SI) SiC substrates are very promising for high power, high speed, and high temperature operation with great potential for both military and commercial applications. These high performance characteristics are possible due to presence of high two-dimensional electron gas (2 DEG) charge sheet density maintaining a high Hall mobility at the AlGaN barrier/GaN buffer hetero-interface. However, reliability of AlGaN HEMTs still remains a major concern because of the large number of defects and traps present both in the bulk as well as at the surface leading to current collapse. We report on the study of defects and surface properties in MOCVD-grown Al0.27Ga0.73N HEMT structures on SI SiC substrates. Our HEMT structures consist of a 25nm thick undoped AlGaN barrier layer and a 3μm thick undoped GaN buffer layer grown on a 100nm thick AlN nucleation layer. Hall measurements showed a charge sheet density of ∼1013/cm2 and a Hall mobility of ∼1500cm2/V·sec. Both cross-sectional and plan view TEMs were employed to study defects in the heterostructures and XPS (X-ray Photoelectron Spectroscopy) and AES (Auger Electron Spectroscopy) employed to study surface properties in both GaN and AlGaN layers. DC characterization results from AlGaN Schottky diodes with Pt/Au Schottky contacts are also reported along with results from AlGaN/GaN HEMT devices.

scholarly journals Development of AlGaN/GaN/SiC high-electron-mobility transistors for THz detection

2018 ◽  
Vol 58 (2) ◽  
Author(s):  
Vytautas Jakštas ◽  
Justinas Jorudas ◽  
Vytautas Janonis ◽  
Linas Minkevičius ◽  
Irmantas Kašalynas ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Schottky Diodes ◽  
Electronic Devices ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
High Electron Mobility ◽  
Gan Hemt ◽  
Electron Mobility Transistors ◽  
Steady Current ◽  
Improved Performance

This paper reports on the AlGaN/GaN Schottky diodes (SDs) and high-electron-mobility transistors (HEMTs) grown on a semi-insulating SiC substrate. The electronic devices demonstrate an improved performance in comparison with the ones processed on a sapphire substrate. Both the SDs and HEMTs show much smaller leakage current density and a higher ION/IOFF ratio, reaching values down to 3.0±1.2 mA/cm2 and up to 70 dB under the reverse electric field of 340 kV/cm, respectively. The higher thermal conductivity of the SiC substrate leads to the increase of steady current and transconductance, and better thermal management of the HEMT devices. In addition, a successful detection of terahertz (THz) waves with the AlGaN/GaN HEMT is demonstrated at room temperature. These results open further routes for the optimization of THz designs which may result in development of novel plasmonic THz devices.

AlGaN/GaN High Electron Mobility Transistors on Si/SiO2/poly-SiC Substrates

2006 ◽  
Vol 955 ◽  
Author(s):  
Travis Anderson ◽  
Fan Ren ◽  
Lars Voss ◽  
Mark Hlad ◽  
Brent P Gila ◽  
...  
Keyword(s):  
Electron Mobility ◽  
High Electron Mobility Transistors ◽  
Parameter Extraction ◽  
High Electron ◽  
High Electron Mobility ◽  
Drain Spacing ◽  
Electron Mobility Transistors ◽  
Algan Barrier ◽  
Rf Performance ◽  
Spacing Parameter

ABSTRACTThe dc and rf performance of AlGaN/GaN High Electron Mobility Transistors (HEMTs) grown by Molecular Beam Epitaxy on Si-on-poly (SopSiC) substrates is reported. The HEMT structure incorporated a 7 period GaN/AlN superlattice between the AlGaN barrier and GaN channel for improved carrier confinement. The knee voltage of devices with 2 μm gate-drain spacing was 2.12 V and increased to 3 V at 8 μm spacing. The maximum frequency of oscillation, fMAX, was ∼40 GHz for devices with 0.5 μm gate length and 2 μm gate-drain spacing. Parameter extraction from the measured rf characteristics showed a maximum intrinsic transconductance of 143 mS.mm−1.

Schottky diodes and high electron mobility transistors of 2DEG AlGaN/GaN structures on sapphire substrate

2015 ◽  
Vol 54 (4) ◽  
Author(s):  
Vytautas Jakštas ◽  
Irmantas Kašalynas ◽  
Irena Šimkienė ◽  
Viktorija Strazdienė ◽  
Pawel Prystawko ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Electron Mobility ◽  
Schottky Diodes ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
High Electron Mobility ◽  
Electron Mobility Transistors

scholarly journals The impact of dislocations on AlGaN/GaN Schottky diodes and on gate failure of high electron mobility transistors

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sven Besendörfer ◽  
Elke Meissner ◽  
Farid Medjdoub ◽  
Joff Derluyn ◽  
Jochen Friedrich ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Reverse Bias ◽  
Schottky Diodes ◽  
Forward Bias ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Conductive Atomic Force Microscopy ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
The Impact

Abstract GaN epitaxially grown on Si is a material for power electronics that intrinsically shows a high density of dislocations. We show by Conductive Atomic Force Microscopy (C-AFM) and Defect Selective Etching that even for materials with similar total dislocation densities substantially different subsets of dislocations with screw component act as current leakage paths within the AlGaN barrier under forward bias. Potential reasons are discussed and it will be directly shown by an innovative experiment that current voltage forward characteristics of AlGaN/GaN Schottky diodes shift to lower absolute voltages when such dislocations are present within the device. A local lowering of the Schottky barrier height around conductive dislocations is identified and impurity segregation is assumed as responsible root cause. While dislocation related leakage current under low reverse bias could not be resolved, breakdown of AlGaN/GaN Schottky diodes under high reverse bias correlates well with observed conductive dislocations as measured by C-AFM. If such dislocations are located near the drain side of the gate edge, failure of the gate in terms of breakdown or formation of percolation paths is observed for AlGaN/GaN high electron mobility transistors.

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