scholarly journals Quantitative analysis of electrically active defects in Au/AlGaN/GaN HEMTs structure using capacitance–frequency and DLTS measurements

2021 ◽  
Author(s):  
Nargis Bano ◽  
Ijaz Hussain ◽  
Eman Al-Ghamdi ◽  
M. Saeed Ahmad
Keyword(s):  
Time Constant ◽  
Point Defects ◽  
Deep Level ◽  
Surface States ◽  
High Electron Mobility Transistor ◽  
Interface States ◽  
Electron Trap ◽  
Nitrogen Vacancy ◽  
High Electron ◽  
Trap States

Abstract Electrical trap states in the AlGaN-based high-electron-mobility transistor (HEMT) structures limit the performances of devices. In this study, we present a comprehensive study of the electrical trap states in AlGaN/GaN HEMT structures and examine their influence on the device performance. We performed capacitance–frequency and conductance–frequency measurements to determine the time constant and the density of the interface states. The density of the interface states was calculated to be 2 × 1010 cm−2 eV−1, and the time constant of the interface states was 1 μs. Deep-level transient spectroscopy showed the presence of one electron trap E1 (negative peak) and three hole-like traps P1, P2, and P3 (positive peaks). The thermal activation energies for E1, P1, P2, and P3 traps were calculated to be 1.19, 0.64, 0.95, and 1.32 eV, respectively. The electron trap E1 and the hole-like traps P1, P2 and P3 were observed to originate from the point defects or their complexes in the material. The hole-like traps reflected the changes created in the population of the surface states owing to the capture of the surface states; these traps originated from the point defects related to the nitrogen vacancy.

scholarly journals Identification of Buffer and Surface Traps in Fe-Doped AlGaN/GaN HEMTs Using Y21 Frequency Dispersion Properties

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3096
Author(s):  
P. Vigneshwara Raja ◽  
Nandha Kumar Subramani ◽  
Florent Gaillard ◽  
Mohamed Bouslama ◽  
Raphaël Sommet ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Drain Current ◽  
Surface Region ◽  
Electron Trap ◽  
High Electron ◽  
Trap States ◽  
Dispersion Properties ◽  
Donor States ◽  
Surface Donor

The buffer and surface trapping effects on low-frequency (LF) Y-parameters of Fe-doped AlGaN/GaN high-electron mobility transistors (HEMTs) are analyzed through experimental and simulation studies. The drain current transient (DCT) characterization is also carried out to complement the trapping investigation. The Y22 and DCT measurements reveal the presence of an electron trap at 0.45–0.5 eV in the HEMT structure. On the other hand, two electron trap states at 0.2 eV and 0.45 eV are identified from the LF Y21 dispersion properties of the same device. The Y-parameter simulations are performed in Sentaurus TCAD in order to detect the spatial location of the traps. As an effective approach, physics-based TCAD models are calibrated by matching the simulated I-V with the measured DC data. The effect of surface donor energy level and trap density on the two-dimensional electron gas (2DEG) density is examined. The validated Y21 simulation results indicate the existence of both acceptor-like traps at EC –0.45 eV in the GaN buffer and surface donor states at EC –0.2 eV in the GaN/nitride interface. Thus, it is shown that LF Y21 characteristics could help in differentiating the defects present in the buffer and surface region, while the DCT and Y22 are mostly sensitive to the buffer traps.

Photoreflectance Probing of Below Gap States in Gan/Algan High Electron Mobility Transitor Structures

2002 ◽  
Vol 743 ◽  
Author(s):  
D. K. Gaskill ◽  
O. J. Glembocki ◽  
B. Peres ◽  
R. Henry ◽  
D. Koleske ◽  
...  
Keyword(s):  
Electron Mobility ◽  
High Electron Mobility Transistor ◽  
Phase Lag ◽  
High Electron ◽  
Trap States ◽  
High Electron Mobility ◽  
Gap States ◽  
Impedence Spectroscopy

ABSTRACTOptical Impedence Spectroscopy of GaN/AlGaN high electron mobility transistor structures (HEMTs) using photoreflectance exhibit a photoreflectance lags – the component of the modulated reflectance out of phase with the chopper – ranging from 0.1 to 0.5. Photoreflectance was performed using below gap pumping on various samples. Samples that do exhibit appreciable photoreflectance lag for above gap pumping show significantly enhanced photoreflectance signals for below gap pumping. Yet, samples that do not exhibit appreciable photoreflectance lag for above gap pumping do not exhibit a signal for below gap pumping. This implies that the photoreflectance phase lag is due to mid-gap trap states. At least 2 types of traps are found, above and below about 2.5 eV. This result means that that photoreflectance can be used as a probe of HEMT device quality.

Point Defects in a Directly-Bonded Wafer, and its Comparison with the Bonded Soi Wafers

1993 ◽  
Vol 302 ◽  
Author(s):  
Akira Usami ◽  
Keisuke Kaneko ◽  
Akira Ito ◽  
Shun-ichiro Ishigami ◽  
Takao Wada
Keyword(s):  
Point Defects ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Oxide Thickness ◽  
Electron Trap ◽  
Silicon On Insulator ◽  
Trap Concentration ◽  
Active Layers ◽  
Capacitance Voltage ◽  
Transient Spectroscopy

ABSTRACT<Directly-bonded wafers were characterized using capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements. We also studied silicon on insulator (SOI) wafers with different interfacial oxide thicknesses. In the active layers of the directly bonded wafer, two dominant electron traps (Ec-0.16eV, Ec-0.24eV) were observed at 23 μμμμm from the bonded interface. Both trap densities are almost constant (about 2 × 1011cm−3) at distances larger than about 10 μm. In the substrate, the density of the shallower electron trap increases (about 8 × 1011 cm−3) within about 20 μm from the interface, while the other trap concentration is almost constant and nearly equal to that in the active layers. No trap was observed near the wafer backside. These traps were also observed in the bonded SO1 wafers. Both the trap concentrations depend on the thickness of the bonded interfacial oxide. The shallower trap concentration increases with increasing oxide thickness, and the deeper one decreases.

scholarly journals Low Gate Lag Normally-Off p-GaN/AlGaN/GaN High Electron Mobility Transistor with Zirconium Gate Metal

Crystals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 25 ◽  
Author(s):  
Chia-Hao Liu ◽  
Hsien-Chin Chiu ◽  
Chong-Rong Huang ◽  
Kuo-Jen Chang ◽  
Chih-Tien Chen ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Schottky Contact ◽  
High Mobility ◽  
High Electron Mobility Transistor ◽  
Nitrogen Vacancy ◽  
High Electron ◽  
High Electron Mobility ◽  
Switching Power ◽  
Device Applications ◽  
The Impact

The impact of gate metal on the leakage current and breakdown voltage of normally-off p-GaN gate high-electron-mobility-transistor (HEMT) with nickel (Ni) and zirconium (Zr) metals were studied and investigated. In this study, a Zr metal as a gate contact to p-GaN/AlGaN/GaN high mobility transistor (HEMT) was first applied to improve the hole accumulation at the high gate voltage region. In addition, the ZrN interface is also beneficial for improving the Schottky barrier with low nitrogen vacancy induced traps. The features of Zr are low work function (4.05 eV) and high melting point, which are two key parameters with p-GaN Schottky contact at reversed voltage. Therefore, Zr/p-GaN interface exhibits highly potential for GaN-based switching power device applications.

Transient Current and Transient Capacitance Measurements of Defects in AlGaAs Hemts

1989 ◽  
Vol 163 ◽  
Author(s):  
R. Magno ◽  
R. Shelby
Keyword(s):  
Deep Level ◽  
High Electron Mobility Transistor ◽  
Transient Current ◽  
High Electron ◽  
Transient Source ◽  
Transient Capacitance ◽  
Accelerated Lifetime ◽  
Carrier Trap ◽  
Additional Current ◽  
Dlts Spectra

AbstractThe defects present in AlGaAs high electron mobility transistor (HEMT) devices subjected to accelerated lifetime tests have been studied by transient current, and when possible, by transient capacitance techniques. By measuring transient source-drain currents following the application of a voltage pulse to the gate it is possible to perform deep level transient spectros-copy (DLTS) experiments on HEMT devices which are too small for the conventional capacitance DLTS. The capacitance and current spectra for both stressed and unstressed HEMTs contain the AlGaAs DX defect. The current DLTS spectra for stressed devices contain an additional feature which is not found in capacitance DLTS measurements on the stressed HEMTs. This additional current DLTS feature is anomalous in that the transient has a sign which is opposite to that expected for a majority carrier trap. The absence of the new defect in the capacitance DLTS suggests that the defect is located in the channel between the gate and either the source or the drain. The current DLTS line shape of the stressed induced defect depends upon the polarity and size of the source-drain voltage.

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