Mechanism of the reverse gate leakage in AlGaN/GaN high electron mobility transistors

Karmalkar, Shreepad; Sathaiya, D. Mahaveer; Shur, M. S.

doi:10.1063/1.1579852

Cited by 121 publications

(86 citation statements)

References 8 publications

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“…This exception is thought to be due to the process variations. The fact that the extracted effective barrier height is much lower than the theoretically predicted values and very large ideality factors (> 2.4) indicates that the gate currents of fabricated AlGaN/GaN HEMTs are not dominated by the TE mechanism but other mechanisms, such as vertical tunneling [38], surface barrier thinning [39], and trap-assisted tunneling [40], etc. Thus, the barrier heights and ideality factors, which are extracted by using the TE model, are not accurate.…”

Section: Suppression Of Schottky Gate-leakage Currentmentioning

confidence: 92%

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Cai

Zhou

Lau

et al. 2006

IEEE Trans. Electron Devices

507

286

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Section: Suppression Of Schottky Gate-leakage Currentmentioning

confidence: 92%

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Cai

Zhou

Lau

et al. 2006

IEEE Trans. Electron Devices

507

286

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“…Other groups also suggested the trap-assisted tunneling model to explain the leakage mechanism in the reverse bias region. 2,9 However, such model requires an unlikely multistep tunneling process or defect continuum with a wide energy band throughout a depletion region in semiconductor. Sawada et al 10 proposed a surface patch model to explain forward current characteristics.…”

mentioning

confidence: 99%

Leakage mechanism in GaN and AlGaN Schottky interfaces

Hashizume¹,

Kotani²,

Hasegawa³

2004

Applied Physics Letters

182

112

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Based on detailed temperature-dependent current-voltage (I -V -T) measurements the mechanism of leakage currents through GaN and AlGaN Schottky interfaces is discussed. The experiments were compared to calculations based on thin surface barrier model in which the effects of surface defects were taken into account. Our simulation method reproduced the experimental I -V -T characteristics of the GaN and AlGaN Schottky diodes, and gave excellent fitting results to the reported Schottky I -V curves in GaN for both forward and reverse biases at different temperatures. The present results indicate that the barrier thinning caused by unintentional surface-defect donors enhances the tunneling transport processes, leading to large leakage currents through GaN and AlGaN Schottky interfaces. © 2004 American Institute of Physics. ͓DOI: 10.1063/1.1762980͔ Although significant progress has been achieved in GaNbased high-power/high-frequency electronic devices and ultraviolet photodetectors, surface-related problems still need an immediate solution. In particular, leakage currents through Schottky contacts not only impede device reliability but also degrade power efficiency and noise performance in such devices. In spite of the fact that Schottky diodes formed on GaN and AlGaN are suffering from excess reverse leakage currents that are many orders of magnitude larger than the prediction of the thermionic emission ͑TE͒ model, 1-6 only a few studies have focused on the reverse-current characteristics quantitatively.Yu et al. 7 and Miller et al. 8 discussed the leakage mechanism in GaN and AlGaN Schottky interfaces on the basis of the field-emission ͑FE͒ tunneling transport assuming a triangular Schottky potential. However, unreasonably higher donor densities than the actual doping concentration were required in their calculation for reproduction of the experimental data. Thus, they expected some other processes such as defect-assisted tunneling to enhance leakage currents. Other groups also suggested the trap-assisted tunneling model to explain the leakage mechanism in the reverse bias region. 2,9 However, such model requires an unlikely multistep tunneling process or defect continuum with a wide energy band throughout a depletion region in semiconductor. Sawada et al. 10 proposed a surface patch model to explain forward current characteristics. Miller et al. 11 have recently suggested a leakage mechanism associated with a variablerange-hopping conduction through threading dislocations. However, little is known for the physical mechanism of excess leakage currents in GaN and AlGaN Schottky diodes.This letter discusses the mechanism of leakage currents through GaN Schottky interfaces, investigating transport properties of Schottky diodes using temperature-dependent current-voltage (I -V -T) measurements for both forward and reverse biases. A simulation method for the calculation of currents based on the thin surface barrier ͑TSB͒ model 5 is discussed. The measured currents were compared to the calculated ones for different tempe...

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“…So far, some possible mechanisms of I G have been proposed: based on the fact of high density of traps locating in the AlGaN barrier or on the AlGaN surface, I G could be formed by Poole-Frenkel (PF) emission 1 and phonon-assisted tunnelling; 2 due to the high electric field in the Schottky barrier, I G could be formed by Fowler-Nordheim (FN) tunneling 3 and thermionic field emission. 4,5 The electric field and also the leakage current near the gate edges have higher values than that in the other regions of the gate, 6 especially for the device under relative low V GS . Generally, the leakage current near the gate edges is considered to be negligible and so it is omitted in I G modelling for AlGaN/GaN HEMTs with long gate.…”

mentioning

confidence: 99%

Simulation of Gate Leakage Current of AlGaN/GaN HEMTs: Effects of the Gate Edges and Self-Heating

Wang

Zeng

Wang

2017

ECS J. Solid State Sci. Technol.

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The gate leakage current (I G ) of AlGaN/GaN high electron mobility transistors (HEMTs) at various ambient temperatures is simulated by considering its mechanism as domination of trap-assisted tunneling (TAT) and Poole-Frenkel (PF) emission for low electric field in the AlGaN barrier, and domination of Fowler-Nordheim (FN) tunneling for high electric field in the AlGaN barrier. Two bias cases are studied: V GS (gate voltage) variation while V DS (drain voltage) = 0 V without self-heating and V DS variation while V GS = 0 V with self-heating. For the first case, FN tunneling current mainly concentrates near the gate edges and so it is not changed with the gate length. While PF emission and TAT current do not show big variation along the gate, they are affected by the gate length and show higher values for longer gate. For the second case, with V DS increasing the elevated device temperature caused by the self-heating obviously increases PF emission and also increases I G because PF emission is the dominant mechanism of I G . With V DS further increasing, although the higher device temperature presents, I G is not affected by the self-heating because the temperature-independent FN tunneling becomes the dominant mechanism of I G . AlGaN/GaN high electron mobility transistors (HEMTs) present a big potential used in the field of high power, high temperature, and high frequency due to the wide bandgap of the materials as well as high electron mobility and saturation velocity in the transistors, which have attracted lot of researches in the past. Modelling/simulation and illustration of relevant mechanism of the gate leakage current (I G ) are important research aspects for AlGaN/GaN HEMTs, because usually I G can affect the device power efficiency and reliability. So far, some possible mechanisms of I G have been proposed: based on the fact of high density of traps locating in the AlGaN barrier or on the AlGaN surface, I G could be formed by Poole-Frenkel (PF) emission 1 and phonon-assisted tunnelling; 2 due to the high electric field in the Schottky barrier, I G could be formed by Fowler-Nordheim (FN) tunneling 3 and thermionic field emission. 4,5The electric field and also the leakage current near the gate edges have higher values than that in the other regions of the gate, 6 especially for the device under relative low V GS . Generally, the leakage current near the gate edges is considered to be negligible and so it is omitted in I G modelling for AlGaN/GaN HEMTs with long gate. While for the device with short gate, the leakage current near the gate edges is obvious and therefore it would be considered in the modelling. As far as we know, in the past, I G modelling has not addressed the self-heating effect since the studies were restricted to the device with V DS keeping zero (no self-heating). For the device with high power consumption, the self-heating could significantly increase the device temperature, 7,8 and any temperature-dependent I G should be influenced by the selfheating. In this paper, we will address ...

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Mechanism of the reverse gate leakage in AlGaN/GaN high electron mobility transistors

Cited by 121 publications

References 8 publications

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Leakage mechanism in GaN and AlGaN Schottky interfaces

Simulation of Gate Leakage Current of AlGaN/GaN HEMTs: Effects of the Gate Edges and Self-Heating

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