The role of the tunneling component in the current–voltage characteristics of metal-GaN Schottky diodes

Yu, L. S.; Liu, Q. Z.; Qian, Xing; Qiao, D.; Lau, S. S.; Redwing, Joan M.

doi:10.1063/1.368270

Cited by 178 publications

(105 citation statements)

References 14 publications

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“…However, some crucial problems such as large leakage current in Schottky contacts [1][2][3][4] and drain current collapse [5,6] that are related to the AlGaN surface are not completely solved. Degradation of output power under large bias and high frequency conditions due to these is particularly serious for enhancement high-power/high-frequency performances of AlGaN/GaN HFETs [7].…”

Section: Introductionmentioning

confidence: 99%

Tunneling Injection of Electrons at Nanometer-Scale Schottky Gate Edge of AlGaN/GaN Heterostructure Transistors and Its Computer Simulation

Kotani

Kasai

Hasegawa

et al. 2005

e-J. Surf. Sci. Nanotechnol.

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Gate leakage currents in AlGaN/GaN HFETs were investigated by comparing experiments with computer simulations based on the thin surface barrier (TSB) model involving unintentional surface donors. Leakage currents in large area Schottky diodes were explained by the TSB model involving nitrogen vacancy related deep donors and oxygen shallow donors. On the other hand, in AlGaN/GaN HFETs with nanometer scale Schottky gates, gate leakage currents include an additional leakage component due to lateral electron injection through tunneling at the gate edge where the barrier thinning is mainly controlled by oxygen donors. By combining vertical and lateral tunneling components, experiments could be reproduced on computer. Lateral components may be responsible for current collapse.

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Section: Introductionmentioning

confidence: 99%

Tunneling Injection of Electrons at Nanometer-Scale Schottky Gate Edge of AlGaN/GaN Heterostructure Transistors and Its Computer Simulation

Kotani

Kasai

Hasegawa

et al. 2005

e-J. Surf. Sci. Nanotechnol.

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“…12 We also attempted to fit the experimental I -V data of GaN Schottky diodes from other groups. Figure 3 shows forward I -V -T curves of Ni/n-GaN and Ag/n-GaN diodes reported by Yu et al 7 and Sawada et al, 10 respectively. Also shown are the calculation results by the present simulation.…”

mentioning

confidence: 99%

“…This indicated that both samples included large amounts of surface defect donors at GaN surfaces. In fact, Yu et al 7 expected the enhancement of tunneling components due to the large amount of defects in GaN.…”

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confidence: 99%

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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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“…Yu et al 3) and Miller et al 4) discussed the leakage mechanism in GaN and AlGaN Schottky interfaces on the basis of field-emission tunneling transport assuming a triangular Schottky potential. However, unreasonably higher donor densities than the actual doping concentration were necessary in their calculation to reproduce experimental data.…”

mentioning

confidence: 99%

Surface Control Process of AlGaN for Suppression of Gate Leakage Currents in AlGaN/GaN Heterostructure Field Effect Transistors

Hashizume

Kotani

Basile

et al. 2006

jjap

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We proposed a surface control process for suppressing the tunneling leakage of Schottky gates on AlGaN/GaN heterostructures. For the recovery of nitrogen-vacancy-related defects and reduction in the amount of oxygen impurities at the AlGaN surface, the process consisted of nitrogen radical treatment, the deposition of an ultrathin Al layer, UHV annealing and finally the removal of the Al layer. Ni/Au Schottky gates fabricated on processed AlGaN surfaces showed pronounced reduction in leakage current and a clear temperature dependence of I-V characteristics, indicating the effective suppression of tunneling leakage in current transport through AlGaN Schottky interfaces.

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The role of the tunneling component in the current–voltage characteristics of metal-GaN Schottky diodes

Cited by 178 publications

References 14 publications

Tunneling Injection of Electrons at Nanometer-Scale Schottky Gate Edge of AlGaN/GaN Heterostructure Transistors and Its Computer Simulation

Tunneling Injection of Electrons at Nanometer-Scale Schottky Gate Edge of AlGaN/GaN Heterostructure Transistors and Its Computer Simulation

Leakage mechanism in GaN and AlGaN Schottky interfaces

Surface Control Process of AlGaN for Suppression of Gate Leakage Currents in AlGaN/GaN Heterostructure Field Effect Transistors

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