Two-dimensional analysis of substrate-trap effects on turn-on characteristics in GaAs MESFETs

Horio, K.; Wakabayashi, A.; Yamada, T.

doi:10.1109/16.824738

Cited by 21 publications

(7 citation statements)

References 17 publications

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“…Because of this increase in negative space charges in the buffer layer, even if V G is switched on, I D remains at a low value until the deep donors begin to emit electrons, showing gate-lag behavior. It should be mentioned that this type of gate lag is not observed in the similar simulation for GaAs MESFETs with deep donors ''EL2'' and shallow acceptors in the substrate, 20) where visible potential drops are not observed in the on state between source and gate. This is because the current density is relatively low and the parasitic resistance is low due to the higher electron mobility.…”

Section: Drain Lagmentioning

confidence: 75%

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Physical Mechanism of Buffer-Related Current Transients and Current Slump in AlGaN/GaN High Electron Mobility Transistors

Horio

Nakajima

2008

jjap

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Two-dimensional transient analyses of AlGaN/GaN high electron mobility transistors (HEMTs) are performed in which a deep donor and a deep acceptor are considered in a buffer layer. Quasi-pulsed current-voltage (I-V) curves are derived from the transient characteristics. When the drain voltage is raised abruptly, electrons are injected into the buffer layer and captured by deep donors, and when it is lowered abruptly, the drain currents remain at low values for some periods and begin to increase slowly as the deep donors begin to emit electrons, showing drain-lag behavior. The gate lag could also occur due to deep levels in the buffer layer, and it is correlated with relatively high source access resistance in AlGaN/GaN HEMTs. It is shown that the current slump is more pronounced when the deep-acceptor density in the buffer layer is higher and when an off-state drain voltage is higher, because the trapping effects become more significant. The drain lag could be a major cause of current slump in the case of higher off-state drain voltage. It is suggested that to minimize current slump in AlGaN/GaN HEMTs, an acceptor density in the buffer layer should be made low, although there may be a trade-off relationship between reducing current slump and obtaining sharp current cutoff.

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Section: Drain Lagmentioning

confidence: 75%

“…Basic equations to be solved are Poisson's equation including ionized deep-level terms, continuity equations for electrons and holes which include carrier loss rates via the deep levels, and rate equations for the deep levels. 14,20) They are expressed as follows. 1) Poisson's equation…”

Section: Physical Modelmentioning

confidence: 99%

Physical Mechanism of Buffer-Related Current Transients and Current Slump in AlGaN/GaN High Electron Mobility Transistors

Horio

Nakajima

2008

jjap

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“…Basic equations are Poisson's equation having the ionized deep-acceptor density term and electron and hole continuity equations which include a carrier loss rate via the deep acceptor and an impact ionization rate. 7,[15][16][17] The carrier generation rate by impact ionization G is expressed as…”

mentioning

confidence: 99%

Effects of acceptors in a Fe-doped buffer layer on breakdown characteristics of AlGaN/GaN high electron mobility transistors with a high-kpassivation layer

Kawada

Hanawa

Horio³

2017

Jpn. J. Appl. Phys.

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We analyze off-state breakdown characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) with a Fe-doped buffer layer where a deep acceptor located above the midgap is included. It is shown that by introducing a high-k passivation layer, the breakdown voltage Vbr improves as in a case with an undoped semi-insulating buffer layer. In the Fe-doped case, Vbr becomes a little higher in the case where the passivation layer’s relative permittivity εr is rather higher when the energy levels determining the Fermi level are set equal in the two buffers. It is also shown that when the energy level of deep acceptor is deeper, Vbr becomes higher in the region where εr is high. This occurs because the leakage current via the buffer layer becomes smaller.

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“…Basic equations are Poisson's equation, continuity equations for electrons and holes, which include carrier loss rates via the deep levels and a carrier generation rate by impact ionization, and rate equations for the deep levels. 10,[20][21][22][23][24] The carrier generation rate is expressed as…”

Section: Physical Modelmentioning

confidence: 99%

Analysis of high-kpassivation-layer effects on buffer-related breakdown and current collapse in AlGaN/GaN HEMTs

Satoh

Hanawa

Nakajima

et al. 2015

Jpn. J. Appl. Phys.

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We analyze breakdown characteristics and current collapse in AlGaN/GaN HEMTs, with the passivation layer's relative permittivity ε r as a parameter. It is shown that the off-state breakdown voltage is considerably enhanced by introducing a high-k passivation layer because the electric field at the drain edge of the gate is weakened and the buffer leakage current is reduced. The breakdown voltage in the high-ε r region increases when the gate voltage is changed from %8 to %10 V, because the buffer leakage current is reduced. It is also shown that drain lag and current collapse in AlGaN/GaN HEMTs could be reduced by introducing a high-k thick passivation layer, because the electric field at the drain edge of the gate is reduced, leading to less electron injection into the buffer layer and weaker buffer trapping effects.

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Two-dimensional analysis of substrate-trap effects on turn-on characteristics in GaAs MESFETs

Cited by 21 publications

References 17 publications

Physical Mechanism of Buffer-Related Current Transients and Current Slump in AlGaN/GaN High Electron Mobility Transistors

Physical Mechanism of Buffer-Related Current Transients and Current Slump in AlGaN/GaN High Electron Mobility Transistors

Effects of acceptors in a Fe-doped buffer layer on breakdown characteristics of AlGaN/GaN high electron mobility transistors with a high-kpassivation layer

Analysis of high-kpassivation-layer effects on buffer-related breakdown and current collapse in AlGaN/GaN HEMTs

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