# Enhancement of Breakdown Voltage in AlGaN/GaN HEMTs: Field Plate Plus High-k Passivation Layer and High Acceptor Density in Buffer Layer

Toshiki Kabemura, Shingo Ueda, Yuki Kawada, Kazushige Horio

Research output: Contribution to journalArticle

9 Citations (Scopus)

### Abstract

We make a 2-D analysis of breakdown characteristics of field-plate AlGaN/GaN HEMTs with a high- ${k}$ passivation layer, and the results are compared with those having a normal SiN passivation layer. As a result, it is found that the breakdown voltage is enhanced particularly in the cases with relatively short field plates because the reduction in the electric field at the drain edge of gate effectively improves the breakdown voltage in the case with the high- ${k}$ passivation layer. In the case with the moderate-length field plate, the enhancement of breakdown voltage due to the high- ${k}$ passivation layer occurs because the electric field profiles between the field-plate edge and the drain become more uniform. It is also studied how the breakdown voltage depends on a deep-acceptor density in the Fe-doped semi-insulating buffer layer when a high- ${k}$ passivation layer is used. It is shown that the breakdown voltage increases with increasing the relative permittivity of the passivation layer $\varepsilon -{\text{r}}$ and with increasing the deep-acceptor density NDA. When $\varepsilon -{\text{r}} = 60$ and $N-{\mathrm {DA}} = 2$ - $3 \times 10^{17}$ cm-3 at the gate length of $0.3~\mu \text{m}$ , the breakdown voltage becomes about 500 V at a gate-to-drain distance of $1.5~\mu \text{m}$ , which corresponds to an average electric field of about 3.3 MV/cm between the gate and the drain.

Original language English 8423447 3848-3854 7 IEEE Transactions on Electron Devices 65 9 https://doi.org/10.1109/TED.2018.2857774 Published - 2018 Sep 1

### Fingerprint

High electron mobility transistors
Buffer layers
Electric breakdown
Passivation
Electric fields
aluminum gallium nitride
Permittivity

### Keywords

• 2-D analysis
• breakdown characteristics
• buffer layer
• GaN HEMT
• high-k passivation layer

### ASJC Scopus subject areas

• Electronic, Optical and Magnetic Materials
• Electrical and Electronic Engineering

### Cite this

Enhancement of Breakdown Voltage in AlGaN/GaN HEMTs : Field Plate Plus High-k Passivation Layer and High Acceptor Density in Buffer Layer. / Kabemura, Toshiki; Ueda, Shingo; Kawada, Yuki; Horio, Kazushige.

In: IEEE Transactions on Electron Devices, Vol. 65, No. 9, 8423447, 01.09.2018, p. 3848-3854.

Research output: Contribution to journalArticle

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N2 - We make a 2-D analysis of breakdown characteristics of field-plate AlGaN/GaN HEMTs with a high- ${k}$ passivation layer, and the results are compared with those having a normal SiN passivation layer. As a result, it is found that the breakdown voltage is enhanced particularly in the cases with relatively short field plates because the reduction in the electric field at the drain edge of gate effectively improves the breakdown voltage in the case with the high- ${k}$ passivation layer. In the case with the moderate-length field plate, the enhancement of breakdown voltage due to the high- ${k}$ passivation layer occurs because the electric field profiles between the field-plate edge and the drain become more uniform. It is also studied how the breakdown voltage depends on a deep-acceptor density in the Fe-doped semi-insulating buffer layer when a high- ${k}$ passivation layer is used. It is shown that the breakdown voltage increases with increasing the relative permittivity of the passivation layer $\varepsilon -{\text{r}}$ and with increasing the deep-acceptor density NDA. When $\varepsilon -{\text{r}} = 60$ and $N-{\mathrm {DA}} = 2$ - $3 \times 10^{17}$ cm-3 at the gate length of $0.3~\mu \text{m}$ , the breakdown voltage becomes about 500 V at a gate-to-drain distance of $1.5~\mu \text{m}$ , which corresponds to an average electric field of about 3.3 MV/cm between the gate and the drain.

AB - We make a 2-D analysis of breakdown characteristics of field-plate AlGaN/GaN HEMTs with a high- ${k}$ passivation layer, and the results are compared with those having a normal SiN passivation layer. As a result, it is found that the breakdown voltage is enhanced particularly in the cases with relatively short field plates because the reduction in the electric field at the drain edge of gate effectively improves the breakdown voltage in the case with the high- ${k}$ passivation layer. In the case with the moderate-length field plate, the enhancement of breakdown voltage due to the high- ${k}$ passivation layer occurs because the electric field profiles between the field-plate edge and the drain become more uniform. It is also studied how the breakdown voltage depends on a deep-acceptor density in the Fe-doped semi-insulating buffer layer when a high- ${k}$ passivation layer is used. It is shown that the breakdown voltage increases with increasing the relative permittivity of the passivation layer $\varepsilon -{\text{r}}$ and with increasing the deep-acceptor density NDA. When $\varepsilon -{\text{r}} = 60$ and $N-{\mathrm {DA}} = 2$ - $3 \times 10^{17}$ cm-3 at the gate length of $0.3~\mu \text{m}$ , the breakdown voltage becomes about 500 V at a gate-to-drain distance of $1.5~\mu \text{m}$ , which corresponds to an average electric field of about 3.3 MV/cm between the gate and the drain.

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