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. 2022 May 22;13(5):807.
doi: 10.3390/mi13050807.

Hole Injection Effect and Dynamic Characteristic Analysis of Normally Off p-GaN HEMT with AlGaN Cap Layer on Low-Resistivity SiC Substrate

Hsiang-Chun Wang  1   2   3 , Chia-Hao Liu  3 , Chong-Rong Huang  3 , Hsien-Chin Chiu  3   4 , Hsuan-Ling Kao  3   4 , Xinke Liu  2
Affiliations

Hole Injection Effect and Dynamic Characteristic Analysis of Normally Off p-GaN HEMT with AlGaN Cap Layer on Low-Resistivity SiC Substrate

Hsiang-Chun Wang et al. Micromachines (Basel). .

Abstract

A p-GaN HEMT with an AlGaN cap layer was grown on a low resistance SiC substrate. The AlGaN cap layer had a wide band gap which can effectively suppress hole injection and improve gate reliability. In addition, we selected a 0° angle and low resistance SiC substrate which not only substantially reduced the number of lattice dislocation defects caused by the heterogeneous junction but also greatly reduced the overall cost. The device exhibited a favorable gate voltage swing of 18.5 V (@IGS = 1 mA/mm) and an off-state breakdown voltage of 763 V. The device dynamic characteristics and hole injection behavior were analyzed using a pulse measurement system, and Ron was found to increase and VTH to shift under the gate lag effect.

Keywords: VTH shifting; dynamic Ron; hole injection; normally-off; p-GaN E-mode HEMT.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) Cross-sectional schematic of the p-GaN gate HEMT, and (b) the etching stop technique.
Figure 2
Figure 2
Device’s dc characteristics with LGS, LG, LGD, and WG = 2, 5, 10, and 100 μm, respectively: (a) transfer and (b) output characteristics.
Figure 3
Figure 3
(a) IGS−VGS characteristic and (b) off−state breakdown voltage measurement of the device.
Figure 4
Figure 4
(a) Condition of pulse measurement and (b) gate lag characteristic.
Figure 5
Figure 5
(a) Dynamic transfer characteristics measured for various stress durations, and (b) VTH shifting for different VGSQ.
Figure 6
Figure 6
Schematic of the band diagram gate region of a p-GaN HEMT operating at (a) 1 V < VGS < 5 V, (b) 5 V < VGS < 15 V, and (c) VGS > 15 V.
Figure 7
Figure 7
(a) IDS–VGS characteristics of the device at 25 °C to 175 °C, and (b) variation in VTH and Ron.
Figure 8
Figure 8
VTH and Ron distributions for 30 devices.
Figure 9
Figure 9
Comparison with other teams of the VGB−D and IGS−Leakage.
See this image and copyright information in PMC

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