Insulated gate and surface passivation structures for GaN-based power transistors

Yatabe, Zenji; Asubar, Joel T.; Hashizume, Tamotsu

doi:10.1088/0022-3727/49/39/393001

Cited by 182 publications

(105 citation statements)

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“…2 and 4(b) suggest that by using an appropriate high x, in the case of SiO 2 /AlGaN/GaN and SiN/AlGaN/GaN structures, one can obtain a reduced Q f to the negligible value and, as a result, shifting V th to the region of the positive gate voltage, which ensures normally off operation. 2 In conclusion, we found that the positive fixed charge Q f at the insulator/Al x Ga 1-x N interfaces exhibits a significant decrease with increasing x, which results in the V th shift towards the positive gate voltage. We examined this result with respect to the various hypotheses developed in the literature to explain the origin of the positive Q f at insulator/III-N interfaces.…”

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confidence: 58%

“…In the case of both types of structures, we observed a significant V th shift in C-V curves towards the more positive gate voltage with increasing x. In particular, for SiO 2 /Al x Ga 1-x N/GaN structures, an increase of x from 0.15 to 0.4 caused the V th shift from À17 to À7.5 V and for SiN/Al x Ga 1-x N/GaN structures from À9.5 to À5 V. Due to such a large shift, we could observe typical of MISH structures two-step C-V curves 2,3,18 only in the case of x ¼ 0.15. In addition, for comparison, in the inset of Fig.…”

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confidence: 77%

“…[1][2][3][4][5][6][7][8][9][10] However, achieving normally-off or enhancement mode transistors with the positive threshold voltage (V th ), which exhibit good performance, still remains a major challenge. 2 The key feature of the precise tuning of V th in GaN-based MISHEMTs is the control of the positive fixed charge (Q f ) at the insulator/III-N interfaces. 11 The positive Q f was reported for Al 2 O 3 /(Al, Ga)N, [12][13][14][15] SiO 2 /AlGaN, 15 and SiN/AlGaN 16,17 interfaces.…”

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confidence: 99%

“…1 2 and SiN layers, respectively. All heterojunction samples were cleaned with a HF solution before the insulator deposition in order to mitigate native oxides at the airexposed AlGaN surfaces.…”

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confidence: 99%

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Origin of positive fixed charge at insulator/AlGaN interfaces and its control by AlGaN composition

Matys

Stoklas

Blaho

et al. 2017

Applied Physics Letters

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The key feature for the precise tuning of Vth in GaN-based metal-insulator-semiconductor (MIS) high electron mobility transistors is the control of the positive fixed charge (Qf) at the insulator/III-N interfaces, whose amount is often comparable to the negative surface polarization charge (Qpol−). In order to clarify the origin of Qf, we carried out a comprehensive capacitance-voltage (C-V) characterization of SiO2/AlxGa1–xN/GaN and SiN/AlxGa1–xN/GaN structures with Al composition (x) varying from 0.15 to 0.4. For both types of structures, we observed a significant Vth shift in C-V curves towards the positive gate voltage with increasing x. On the contrary, the Schottky gate structures exhibited Vth shift towards the more negative biases. From the numerical simulations of C-V curves using the Poisson's equation supported by the analytical calculations of Vth, we showed that the Vth shift in the examined MIS structures is due to a significant decrease in the positive Qf with rising x. Finally, we examined this result with respect to various hypotheses developed in the literature to explain the origin of the positive Qf at insulator/III-N interfaces.

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confidence: 58%

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confidence: 77%