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Donor-like surface traps on two-dimensional electron gas and current collapse of AlGaN/GaN HEMTs.

Yu CH, Luo QZ, Luo XD, Liu PS - ScientificWorldJournal (2013)

Bottom Line: The depletion of 2DEG by the donor-like surface states is shown.By adopting an optimized backside doping scheme, the electron density of 2DEG has been improved greatly and the current collapse has been greatly eliminated.These results give reference to the improvement in device performance of AlGaN/GaN HEMTs.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of ASIC Design, Nantong University, Nantong 226019, China.

ABSTRACT
The effect of donor-like surface traps on two-dimensional electron gas (2DEG) and drain current collapse of AlGaN/GaN high electron mobility transistors (HEMTs) has been investigated in detail. The depletion of 2DEG by the donor-like surface states is shown. The drain current collapse is found to be more sensitive to the addition of positive surface charges. Surface trap states with higher energy levels result in weaker current collapse and faster collapse process. By adopting an optimized backside doping scheme, the electron density of 2DEG has been improved greatly and the current collapse has been greatly eliminated. These results give reference to the improvement in device performance of AlGaN/GaN HEMTs.

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Cross-sectional structure of AlGaN/GaN HEMT. Positive sheet charge +σpol is caused by spontaneous polarization and piezoelectric effect. Equivalent negative sheet charge −σpol is fixed on the AlGaN surface. Surface trap states are represented with ±σT.
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fig1: Cross-sectional structure of AlGaN/GaN HEMT. Positive sheet charge +σpol is caused by spontaneous polarization and piezoelectric effect. Equivalent negative sheet charge −σpol is fixed on the AlGaN surface. Surface trap states are represented with ±σT.

Mentions: Two-dimensional drift-diffusion simulations of the AlGaN/GaN HEMTs are performed. Device structure of the AlGaN/GaN HEMT is shown in Figure 1. The gate length is 0.7 μm and the opening spaces between the contacts are LGD = 0.7 μm and LSG = 2 μm. The thickness of AlGaN layer with composition of 35% aluminum is 29 nm. The mobilities of electrons and holes in GaN layer are 100 cm2 V−1 s−1and 30 cm2 V−1 s−1, respectively. The mobilities of electrons and holes in AlGaN layer are 100 cm2 V−1 s−1 and 5 cm2 V−1 s−1, respectively [9, 17–21].


Donor-like surface traps on two-dimensional electron gas and current collapse of AlGaN/GaN HEMTs.

Yu CH, Luo QZ, Luo XD, Liu PS - ScientificWorldJournal (2013)

Cross-sectional structure of AlGaN/GaN HEMT. Positive sheet charge +σpol is caused by spontaneous polarization and piezoelectric effect. Equivalent negative sheet charge −σpol is fixed on the AlGaN surface. Surface trap states are represented with ±σT.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3852575&req=5

fig1: Cross-sectional structure of AlGaN/GaN HEMT. Positive sheet charge +σpol is caused by spontaneous polarization and piezoelectric effect. Equivalent negative sheet charge −σpol is fixed on the AlGaN surface. Surface trap states are represented with ±σT.
Mentions: Two-dimensional drift-diffusion simulations of the AlGaN/GaN HEMTs are performed. Device structure of the AlGaN/GaN HEMT is shown in Figure 1. The gate length is 0.7 μm and the opening spaces between the contacts are LGD = 0.7 μm and LSG = 2 μm. The thickness of AlGaN layer with composition of 35% aluminum is 29 nm. The mobilities of electrons and holes in GaN layer are 100 cm2 V−1 s−1and 30 cm2 V−1 s−1, respectively. The mobilities of electrons and holes in AlGaN layer are 100 cm2 V−1 s−1 and 5 cm2 V−1 s−1, respectively [9, 17–21].

Bottom Line: The depletion of 2DEG by the donor-like surface states is shown.By adopting an optimized backside doping scheme, the electron density of 2DEG has been improved greatly and the current collapse has been greatly eliminated.These results give reference to the improvement in device performance of AlGaN/GaN HEMTs.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of ASIC Design, Nantong University, Nantong 226019, China.

ABSTRACT
The effect of donor-like surface traps on two-dimensional electron gas (2DEG) and drain current collapse of AlGaN/GaN high electron mobility transistors (HEMTs) has been investigated in detail. The depletion of 2DEG by the donor-like surface states is shown. The drain current collapse is found to be more sensitive to the addition of positive surface charges. Surface trap states with higher energy levels result in weaker current collapse and faster collapse process. By adopting an optimized backside doping scheme, the electron density of 2DEG has been improved greatly and the current collapse has been greatly eliminated. These results give reference to the improvement in device performance of AlGaN/GaN HEMTs.

Show MeSH
Related in: MedlinePlus