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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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Related in: MedlinePlus

(a) Electric field intensity versus X direction. (b) Electric field intensity versus Y direction.
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fig3: (a) Electric field intensity versus X direction. (b) Electric field intensity versus Y direction.

Mentions: The electric field intensities in both X and Y direction as the surface charges, σT, change from 0 to −5 × 1012 cm−2 are shown in Figure 3. The electric field intensity in X direction is cut at AlGaN/GaN interface, Y = 0 nm, and in Y direction is cut at X = 0.25 nm, as shown in Figure 1. The electric field intensity in both X and Y directions decreases as the negative surface charge density is increased. The decrease of electric field intensity is consistent with the decrease of electron density in Figure 2 and produces positive consequences. Firstly, since the electric field intensity near the interface is reduced, the electrons in the channel cannot acquire high enough temperature, and the number of hot electrons reduces. Moreover, the addition of negative charges at surface makes surface potential lower and interface potential higher [28, 29], which in turn causes the electron affinity to increase. The higher electron affinity causes again the reduction of the amount of hot electrons. Secondly, the quantum tunneling effect is weakened with the increase of potential barrier and the decrease of electron energy [30]. The weakening of both hot electron and quantum tunneling effects prevents electrons escaping from the channel. Therefore, the increase of the negative charges on the surface is helpful in eliminating the drain current collapse.


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)

(a) Electric field intensity versus X direction. (b) Electric field intensity versus Y direction.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: (a) Electric field intensity versus X direction. (b) Electric field intensity versus Y direction.
Mentions: The electric field intensities in both X and Y direction as the surface charges, σT, change from 0 to −5 × 1012 cm−2 are shown in Figure 3. The electric field intensity in X direction is cut at AlGaN/GaN interface, Y = 0 nm, and in Y direction is cut at X = 0.25 nm, as shown in Figure 1. The electric field intensity in both X and Y directions decreases as the negative surface charge density is increased. The decrease of electric field intensity is consistent with the decrease of electron density in Figure 2 and produces positive consequences. Firstly, since the electric field intensity near the interface is reduced, the electrons in the channel cannot acquire high enough temperature, and the number of hot electrons reduces. Moreover, the addition of negative charges at surface makes surface potential lower and interface potential higher [28, 29], which in turn causes the electron affinity to increase. The higher electron affinity causes again the reduction of the amount of hot electrons. Secondly, the quantum tunneling effect is weakened with the increase of potential barrier and the decrease of electron energy [30]. The weakening of both hot electron and quantum tunneling effects prevents electrons escaping from the channel. Therefore, the increase of the negative charges on the surface is helpful in eliminating the drain current collapse.

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