Molecular beam deposited zirconium dioxide as a high-κ dielectric for future GaN based power devices

Freese, Annett; Grube, Matthias; Wachowiak, Andre; Geidel, Marion; Adolphi, B.; Schmult, S.; Mikolajick, Thomas

doi:10.1116/1.4793764

Cited by 3 publications

(3 citation statements)

References 16 publications

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“…2 Compared to other high-j gate dielectric materials such as ZrO 2 (Ref. 2) and HfO 2 , Al 2 O 3 offers a larger bandgap with high conduction and valence band offsets to the GaN (Ref. 1) and, in addition, its dielectric constant of $9 allows for good gate coupling.…”

Section: Introductionmentioning

confidence: 99%

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Impact of postdeposition annealing upon film properties of atomic layer deposition-grown Al2O3 on GaN

Winzer¹,

Szabó²,

Wachowiak³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Atomic layer deposition-grown Al2O3 thin films are grown on n-type GaN and annealed at 300 or 500 °C in various atmospheres. Metal–insulator–semiconductor capacitors (MISCAPs) are used as simplified test structures for AlGaN/GaN heterostructure field effect transistors with an Al2O3 gate dielectric. Electrical characterization of the unannealed MISCAPs reveals a low leakage current density of ∼1.4 × 10−9 A/cm2 at −2 MV/cm. Annealing at 500 °C in N2 or a forming gas results in a degradation of this leakage level by more than one order of magnitude, whereas the leakage current of the Al2O3 films annealed at 500 °C in O2 is increased to ∼5.2 × 10−9 A/cm2 at −2 MV/cm. The photoassisted capacitance–voltage technique, the conductance method, and border trap analysis are used to study the influence of the annealing ambient atmosphere upon the Al2O3/GaN interface. For all atmospheres, thermal treatments at 500 °C marginally affects the border oxide trap density, but the forming gas anneal at 500 °C passivates the interface traps most efficiently. While the O2 thermal treatment reduces the interface trap density in the Al2O3/GaN system, the N2 anneal creates interface trap states, indicating the formation of an oxygen deficient defect level at the Al2O3/GaN interface during N2 annealing.

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Section: Introductionmentioning

confidence: 99%

“…1 In the past, suitable high-j dielectric materials have been developed and their fabrication has been transferred from Si-based technology to that of GaN. 2 Compared to other high-j gate dielectric materials such as ZrO 2 (Ref. 2) and HfO 2 , Al 2 O 3 offers a larger bandgap with high conduction and valence band offsets to the GaN (Ref.…”

Section: Introductionmentioning

confidence: 99%

Impact of postdeposition annealing upon film properties of atomic layer deposition-grown Al2O3 on GaN

Winzer¹,

Szabó²,

Wachowiak³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…However, the V TH was much lower than the expected value calculated using the Mg doping density and the gate capacitance, 5 GaN or homo-epitaxial GaN with low dislocation densities. [15][16][17] In this letter, accordingly, we report on fabrication and characterization of Al 2 O 3 /n-GaN structures using homoepitaxial GaN layers grown on a GaN substrate with a relatively low dislocation density, particularly focusing on interface state densities and the stability of capacitancevoltage (C-V) behavior. Figure 1 shows an Al 2 O 3 /n-GaN MOS structure prepared by ALD.…”

Section: à2mentioning

confidence: 99%

Highly-stable and low-state-density Al2O3/GaN interfaces using epitaxial n-GaN layers grown on free-standing GaN substrates

Kaneki

Ohira

Toiya

et al. 2016

Applied Physics Letters

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Interface characterization was carried out on Al2O3/GaN structures using epitaxial n-GaN layers grown on free-standing GaN substrates with relatively low dislocation density (<3 x 10(6) cm(-2)). The Al2O3 layer was prepared by atomic layer deposition. The as-deposited metal-oxide-semiconductor (MOS) sample showed a significant frequency dispersion and a bump-like feature in capacitance-voltage (C-V) curves at reverse bias, showing high-density interface states in the range of 10(12) cm(-1) eV(-1). On the other hand, excellent C-V characteristics with negligible frequency dispersion were observed from the MOS sample after annealing under a reverse bias at 300 degrees C in air for 3 h. The reverse-bias-annealed sample showed state densities less than 1 x 10(11) cm(-1) eV(-1) and small shifts of flat-band voltage. In addition, the C-V curve measured at 200 degrees C remained essentially similar compared with the room-temperature C-V curves. These results indicate that the present process realizes a stable Al2O3/GaN interface with low interface state densities

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Detailed analysis of oxide related charges and metal-oxide barriers in terrace etched Al2O3 and HfO2 on AlGaN/GaN heterostructure capacitors

Winzer

Szabó

Ocker

et al. 2015

Journal of Applied Physics

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Articles you may be interested inHigh quality HfO2/p-GaSb (001) metal-oxide-semiconductor capacitors with 0.8 nm equivalent oxide thickness Appl. Phys. Lett. 105, 222103 (2014); 10.1063/1.4903068 Quantitative characterization of interface traps in Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electronmobility transistors by dynamic capacitance dispersion technique Appl. Phys. Lett. 103, 033510 (2013); 10.1063/1.4813912 Study of gate oxide traps in HfO2/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors by use of ac transconductance method A comprehensive analytical model for threshold voltage calculation in GaN based metal-oxide-semiconductor high-electron-mobility transistors Appl. Phys. Lett. 100, 113509 (2012); 10.1063/1.3694768 Trap states in AlGaN/GaN metal-oxide-semiconductor structures with Al 2 O 3 prepared by atomic layer depositionIn this work, we present the terrace etching technique to obtain excessive thickness series of atomic layer deposition (ALD) grown Al 2 O 3 and HfO 2 on GaN-cap/AlGaN/GaN heterostructures allowing for the detailed study of oxide charge distribution and its impact of the metal-insulatorsemiconductor high electron mobility transistor (MISHEMT) threshold voltage. By modeling the experimental plot of threshold voltage versus oxide thickness on the basis of experimentally determined two-dimensional electron gas charge density in AlGaN/GaN MISHEMTs, we separated the interface and bulk charge components and determined the oxide-metal barrier height for the investigated gate dielectrics. In both Al 2 O 3 and HfO 2 gate dielectrics, the oxide charges are mainly located at the oxide/GaN interface. Determining the interface trap charges from comparison of the pulsed capacitance-voltage (CV) technique with very fast voltage sweep to the modulation type CV method with slow DC voltage ramp, we extracted positive fixed charges of N Ox ¼ 2:7 Â 10 12 cm À2 for Al 2 O 3 and N Ox ¼ 7:8 Â 10 12 cm À2 for HfO 2 . We found a strong V th shift of opposite direction for both high-k materials, corresponding to negatively charged up trap states at the HfO 2 /GaN interface and positively charged up trap states at the Al 2 O 3 /GaN interface. The evaluation of the metal-oxide barrier height in dependence of the metal work function followed the trend of the Schottky model, whereas HfO 2 showed less Fermi level pinning compared to Al 2 O 3 indicating the presence of an increased number of interface states in Al 2 O 3 on GaN. V C 2015 AIP Publishing LLC. [http://dx.

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Molecular beam deposited zirconium dioxide as a high-κ dielectric for future GaN based power devices

Cited by 3 publications

References 16 publications

Impact of postdeposition annealing upon film properties of atomic layer deposition-grown Al2O3 on GaN

Impact of postdeposition annealing upon film properties of atomic layer deposition-grown Al2O3 on GaN

Highly-stable and low-state-density Al2O3/GaN interfaces using epitaxial n-GaN layers grown on free-standing GaN substrates

Detailed analysis of oxide related charges and metal-oxide barriers in terrace etched Al2O3 and HfO2 on AlGaN/GaN heterostructure capacitors

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