Significant increase in conduction band discontinuity due to solid phase epitaxy of Al2O3 gate insulator films on GaN semiconductor

Toyoda, Satoshi; Shinohara, Takayuki; Kumigashira, Hiroshi; Oshima, Masaharu; Kato, Y.

doi:10.1063/1.4769818

Cited by 66 publications

(48 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Through a band alignment based on hybrid functional calculations, it is inferred that the corresponding defect levels lie at ∼1 eV above the conduction band minimum of In 0.53 Ga 0. 47 As, in agreement with measured defect densities. These results support the technological importance of avoiding cation diffusion into the oxide layer.…”

supporting

confidence: 78%

“…47 As/Al 2 O 3 interfaces. Through density-functional calculations, these defects are found to be thermodynamically stable in amorphous Al 2 O 3 and to be able to capture two electrons in a dangling bond upon breaking bonds with neighboring O atoms.…”

mentioning

confidence: 99%

“…47 As (here referred to as InGaAs) has suitable electronic properties for microelectronic devices and can easily be grown onto InP substrates.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Nature of electron trap states under inversion at In0.53Ga0.47As/Al2O3 interfaces

Colleoni

Pourtois

Pasquarello

2017

Applied Physics Letters

View full text Add to dashboard Cite

In and Ga impurities substitutional to Al in the oxide layer resulting from diffusion out of the substrate are identified as candidates for electron traps under inversion at In 0.53 Ga 0.47 As/Al 2 O 3 interfaces. Through density-functional calculations, these defects are found to be thermodynamically stable in amorphous Al 2 O 3 and to be able to capture two electrons in a dangling bond upon breaking bonds with neighboring O atoms. Through a band alignment based on hybrid functional calculations, it is inferred that the corresponding defect levels lie at ∼1 eV above the conduction band minimum of In 0.53 Ga 0.47 As, in agreement with measured defect densities. These results support the technological importance of avoiding cation diffusion into the oxide layer.The microelectronic industry is investigating high mobility semiconductors for replacing silicon as substrate material. Among the III-V compounds, the In x Ga 1−x As family has gathered large interest for application in n-type devices.1 In particular, the compound In 0.53 Ga 0.47 As (here referred to as InGaAs) has suitable electronic properties for microelectronic devices and can easily be grown onto InP substrates.1,2 Amorphous Al 2 O 3 is the preferred dielectric owing to its wide bandgap, high breakdown field, and high thermal stability. 2Several passivation procedures have been considered to reduce the high density of interfacial defect states occurring at III-V/oxide interfaces (D it ).3-7 The origin of these states has been for long debated and recently assigned to As-As dimer bonds. [8][9][10][11][12][13] In addition to these interfacial states, a high density of oxide traps (D ot ) has recently been detected in the oxide layer of metal-oxide-semiconductor (MOS) devices. Capacitancevoltage (CV) measurements show a bimodal distribution for the density of defect states in the oxide, 14 with one peak at 1.5 eV above and the other at 0.5 eV below the CBM of InGaAs. Similarly, through positive bias temperature instability (PBTI) experiments, a wide distribution of defect states centered at about 1 eV above the InGaAs conduction band maximum (CBM) has been inferred.15 These states are considered to be at the origin of the degradation of the electrical properties, thereby compromising the performance of the corresponding MOS devices.14,15 Indeed, upon reaching the inversion of carrier population, the Fermi energy is pushed deep into the conduction band of InGaAs in order to achieve high carrier concentrations, and is then susceptible to defects in the upper part of the oxide band gap. The atomic origin of these defects has remained elusive. A hint might come from electrical measurements on InGaAs/Al 2 O 3 and Ge/GeO x /Al 2 O 3 interfaces which yield similar field acceleration factors, 16 but an assessment concerning the nature of the involved defects remains out of reach on this basis. More indicatively, a) Electronic mail: davide.colleoni@epfl.ch time-of-flight secondary ion mass spectroscopy studies on GaAs/Al 2 O 3 and InGaAs/Al 2 O 3 interfaces revea...

show abstract

supporting

confidence: 78%

mentioning

confidence: 99%

See 1 more Smart Citation

Nature of electron trap states under inversion at In0.53Ga0.47As/Al2O3 interfaces

Colleoni

Pourtois

Pasquarello

2017

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…Al 2 O 3 was one of the earliest candidates considered to replace SiO 2 as the CMOS gate dielectric, but has since been supplanted by HfO 2 primarily due to its higher dielectric constant (Al 2 O 3 k = 8-10 vs. HfO 2 k ∼ 25). 2 However, due to large band gaps [2][3][4] and favorable valence and conduction band alignments, 4,[67][68][69] Al 2 O 3 and HfO 2 both continue to play an important role as highk dielectrics in three-dimensional (3D) memory and energy storage structures, 14,20 RF blocking/decoupling capacitors, 15,20 high-mobility and tunnel field effect III-V devices, [70][71][72] high-power, high-frequency, and high-temperature III-N devices, 21,22,73,74 and 2D transition metal dichalcogenide CMOS devices. [75][76][77] In addition, the high thermodynamic stability 29 and atomic/mass density 28 of Al 2 O 3 has enabled it to serve as an optical coating material, 30 surface passivation layer in Si solar cells, 16,78 hermetic encapsulation layer for OLED and packaging applications, 34,35 metal 36 and gas 27,31,32 diffusion barrier in microelectronic applications, and as a corrosion and stiction protection layer in NEM devices.…”

Section: Ecs Journal Of Solid State Science and Technology 6 (10) N1mentioning

confidence: 99%

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

Gaskins

Hopkins

Merrill

et al. 2017

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

Atomic layer deposited (ALD) high-dielectric-constant (high-k) materials have found extensive applications in a variety of electronic, optical, optoelectronic, and photovoltaic devices. While electrical, optical, and interfacial properties have been the primary consideration for such devices, thermal and mechanical properties are becoming an additional key consideration for many new and emerging applications of ALD high-k materials in electromechanical, energy storage, and organic light emitting diode devices. Unfortunately, a clear correspondence between thermal/mechanical and electrical/optical properties in ALD high-k materials has yet to be established, and a detailed comparison to conventional silicon-based dielectrics to facilitate optimal material selection is also lacking. In this regard, we have conducted a comprehensive investigation and review of the thermal, mechanical, electrical, optical, and structural properties for a series of prevalent and emerging ALD high-k materials including aluminum oxide (Al 2 O 3 ), aluminum nitride (AlN), hafnium oxide (HfO 2 ), and beryllium oxide (BeO). For comparison, more established silicon-based dielectrics were also examined, including thermally grown silicon dioxide (SiO 2 ) and plasma-enhanced chemically vapor deposited hydrogenated silicon nitride (SiN:H). We find that in addition to exhibiting high values of dielectric permittivity and electrical resistance that exceed those of SiO 2 and SiN:H, the ALD high-k materials exhibit equally exceptional thermal and mechanical properties with coefficients of thermal expansion ≤ 6 × 10 -6 / • C, thermal conductivites (κ) of 3-15 W/m K, and Young's modulus and hardness values exceeding 200 and 25 GPa, respectively. In many cases, the observed extreme thermal/mechanical properties correlate with the presence of crystallinity in the ALD high-k films. In contrast, some of the electrical and optical properties correlate more strongly with the percentage of ionic vs. covalent bonds present in the high-k film. Overall, the ALD high-k dielectrics investigated concurrently exhibit compelling thermal/mechanical and electrical/optical properties. The drive to reduce gate leakage currents in highly scaled complementary metal-oxide-semiconductor (CMOS) transistors has led to the exploration and development of a wide variety of high-dielectricconstant (high-k) materials to replace silicon dioxide (SiO 2 ) as the insulating gate dielectric material.1-8 Many of these same high-k materials have found additional applications in future non-CMOS logic and memory storage products such as solid-state electrolytes in resistive switching devices, 9,10 tunnel barriers in spin-transport devices, 11 and as a ferroelectric in magnetoelectric devices. While electrical, physical, and thermodynamic properties have clearly been a key consideration in all of the above applications, thermal properties have become an additional important consideration for higk-k dielectrics as aggressive dimensional scaling of devices has created the need to dissipate ...

show abstract

“…In addition, Al 2 O 3 is amorphous and remained unchanged, i.e., no phase transformation even after post-deposition annealing process in the temperature range of 300-500 C. This is consistent with the fact that the phase transformation of Al 2 O 3 films from amorphous to crystalline happens at temperature of 800 C or higher. 11,20 Figure 3(a) shows the room-temperature (RT) C-V characteristics of the as-deposited Al 2 O 3 /n-GaN/n þ -GaN diode (without annealing) in a wide measurement frequency range of 1 Hz to 1 MHz. The sample showed a significant frequency dispersion at reverse bias.…”

Section: à3mentioning

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

View full text Add to dashboard Cite

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

show abstract

Significant increase in conduction band discontinuity due to solid phase epitaxy of Al2O3 gate insulator films on GaN semiconductor

Cited by 66 publications

References 23 publications

Nature of electron trap states under inversion at In0.53Ga0.47As/Al2O3 interfaces

Nature of electron trap states under inversion at In0.53Ga0.47As/Al2O3 interfaces

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

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

Contact Info

Product

Resources

About