Electronic properties of air-exposed GaN(11-00) and (0001) surfaces after several device processing compatible cleaning steps

Auzelle, Thomas; Ullrich, Florian; Hietzschold, Sebastian; Brackmann, Stefan; Hillebrandt, Sabina; Kowalsky, Wolfgang; Mankel, Eric; Lovrinčić, Robert; Fernández-Garrido, Sergio

doi:10.1016/j.apsusc.2019.07.256

Cited by 8 publications

(15 citation statements)

References 61 publications

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“…6 The presence of Cl was reported on a GaN surface after HCl treatment, with the effect of higher Cl coverage leading to lower oxygen coverage. 14,20,21 The lowest R rms values are obtained for NH 4 OH-and H 2 SO 4 /H 2 O 2 -treated samples (A3, B3, A5, and B5), in agreement with the literature, where H 2 O 2 /H 2 SO 4 solutions are reported to be the most favorable conditions for Al 2 O 3 deposition, compared to HF and HCl, 6 and for the smoothing of the GaN surface. 15 For these low roughness samples, the R rms value is lower for as-epi samples (A3 and A5) than etched samples (B3 and B5).…”

Section: Resultsmentioning

confidence: 99%

Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH

Vauche

Chanuel

Martínez

et al. 2021

ACS Appl. Electron. Mater.

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Understanding the impact of GaN surface treatment conditions on dielectric/GaN interface chemical properties is critically important for device performance. This point is under intensive research for the dielectric/GaN structure because GaN does not have a good native oxide quality such as SiO2 used in silicon technologies. The effects of different wet treatments prior to atomic layer deposition (ALD) of thin Al2O3 on Ga-polar GaN were studied by X-ray photoelectron spectroscopy (XPS). The same wet treatments have been applied to the recessed region of AlGaN/GaN heterostructures, followed by ALD of 30 nm Al2O3 in order to form MOS-channel high-electron-mobility transistors (MOSc-HEMTs) on 200 mm GaN-on-Si wafers with CMOS compatible processing. The resulting transistors exhibited a normally off behavior (threshold voltage V TH = 0.4–0.6 V) and their V TH was correlated to the oxidation at the Al2O3/GaN interface, suggesting the presence of donor defects.

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Section: Resultsmentioning

confidence: 99%

Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH

Vauche

Chanuel

Martínez

et al. 2021

ACS Appl. Electron. Mater.

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“…Because the characterization of the samples by photoluminescence spectroscopy (Section 3.3) is done in a different lab, a different OP system is used for the sample preparation. In this case, the OP exposure is 10 min long and carried out using an O 2 pressure of 0.5 mbar and a forward power of 100 W. Besides the elimination of pollutants, the cleaning process also initializes the surface into a welldefined reference state, 35 which is characterized by the formation of a 0.3−2.2 nm thick GaO x capping layer. The estimation of the GaO x layer width is detailed in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

“…XPS fits with a precision of ±0.05 eV are performed using Voigt line profiles after subtraction of a Shirley background. 39 According to our previous work on GaN(0001), 35 a possible photoscreening of the surface band bending during the acquisition of the XPS signal is considered negligible here.…”

Section: Methodsmentioning

confidence: 99%

External Control of GaN Band Bending Using Phosphonate Self-Assembled Monolayers

Auzelle

Ullrich

Hietzschold

et al. 2021

ACS Appl. Mater. Interfaces

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We report on the optoelectronic properties of GaN(0001) and (11̅00) surfaces after their functionalization with phosphonic acid derivatives. To analyze the possible correlation between the acid’s electronegativity and the GaN surface band bending, two types of phosphonic acids, n-octylphosphonic acid (OPA) and 1H,1H,2H,2H-perfluorooctanephosphonic acid (PFOPA), are grafted on oxidized GaN(0001) and GaN(11̅00) layers as well as on GaN nanowires. The resulting hybrid inorganic/organic heterostructures are investigated by X-ray photoemission and photoluminescence spectroscopy. The GaN work function is changed significantly by the grafting of phosphonic acids, evidencing the formation of dense self-assembled monolayers. Regardless of the GaN surface orientation, both types of phosphonic acids significantly impact the GaN surface band bending. A dependence on the acids’ electronegativity is, however, only observed for the oxidized GaN(11̅00) surface, indicating a relatively low density of surface states and a favorable band alignment between the surface oxide and acids’ electronic states. Regarding the optical properties, the covalent bonding of PFOPA and OPA on oxidized GaN layers and nanowires significantly affects their internal quantum efficiency, especially in the nanowire case due to the large surface-to-volume ratio. The variation in the internal quantum efficiency is related to the modification of both the internal electric fields and surface states. These results demonstrate the potential of phosphonate chemistry for the surface functionalization of GaN, which could be exploited for selective sensing applications.

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“…Before the characterization of the samples by photoluminescence spectroscopy (Section II C), we use, however, a different OP system. In this case, the OP exposure is 10 min long and carried out using an O 2 pressure of 0.5 mbar and a forward power of 100 W. Besides the elimination of pollutants, the cleaning process also initializes the surface into a well-defined reference state, which is characterized by the formation of a ≤ 1 nm thick GaO x capping layer [39]. Partial hydroxylation of the surface is assumed, which favors the anchoring of phosphonic acids [40,41].…”

Section: Methodsmentioning

confidence: 99%

“…Last, we use the values reported in Ref. 39 to obtain an absolute estimate of the surface band bending after the initial OP treatment. In this way, we are able to deduce the amplitude of the GaN surface band bending after the deposition of the different SAMs.…”

Section: B Tailoring Of Surface Band Bendingmentioning

confidence: 99%

External control of GaN band bending using phosphonate self-assembled monolayers

Auzelle,

Ullrich,

Hietzschold

et al. 2020

Preprint

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Electronic properties of air-exposed GaN(11-00) and (0001) surfaces after several device processing compatible cleaning steps

Cited by 8 publications

References 61 publications

Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH

Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH

External Control of GaN Band Bending Using Phosphonate Self-Assembled Monolayers

External control of GaN band bending using phosphonate self-assembled monolayers

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Electronic properties of air-exposed GaN(11-00) and (0001) surfaces after several device processing compatible cleaning steps

Cited by 8 publications

References 61 publications

Study of an Al2O3/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage VTH

Study of an Al2O3/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage VTH

External Control of GaN Band Bending Using Phosphonate Self-Assembled Monolayers

External control of GaN band bending using phosphonate self-assembled monolayers

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Product

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Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH

Study of an Al₂O₃/GaN Interface for Normally Off MOS-Channel High-Electron-Mobility Transistors Using XPS Characterization: The Impact of Wet Surface Treatment on Threshold Voltage V_TH