GaN metal-oxide-semiconductor diodes with molecular beam epitaxy-Al2O3 as a template followed by atomic layer deposition growth

Chang, Yang-Hua; Chiu, H. C.; Chang, W. H.; Kwo, J.; Tsai, Chieh Chih; Hong, J. M.; Hong, M.

doi:10.1016/j.jcrysgro.2008.11.011

Cited by 17 publications

(7 citation statements)

References 18 publications

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“…Multiple studies on Ga-polar GaN have shown good surface treatments prior to ALD of a high-k oxide film is essential. For instance, Chang et al 22 used an HCl solution cleaning method but residual Cl was detected on the GaN surface, causing an increase of interface traps. Diale et al 23 used an aqueous solution of (NH 4 ) 2 S to clean the GaN surface, producing low C and O concentration and a low the root mean square (RMS) roughness.…”

mentioning

confidence: 99%

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

Wei

Hossain

Briggs

et al. 2014

ECS J. Solid State Sci. Technol.

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Nitrogen-polar gallium nitride offers several advantages over Ga-polar GaN for high frequency-high power electronic devices, but its processing has not been fully developed. Here we report on a systematic study of the effect of surface pretreatments on N-polar GaN for metal oxide semiconductor capacitors (MOSCAPs). Bulk n-type GaN (0001) substrates were prepared with a variety of treatments including: HF; HCl; base-piranha; H 2 plasma; and no pretreatment for comparison. Then 14nm thick Al 2 O 3 layers were deposited by atomic layer deposition (ALD). Both the original surfaces of GaN and ALD films were characterized by atomic force microscopy (AFM). MOSCAPs were fabricated and characterized by capacitance-voltage (C-V) and current voltage (I-V) measurements. The surface morphology and electrical performance was greatly affected by the pretreatments due to the reactive nature of N-polar GaN. The MOSCAP fabricated on GaN as-received with no additional preparation had the best performance including the smallest hysteresis (0.03V), lowest leakage current density (2.09 × 10 −8 A/cm 2 at +4V) and total trap density (2.47 × 10 10 cm −2 eV −1 ). This was correlated to the smoothest surface morphology (0.23 nm). The wide bandgap semiconductor gallium nitride (GaN) is of great interest not only for optoelectronic devices such as blue LEDs, 1 laser diodes, 2 and UV detectors, but also for highly efficient electronic devices operating at high frequency, temperature and power. After years of development, Ga-polar GaN based high electron mobility transistors (HEMTs) have been demonstrated with excellent performance and high RF output power.3,4 Increasing the maximum frequency by scaling down the GaN HEMT dimensions to reduce electron transit time, establishing control of the contact resistance and capacitive elements are critically important to prevent device delay times and to achieve the best possible device performance.5 Nitrogen-polar GaN has potential advantages over Ga-polar GaN for high-frequency applications due to its low contact resistance and a natural back barrier to improve electron confinement.6-8 For example, an extremely low contact resistance of 23 -μm was reported by Mishra et al. 9 To date, most of the N-polar GaN HEMT devices employ structures with a Schottky barrier as the gate contact. 6,10,11 However, a metaloxide-semiconductor structure is preferred, as it provides a higher input impedance, larger gate voltage swings, and lower gate leakage currents. 12,13 Aluminum oxide (Al 2 O 3 ) is an excellent gate dielectric for IIInitride based devices due to its large bandgap (7∼9 eV), relatively high dielectric constant (∼9) and high thermal stability (up to 1000• C). 14-20 Precise control of this dielectric's thickness is necessary to maintain the aspect ratio between the gate length and the oxide thickness for good high frequency performance. Atomic layer deposition (ALD) offers excellent thickness control for the deposition of such dielectrics, 21 but the initial condition of the substrate surface is crucia...

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mentioning

confidence: 99%

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

Wei

Hossain

Briggs

et al. 2014

ECS J. Solid State Sci. Technol.

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“…In this work, crystalline Al 2 O 3 was formed on GaN substrate during PDA at 800 °C in oxygen (O 2 ) ambient. A better J–E characteristic of the crystalline Al 2 O 3 is shown in Figure in comparison with replotted J–E characteristics of formerly reported Al 2 O 3 /GaN ,− structure using linear approximation method. Besides, the obtained J–E characteristic in this work has surpassed the J–E characteristics demonstrated by majority reported gate oxide materials .…”

Section: Introductionmentioning

confidence: 69%

Surface Passivation of Gallium Nitride by Ultrathin RF-Magnetron Sputtered Al₂O₃ Gate

Quah

Cheong

2013

ACS Appl. Mater. Interfaces

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An ultrathin RF-magnetron sputtered Al2O3 gate on GaN subjected to postdeposition annealing at 800 °C in O2 ambient was systematically investigated. A cross-sectional energy-filtered transmission electron microscopy revealed formation of crystalline Al2O3 gate, which was supported by X-ray diffraction analysis. Various current conduction mechanisms contributing to leakage current of the investigated sample were discussed and correlated with metal-oxide-semiconductor characteristics of this sample.

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“…A variety of thin films can be deposited utilizing ALD deposition with high density and low impurity at a low deposition temperature. The Al 2 O 3 and HfO 2 dielectrics are common insulators grown using ALD system and have been applied in AlGaN/GaN MOS-HEMTs (Park et al, 2004;Ye et al, 2005;Wu et al, 2006;Kim et al, 2007;Medjdoub et al, 2007;Yue et al, 2008;Feng et al, 2009;Chang et al, 2009). The qualities of Al 2 O 3 films gauged by several important figures of merit including uniformity, defect density and stoichiometric ratio of the deposited films, are comparably better, when ALD is chosen over the other deposition methods such as sputtering and electron-beam deposition methods.…”

Section: Atomic Layer Deposition (Ald) Deposition Methodsmentioning

confidence: 99%

GaN-based Metal-Oxide-Semiconductor Devices

Lee¹

2010

Semiconductor Technologies

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GaN metal-oxide-semiconductor diodes with molecular beam epitaxy-Al2O3 as a template followed by atomic layer deposition growth

Cited by 17 publications

References 18 publications

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

Surface Passivation of Gallium Nitride by Ultrathin RF-Magnetron Sputtered Al₂O₃ Gate

GaN-based Metal-Oxide-Semiconductor Devices

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GaN metal-oxide-semiconductor diodes with molecular beam epitaxy-Al2O3 as a template followed by atomic layer deposition growth

Cited by 17 publications

References 18 publications

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al2O3

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al2O3

Surface Passivation of Gallium Nitride by Ultrathin RF-Magnetron Sputtered Al2O3 Gate

GaN-based Metal-Oxide-Semiconductor Devices

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Product

Resources

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A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

A Comparison of N-Polar () GaN Surface Preparations for the Atomic Layer Deposition of Al₂O₃

Surface Passivation of Gallium Nitride by Ultrathin RF-Magnetron Sputtered Al₂O₃ Gate