Nanofabrication of Vertically Aligned 3D GaN Nanowire Arrays with Sub-50 nm Feature Sizes Using Nanosphere Lift-off Lithography

Granz, Tony; Mariana, Shinta; Hamdana, Gerry; Feng, Yuqing; Fatahilah, Muhammad Fahlesa; Puranto, Prabowo; Li, Zhi; Brand, Uwe; Prades, Joan Daniel; Peiner, Erwin; Waag, A.; Wasisto, Hutomo Suryo

doi:10.3390/proceedings1040309

Cited by 6 publications

(4 citation statements)

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“…Although inductively coupled plasma reactive ion etching (ICP-RIE) of β-Ga 2 O 3 has been recently studied with surface roughness and etch rate characterization, the etching quality is still limited compared to the GaN etching technologies , and the highest AR reported so far is only around 2.42 . In addition, the surface suffers from high energy ion induced damage, especially at increased etch rate. , On the other hand, although using the wet etching process might be able to avoid the high-energy ion induced damage caused by dry etching, a high etching temperature (∼150 °C) was typically required, − and the AR achieved was mostly below 1, which is much lower than that of wet etching of GaN. − Thus, etching techniques that can produce high AR and damage-free surface are urgently needed for this wide bandgap material.…”

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confidence: 99%

High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

et al. 2019

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β-Ga 2 O 3 , with a bandgap of ∼4.6−4.9 eV and readily available bulk substrates, has attracted tremendous interest in the wide bandgap semiconductor community. Producing high aspect ratio β-Ga 2 O 3 3D nanostructures without surface damage is crucial for nextgeneration power electronics. However, most wet etching methods can only achieve very limited aspect ratios, while dry etch usually damages the surface due to high energy ions. In this work, we demonstrate the formation of β-Ga 2 O 3 fin arrays on a (010) β-Ga 2 O 3 substrate by metalassisted chemical etching (MacEtch) with high aspect ratio and sidewall surfaces with excellent quality. The etching was found to be strongly crystal orientation dependent, and three kinds of vertical structures were formed after MacEtch. The Schottky barrier height (SBH) between Pt and various MacEtch-produced β-Ga 2 O 3 surfaces and sidewalls was found to decrease as the aspect ratio of the β-Ga 2 O 3 vertical structure increased. This could be attributed to the different amount of oxygen lost at the surface after etching, as indicated by the XPS and TEM examination. Very little hysteresis was observed in the capacitance−voltage characteristics for the 3D Pt/Al 2 O 3 /β-Ga 2 O 3 MOS capacitor structures, and the extracted interface trap density was as small as 2.73 × 10 11 cm −2 eV −1 , comparable to or lower than that for unetched planar β-Ga 2 O 3 surfaces. KEYWORDS: β-Ga 2 O 3 , metal-assisted chemical etching, high aspect ratio, XPS, Schottky barrier height, D it β-Gallium oxide (β-Ga 2 O 3 ) is considered a promising material for high-power applications due to its ultrawide band gap of 4.6−4.9 eV, 1,2 high theoretical breakdown electric field of 8 MV/cm, and reasonable 150 cm 2 /V-s electron mobility. 3 These properties lead to a 1721 Baliga's figure of merit for the powering switch and outperforms the value of SiC and GaN. 4−6 Moreover, β-Ga 2 O 3 is a wide bandgap semiconducting material with the availability of single crystalline bulk substrate and controllable n-type doping concentration over the full range of <10 14 and up to >10 20 cm −3 . 7,8 Over the past five years, many high-power β-Ga 2 O 3 applications, such as Schottky diodes, 9,10 MESFETs, 11 MOSFETs, 12−15 vertical transistors, [16][17][18]19 have been successfully demonstrated. However, the β-Ga 2 O 3 transistors published so far still suffer from low current density compared to GaN devices. To further enhance the on-current and gate control, the development of techniques for fabricating β-Ga 2 O 3 vertical structures with high aspect ratios (ARs) and smooth surfaces is essential. 3D β-Ga 2 O 3 nanostructures will also be useful for solar-blind photodetectors and sensing applications. 20,21 Although inductively coupled plasma reactive ion etching (ICP-RIE) of β-Ga 2 O 3 has been recently studied with surface

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High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

et al. 2019

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“…The depth of the etched structure can be easily controlled by adjusting the etching durations. To reach n-GaN layer, dry etching was performed for 12 min with controlled parameters [5], resulting in a trench depth of approximately 1.5 μm. Smooth n-GaN surface was highly required for better adhesion to the metal contact.…”

Section: Fabrication Methods and Resultsmentioning

confidence: 99%

Pinhole microLED Array as Point Source Illumination for Miniaturized Lensless Cell Monitoring Systems

Mariana

Scholz

et al. 2018

Eurosensors 2018

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Pinhole-shaped light-emitting diode (LED) arrays with dimension ranging from 100 μm down to 5 μm have been developed as point illumination sources. The proposed microLED arrays, which are based on gallium nitride (GaN) technology and emitting in the blue spectral region (λ = 465 nm), are integrated into a compact lensless holographic microscope for a non-invasive, label-free cell sensing and imaging. From the experimental results using single pinhole LEDs having a diameter of 90 μm, the reconstructed images display better resolution and enhanced image quality compared to those captured using a commercial surface-mount device (SMD)-based LED.

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“…In contrast, alongside nanoimprint, nanosphere lithography offers an approach that allows large-area fabrication (scalable) at a relatively low cost. Nanosphere lithography is a route that has been used to produce large-area top-down GaN NWs. − Long NWs require large nanospheres in order to have a mask that withstands the long dry etching process. However, this can impose a limitation to reduce the NW diameter if the radial etching step also leads to some axial etching.…”

Section: Introductionmentioning

confidence: 99%

High-Aspect-Ratio GaN p–i–n Nanowires for Linear UV Photodetectors

da Silva,

Biegański,

Durand

et al. 2023

ACS Appl. Nano Mater.

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Ultraviolet GaN photodetectors based on nanowires (NWs) fabricated by top-down strategies promise improved uniformity, morphology, and doping control with respect to bottom-up ones. However, exploiting the advantages of the NW geometry requires sub-wavelength NW diameters. We present fabrication of large-area sub-200 nm diameter top-down GaN p–i–n NW ultraviolet photodetectors with lengths over 2 μm produced from a planar specimen using nanosphere lithography, followed by a combination of dry and crystallographic-selective wet etching. Photocurrent measurements in single-NW devices under bias show a linear response as a function of the optical power, with increased current levels under reverse bias. The linearity proves that the drift of photogenerated carriers at the junction is the dominating photodetection mechanism, with negligible contributions from surface effects. These results demonstrate that the unique properties of NW-based photodetectors can be assessed through a scalable and low-cost fabrication process.

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Nanofabrication of Vertically Aligned 3D GaN Nanowire Arrays with Sub-50 nm Feature Sizes Using Nanosphere Lift-off Lithography

Cited by 6 publications

References 6 publications

High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

Pinhole microLED Array as Point Source Illumination for Miniaturized Lensless Cell Monitoring Systems

High-Aspect-Ratio GaN p–i–n Nanowires for Linear UV Photodetectors

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Nanofabrication of Vertically Aligned 3D GaN Nanowire Arrays with Sub-50 nm Feature Sizes Using Nanosphere Lift-off Lithography

Cited by 6 publications

References 6 publications

High Aspect Ratio β-Ga2O3 Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

High Aspect Ratio β-Ga2O3 Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

Pinhole microLED Array as Point Source Illumination for Miniaturized Lensless Cell Monitoring Systems

High-Aspect-Ratio GaN p–i–n Nanowires for Linear UV Photodetectors

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High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching

High Aspect Ratio β-Ga₂O₃ Fin Arrays with Low-Interface Charge Density by Inverse Metal-Assisted Chemical Etching