Fullerene-Incorporated Nanocomposite Resist System for Nanolithograpy

1999 ◽  
Vol 584 ◽  
Author(s):  
T. Ishii ◽  
H. Nozawa ◽  
E. Kuramochi ◽  
T. Tamamura
Keyword(s):  
High Electron Mobility Transistors ◽  
Resistance Pattern ◽  
High Electron ◽  
Positive Type ◽  
X Ray ◽  
Electron Mobility Transistors ◽  
Self Organized ◽  
Ordered Array ◽  
Lift Off ◽  
Fullerene Content

AbstractA nanocomposite resist system that incorporates sub-nm fullerene molecules ( C60 and/or C70) into a conventional resist material is proposed for nanolithograpy. Fullerene has physically and chemically resistant characteristics, and its incorporation reinforces the original resist film, leading to substantial improvements in resist performance: etching resistance, pattern contrast, mechanical strength and thermal resistance. We have prepared a system composed of a positive-type electron beam resist, ZEP520, and C60 or a C60/C70 mixture and through the fabrication of high electron mobility transistors (HEMTs), X-ray masks, and groove-grating mirrors for lasers with nanometer dimensions confirmed improved resist performance, particularly resolution improvements due to enhanced etching resistance. By making use of a characteristic unique to the nanocomposite, which is that sensitivity readily changes with the fullerene content due to a dissolution inhibiting effect of fullerene, we have constructed a fullerene-incorporated bilayer resist system for a lift-off process and have successfully fabricated a highly-ordered array of self-organized boxlike nanostructures and a mold for nanoprinting. Further, solubility enhancement by fullerene derivatives has been examined for a higher degree of fullerene incorporation and better sensitivity characteristics in future nanocomposite resist systems.

Donor passivation in pseudomorphic-high electron mobility transistors due to plasma-incorporated fluorine impurities observed using x-ray photoemission spectroscopy

2006 ◽  
Vol 21 (5) ◽  
pp. 1331-1335 ◽  
Author(s):  
Hiroyuki Uchiyama ◽  
Takeshi Kikawa ◽  
Takafumi Taniguchi ◽  
Takashi Shiota
Keyword(s):  
Electron Mobility ◽  
High Electron Mobility Transistors ◽  
Photoemission Spectroscopy ◽  
High Electron ◽  
Plasma Exposure ◽  
High Electron Mobility ◽  
X Ray ◽  
Electron Mobility Transistors ◽  
Wet Chemical ◽  
Wet Chemical Etching

To investigate the effect of plasma-incorporated fluorine on Si donors in pseudomorphic-high electron mobility transistors (P-HEMTs), we used x-ray photoemission spectroscopy to analyze three layers near the Si δ-doped layer and the Si δ-doped layer itself, in which we previously found fluorine accumulation after post-thermal annealing following fluorocarbon-based plasma exposure. For this evaluation, we developed controllable and low-speed AlGaAs wet-chemical etching using citric-acid-based wet etchant. We used it to expose one of the layers to be analyzed: one 7.5 nm above the Si δ-doped layer, one 1.5 nm above it, the δ-doped layer itself, and one 1.5 nm below it. We found that the accumulated fluorine localized in the δ-doped layer and reacted with Si donors. This is apparently the main reason for the carrier passivation in the fluorocarbon-based plasma-exposed P-HEMTs.

scholarly journals Epitaxial Lift-Off of Flexible GaN-Based HEMT Arrays with Performances Optimization by the Piezotronic Effect

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Xin Chen ◽  
Jianqi Dong ◽  
Chenguang He ◽  
Longfei He ◽  
Zhitao Chen ◽  
...  
Keyword(s):  
Low Cost ◽  
High Electron Mobility Transistors ◽  
Electrical Performance ◽  
Full Potential ◽  
High Electron ◽  
Electron Mobility Transistors ◽  
Piezotronic Effect ◽  
Lift Off ◽  
Gan Heterostructure ◽  
Polyethylene Terephthalate Substrate

AbstractHigh-electron-mobility transistors (HEMTs) are a promising device in the field of radio frequency and wireless communication. However, to unlock the full potential of HEMTs, the fabrication of large-size flexible HEMTs is required. Herein, a large-sized (> 2 cm2) of AlGaN/AlN/GaN heterostructure-based HEMTs were successfully stripped from sapphire substrate to a flexible polyethylene terephthalate substrate by an electrochemical lift-off technique. The piezotronic effect was then induced to optimize the electron transport performance by modulating/tuning the physical properties of two-dimensional electron gas (2DEG) and phonons. The saturation current of the flexible HEMT is enhanced by 3.15% under the 0.547% tensile condition, and the thermal degradation of the HEMT was also obviously suppressed under compressive straining. The corresponding electrical performance changes and energy diagrams systematically illustrate the intrinsic mechanism. This work not only provides in-depth understanding of the piezotronic effect in tuning 2DEG and phonon properties in GaN HEMTs, but also demonstrates a low-cost method to optimize its electronic and thermal properties.

scholarly journals Substrate Effects on the Electrical Properties in GaN-Based High Electron Mobility Transistors

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1414
Author(s):  
Sung-Jae Chang ◽  
Kyu-Jun Cho ◽  
Sang-Youl Lee ◽  
Hwan-Hee Jeong ◽  
Jae-Hoon Lee ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Sapphire Substrate ◽  
Electron Mobility ◽  
High Electron Mobility Transistors ◽  
High Electron ◽  
Back Side ◽  
High Electron Mobility ◽  
Electron Mobility Transistors ◽  
Cu Film ◽  
Lift Off

We report the electrical characteristics of GaN-based high electron mobility transistors (HEMTs) operated on various substrates/films. For the detailed investigation and comparison of the electrical properties of GaN-based HEMTs according to the substrates/films, GaN-based HEMTs were processed using 4-inch sapphire substrates and separated from their original substrates through the laser lift-off technique. The separated AlGaN/GaN films including processed GaN-based HEMTs were bonded to AlN substrate or plated with a 100 µm-thick Cu at the back-side of the devices since AlN substrate and Cu film exhibit higher thermal conductivity than the sapphire substrate. Compared to the sapphire substrate, DC and RF properties such as drain current, transconductance, cut-off frequency and maximum oscillation frequency were improved, when GaN-based HEMTs were operated on AlN substrate or Cu film. Our systematic study has revealed that the device property improvement results from the diminishment of the self-heating effect, increase in carrier mobility under the gated region, and amelioration of sheet resistance at the access region. C(V) and pulse-mode stress measurements have confirmed that the back-side processing for the device transfer from sapphire substrate onto AlN substrate or Cu film did not induce the critical defects close to the AlGaN/GaN hetero-interface.

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