• Proceedings of the Materials Research Society of Korea Conference
• /
• 2005.05a
• /
• pp.73-73
• /
• 2005

• Proceedings of the Korean Vacuum Society Conference
• /
• 2005.02a
• /
• pp.101-101
• /
• 2005

• Proceedings of the Korean Vacuum Society Conference
• /
• 2009.08a
• /
• pp.227-227
• /
• 2009

• Proceedings of the Korean Vacuum Society Conference
• /
• 2009.08a
• /
• pp.411-411
• /
• 2009

• 한국전자현미경학회:학술대회논문집
• /
• 2001.11a
• /
• pp.92-96
• /
• 2001

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.22 no.1
• /
• pp.34-40
• /
• 1985

An investigation has been made on the growth phenomena of epitaxial layer and polysilicon from SiH2 Cl2 in H2 and the etch phenomena of them from HCI in H2, at the system pressures of 1.0 atm (atmospheric process) and 0.1 attn (reduced pressure process). From the experimental equations for the growth rates and etch rates. the relevant process conditions for the selective epitaxy are predicted for the case of using mixtures of SiH2Cl2 and HCI in H2. As a result, it is found that selective epitaxial growth region exists in the concentration range investigated for the reduced pressure process but it does not for the atmospheric Process. This is due to the differences in the growth rates and etch rates at atmospheric and reduced pressure.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.562-565
• /
• 2013

The high purity Al foil, which has an enlarged surface area by electrochemical etching process, has been used as an anode for an aluminum electrolytic capacitor. Etch pits are randomly distributed on the surface because of the existence of surface irregularities such as impurity and random nucleation of pits. Even though a large surface area was formed on the tunnel-etched Al, its applications to various fields were limited due to non-uniform tunnel morphologies. In this work, the selective electrochemical etching of aluminum was carried out by using a patterned mask fabricated by photolithographic method. The formation of etch pits with uniform distribution has been demonstrated by the optimization of experimental conditions such as current density and etching solution temperature.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.48-48
• /
• 2011

We have developed a chemically-driven top-down approach using vapor phase HCl to form various GaN nanostructures and successfully demonstrated dislocation-free and strain-relaxed GaN nanostructures without etching damage formed by a selective dissociation method. Our approach overcomes many limitations encountered in previous approaches. There is no need to make a pattern, complicated process, and expensive equipment, but it produces a high-quality nanostructure over a large area at low cost. As far as we know, this is the first time that various types of high-quality GaN nanostructures, such as dot, cone, and rod, could be formed by a chemical method without the use of a mask or pattern, especially on the Ga-polar GaN. It is well known that the Ga-polar GaN is difficult to etch by the common chemical wet etching method because of the chemical stability of GaN. Our chemically driven GaN nanostructures show excellent structure and optical properties. The formed nanostructure had various facets depending on the etching conditions and showed a high crystal quality due to the removal of defects, such as dislocations. These structure properties derived excellent optical performance of the GaN nanostructure. The GaN nanostructure had increased internal and external quantum efficiency due to increased light extraction, reduced strain, and improved crystal quality. The chemically driven GaN nanostructure shows promise in applications such as efficient light-emitting diodes, field emitters, and sensors.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.2 no.2
• /
• pp.93-101
• /
• 2002

We have proposed and fabricated two lateral type field emission diodes, poly-Si emitter by utilizing the local oxidation of silicon (LOCOS) and GaN emitter using metal organic chemical vapor deposition (MOCVD) process. The fabricated poly-Si diode exhibited excellent electrical characteristics such as a very low turn-on voltage of 2 V and a high emission current of $300{\;}\bu\textrm{A}/tip$ at the anode-to-cathode voltage of 25 V. These superior field emission characteristics was speculated as a result of strong surface modification inducing a quasi-negative electron affinity and the increase of emitting sites due to local sharp protrusions by an appropriate activation treatment. In respect, two kinds of procedures were proposed for the fabrication of the lateral type GaN emitter: a selective etching method with electron cyclotron resonance-reactive ion etching (ECR-RIE) or a simple selective growth by utilizing $Si_3N_4$ film as a masking layer. The fabricated device using the ECR-RIE exhibited electrical characteristics such as a turn-on voltage of 35 V for $7\bu\textrm{m}$ gap and an emission current of~580 nA/l0tips at anode-to-cathode voltage of 100 V. These new field emission characteristics of GaN tips are believed to be due to a low electron affinity as well as the shorter inter-electrode distance. Compared to lateral type GaN field emission diode using ECR-RIE, re-grown GaN emitters shows sharper shape tips and shorter inter-electrode distance.

• Journal of Powder Materials
• /
• v.20 no.2
• /
• pp.120-124
• /
• 2013

This study is carried out to develop the new process for the fabrication of ultra-fine electrodes on the flexible substrates using superhydrophobic effect. A facile method was developed to form the ultra-fine trenches on the flexible substrates treated by plasma etching and to print the fine metal electrodes using conductive nano-ink. Various plasma etching conditions were investigated for the hydrophobic surface treatment of flexible polyimide (PI) films. The micro-trench on the hydrophobic PI film fabricated under optimized conditions was obtained by mechanical scratching, which gave the hydrophilic property only to the trench area. Finally, the patterning by selective deposition of ink materials was performed using the conductive silver nano-ink. The interface between the conductive nanoparticles and the flexible substrates were characterized by scanning electron microscope. The increase of the sintering temperature and metal concentration of ink caused the reduction of electrical resistance. The sintering temperature lower than $200^{\circ}C$ resulted in good interfacial bonding between Ag electrode and PI film substrate.