Suk-Ho Choi

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Au/Ag bilayered metal mesh with arrays of nanoholes were devised as a catalyst for metal-assisted chemical etching of silicon. The present metal catalyst allows us not only to overcome drawbacks involved in conventional Ag-based etching processes, but also to fabricate extended arrays of silicon nanowires (SiNWs) with controlled dimension and density. We(More)
We report substantially enhanced photoluminescence (PL) from hybrid structures of graphene/ZnO films at a band gap energy of ZnO (∼3.3  eV/376  nm). Despite the well-known constant optical conductivity of graphene in the visible-frequency regime, its abnormally strong absorption in the violet-frequency region has recently been reported. In this Letter, we(More)
For the application of graphene quantum dots (GQDs) to optoelectronic nanodevices, it is of critical importance to understand the mechanisms which result in novel phenomena of their light absorption/emission. Here, we present size-dependent shape/edge-state variations of GQDs and visible photoluminescence (PL) showing anomalous size dependences. With(More)
A generic process for the preparation of curved silicon nanowires (SiNWs) with ribbon-like cross sections was developed. The present synthetic approach is based on chemical etching of (100)-oriented silicon wafers in mixture solutions of HF and H(2)O(2) by using patterned thin gold films as catalyst and provides a unique opportunity for the fabrication of(More)
Intensive studies have recently been performed on graphene-based photodetectors, but most of them are based on field effect transistor structures containing mechanically exfoliated graphene, not suitable for practical large-scale device applications. Here we report high-efficient photodetector behaviours of chemical vapor deposition grown all-graphene p-n(More)
Graphene quantum dots (GQDs) have received much attention due to their novel phenomena of charge transport and light absorption/emission. The optical transitions are known to be available up to ~6 eV in GQDs, especially useful for ultraviolet (UV) photodetectors (PDs). Thus, the demonstration of photodetection gain with GQDs would be the basis for a plenty(More)
Active doping of B was observed in nanometer silicon layers confined in SiO(2) layers by secondary ion mass spectrometry (SIMS) depth profiling analysis and confirmed by Hall effect measurements. The uniformly distributed boron atoms in the B-doped silicon layers of [SiO(2) (8 nm)/B-doped Si(10 nm)](5) films turned out to be segregated into the Si/SiO(2)(More)
Formation and characterization of graphene p-n junctions are of particular interest because the p-n junctions are used in a wide variety of electronic/photonic systems as building blocks. Graphene p-n junctions have been previously formed by using several techniques, but most of the studies are based on lateral-type p-n junctions, showing no rectification(More)
Graphene field-effect transistors (GFETs) were fabricated by photolithography and lift-off processes, and subsequently heated in a rapid-thermal-annealing (RTA) apparatus at temperatures (T(A)) from 200 to 400 °C for 10 min under nitrogen to eliminate the residues adsorbed on the graphene during the GFET fabrication processes. Raman-scattering,(More)
Wafer-scale graphene/Si-nanowire (Si-NW) array heterostructures for molecular sensing have been fabricated by vertically contacting single-layer graphene with high-density Si NWs. Graphene is grown in large scale by chemical vapour deposition and Si NWs are vertically aligned by metal-assisted chemical etching of Si wafer. Graphene plays a key role in(More)