A5039776698- ZnO doping and properties
- Ga2O3 and related materials
- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Electronic and Structural Properties of Oxides
- Semiconductor materials and interfaces
- Quantum Dots Synthesis And Properties
- Magnetic and transport properties of perovskites and related materials
- Nanowire Synthesis and Applications
- Graphene research and applications
- Multiferroics and related materials
- Copper-based nanomaterials and applications
- Chalcogenide Semiconductor Thin Films
- Gas Sensing Nanomaterials and Sensors
- Magnetic properties of thin films
- Advanced Semiconductor Detectors and Materials
- 2D Materials and Applications
- Machine Learning in Materials Science
- Transition Metal Oxide Nanomaterials
- Heusler alloys: electronic and magnetic properties
- Advancements in Battery Materials
- Metal and Thin Film Mechanics
Dongguk University
2012-2023
Seoul Institute
2017
Government of the Republic of Korea
2015-2017
International University of Korea
2012
Duke University
2007
Yonsei University
2004
We investigated deep-level traps formed in Al0.2Ga0.8N/GaN heterostructures grown using plasma-assisted molecular beam epitaxy and by performing deep level transient spectroscopy (DLTS). Two electron with activation energies of Ec−150 meV Ec−250 were observed, their capture cross-sections (σT) estimated to be 2.0×10−18 cm2 1.1×10−17 cm2, respectively. Different behaviors the dependence DLTS on filling pulse length confirm that originated from N vacancies dislocations. The amplitude...
Polycrystalline Cd(Zn)Te films deposited by vacuum thermal evaporation are investigated as a direct-conversion medium for x-ray detection. The use of techniques allows the preparation large-area with potential imaging high spatial resolution. Films compositions Cd1−xZnxTe (x = 0.15,0.25,0.3) were prepared to thickness 20 μm on slide glass substrates an aluminum or indium tin oxide (ITO) bottom electrode and silver top electrode, without additional charge-blocking layers (CeO2 parylene...
We report a ferromagnetic graphene field-effect transistor with band gap.
Ga 1−x Mn x N epilayers with a well-ordered ferromagnetic structure were grown on sapphire (0001) substrates, using the plasma enhanced molecular-beam epitaxy technique. Ga1−xMnxN films found to be homogeneous, and exhibit n-type conductivity ordering Curie temperature (TC) above room temperature. This was confirmed by transmission electron microscopy, x-ray diffraction, magnetometry superconducting quantum interference device. The high-temperature (T=300 K) photoluminescence (PL) spectra...
We have investigated exciton localization in binary GaN nanorods using micro- and time-resolved photoluminescence measurements. The temperature dependence of the has been measured, several phonon replicas observed at lower energy side bound to basal stacking faults (I1). By analyzing Huang-Rhys parameters as a function temperature, deduced from replica intensities, we found that excitons are strongly localized tails. lifetimes I1 I2 transitions were measured be < 100 ps due enhanced surface...
We report an efficient and controllable method to introduce p-type doping in graphene by decoration with Mn3O4 nanoparticles (NPs) on mechanically exfoliated single layer graphene. A monolayer of NPs, a diameter the range 5–10 nm, was decorated film using ex-situ method, whereas controlling coverage NPs surface, carrier concentration could be continually adjusted. The NP-decorated confirmed Raman G-band. It found that gradually adjusted up 26.09 × 1012 cm−2, 90% NPs. Dirac point pristine at...
The temperature-dependent Hall resistivity and carrier concentrations of Ga1−xMnxAs epilayers grown on (100) semi-insulating GaAs substrates by molecular beam epitaxy have been investigated in the temperature range 10–300 K. A sample with x≈4.4% shows typical insulator behavior samples x≈2.2 3.7 % show metallic behavior. model taking into account ionized impurity spin disorder scattering mechanisms was used to portray properly observed features data. value p-d exchange energy J=59.4±0.5...
The deep trap levels of AlxGa1−xN films with x in the range from 0 to 0.15 grown on c-plane sapphire substrates using rf-plasma-assisted molecular-beam epitaxy have been investigated by level transient spectroscopy measurements. Two distinct defect (denoted as Ei and Di) were observed. origins Di are associated point defects such N vacancies extended defects, threading dislocations, respectively. According Al content (x), activation energy capture cross section for ranged 0.19to0.41eV...
The thermodynamic behavior of excitonic emission properties in manganese- and zinc-codoped indium phosphide (InMnP:Zn) diluted magnetic semiconductor (DMS) layers was investigated. Compared to the InMnP:Zn DMS layer (Mn ≈ 0.06%), inhomogeneous thermal-broadening excitonic-emission line-width 0.29%) is dominant at lower temperatures. This attributed increase ionized impurity scattering from Mn ions results exciton–phonon coupling strength. As a consequence, high content can lead low...
We have observed the high-temperature (T=300K) photoluminescence (PL) spectra from free to Mn-related acceptor pair transitions in Ga1−xMnxN layers (where x≈0.2%–0.6%) grown on sapphire (0001) substrates using plasma-enhanced molecular-beam epitaxy technique. Luminescence an Mn level layer with a low content was at around E=3.08eV PL spectra. When compared undoped GaN, excitation, temperature-dependent provides convincing evidence for neutral acceptor-bound hole character. The binding energy...
The p-type InMnP:Be epilayers were prepared by the sequential growth of Mn/InP:Be bilayers using molecular-beam-epitaxy and subsequent in-situ annealing at 200–300 °C. In triple-axis x-ray diffraction patterns, samples revealed a shoulder peak indicative intrinsic InMnP. ferromagnetic transition in was observed to occur elevated temperature ∼140 K, spin-domains clearly appeared magnetic force microscopy images. improved properties are attributed increased p–d hybridation due high...
A graphene-InGaN Schottky junction has been successfully fabricated by transferring graphene layers onto n-type In<sub>0.23</sub>Ga<sub>0.77</sub>N/GaN/Al<sub>2</sub>O<sub>3</sub> substrates.