In JoVE (1)
Articles by Gil Ju Lee in JoVE
Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition Young Jin Yoo1, Gil Ju Lee1, Kyung-In Jang2, Young Min Song1 1School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, 2Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.
Other articles by Gil Ju Lee on PubMed
Ultra-thin Films with Highly Absorbent Porous Media Fine-tunable for Coloration and Enhanced Color Purity Nanoscale. Mar, 2017 | Pubmed ID: 28045180 We demonstrate ultra-thin, fine-tunable optical coatings with enhanced color purity based on highly absorbent porous media on a metal substrate. We show that the color range provided by these ultra-thin film coatings can be extended by making the absorptive dielectric layer porous. Oblique angle deposition (OAD) of a thin (10-25 nm) germanium (Ge) film by e-beam evaporation onto a thick gold substrate yields controlled porosity. Reflectance spectra and color representations from both calculations and experiments verify the enhancement of resonance tunability and color purity in the nano-tailored coatings. Angle independent reflection properties, and the applicability of such porous Ge on various metal substrates, indicate the strength of these concepts.
Parametric Optimization of Lateral NIPIN Phototransistors for Flexible Image Sensors Sensors (Basel, Switzerland). Aug, 2017 | Pubmed ID: 28767076 Curved image sensors, which are a key component in bio-inspired imaging systems, have been widely studied because they can improve an imaging system in various aspects such as low optical aberrations, small-form, and simple optics configuration. Many methods and materials to realize a curvilinear imager have been proposed to address the drawbacks of conventional imaging/optical systems. However, there have been few theoretical studies in terms of electronics on the use of a lateral photodetector as a flexible image sensor. In this paper, we demonstrate the applicability of a Si-based lateral phototransistor as the pixel of a high-efficiency curved photodetector by conducting various electrical simulations with technology computer aided design (TCAD). The single phototransistor is analyzed with different device parameters: the thickness of the active cell, doping concentration, and structure geometry. This work presents a method to improve the external quantum efficiency (EQE), linear dynamic range (LDR), and mechanical stability of the phototransistor. We also evaluated the dark current in a matrix form of phototransistors to estimate the feasibility of the device as a flexible image sensor. Moreover, we fabricated and demonstrated an array of phototransistors based on our study. The theoretical study and design guidelines of a lateral phototransistor create new opportunities in flexible image sensors.