Chang Hyun Jeong

High-Rate Dry Etching of ZnO in BCl3/CH4/H2 Plasmas

High-rate dry etching characteristics of aluminum-doped zinc oxide (AZO) have been investigated in inductively coupled plasma (ICP) using BCl3/CH4/H2 plasma chemistry. Etch rates were measured as a function of BCl3 flow rate in BCl3/CH4/H2 mixture and dc-bias voltage. Measurement of etch rate, and etched sidewall profile were performed using a stylus profilometer and scanning electron microscopy, respectively. The highest AZO etch rate about 310 nm/min, could be obtained near 80% BCl3 and at dc-bias voltage of -350 V.

Deposition of SiO2 by Plasma Enhanced Chemical Vapor Deposition as the Diffusion Barrier to Polymer Substrates

SiO2 thin films were deposited at the temperatures <150°C by plasma enhanced chemical vapor deposition (PECVD) using a tetraethylorthosilicate (TEOS)/N2/O2 gas mixture, and the physical and chemical characteristics as well as the characteristics as a transparent diffusion barrier to H2O were investigated. Using a gas combination of TEOS(40 sccm)/O2(500 sccm)/N2(100 sccm) at source power of 500 W and dc bias voltage of -350 V, SiO2 with a stoichometric composition of SiO2 and a smooth surface similar to the substrate could be deposited. When a multilayer diffusion barrier composed of parylene(800 nm)/SiO2(100 nm)/parylene(800 nm)/SiO2(100 nm)/parylene(800 nm) was formed on a polyethersulfone (PES) substrate, the water vapor transmission rate (WVTR) of the substrate was decreased from 54.1 to 0.3 gm/(m2day).

A Study of Sapphire Etching Characteristics Using BCl3-based Inductively Coupled Plasmas

Cl2, HCl, and HBr added BCl3-based inductively coupled plasmas were used to etch (0001) sapphire wafers and their etch characteristics were investigated. The plasma characteristics were monitored in-situ by optical emission spectroscopy and a Langmuir probe. A photoresist was used as the etch mask and an etch selectivity greater than 1 with the etch rate of 3800 ?/min could be obtained with 20%HCl/80%BCl3. The most anisotropic etch profile could be observed in 10%HBr/90%BCl3.

Study on the O2 Plasma Treatment of Indium Tin Oxide for Organic Light Emitting Diodes Using Inductively Coupled Plasma

In this study, the effect of O2 inductively coupled plasma (ICP) conditions for the indium tin oxide (ITO) surface treatment on the organic light emitting diode (OLED) device performances were investigated. By the O2 plasma treatment of ITO glass, better OLED device performances such as a lower turn-on voltage, a higher luminescence, and a higher power efficiency could be obtained and the use of lower oxygen pressure and higher ICP power improved the device properties further. DC-biasing of the ITO glass substrate degraded the device properties. The use of lower oxygen pressure and higher ICP power increased the densities of O2+ and O* in the plasma, and the plasma-treated ITO surface showed a lower carbon, a higher O/(Sn+In), and a higher Sn4+/In for the condition of lower oxygen pressure and higher ICP power. The improved OLED device properties with the ITO treated at the higher ICP power and the lower pressure appear to be from the increased hole injection to the OLED materials by decreasing the resistance of ITO and by increasing the work function of the ITO.

Characteristics of Organic Light-Emitting Devices by the Surface Treatment of Indium Tin Oxide Surfaces Using Atmospheric Pressure Plasmas

This study examined the effects of a He/O2 and He/SF6 atmospheric pressure plasma surface treatment of indium tin oxide (ITO) glass on the ITO surface and electrical characteristics of organic light emitting diodes (OLEDs). The OLEDs composed of ITO glass/2-TNATA/NPD/Alq3/LiF/Al showed better electrical characteristics, such as lower turn-on voltage, higher power efficiency, etc., after the He/O2 or He/SF6 plasma treatment. The He/SF6 treatment resulted in superior electrical characteristics compared with the He/O2 treatment. The electrical improvement as a result of the He/SF6 and He/O2 plasma treatments is related to the decrease in the carbon and Sn4+ concentration on the ITO surface and fluorine doping of the ITO possibly indicating a change in the work function as a result of the treatments.

Characteristics of a Multilayer SiOx(CH)yNz Film Deposited by Low Temperature Plasma Enhanced Chemical Vapor Deposition Using Hexamethyldisilazane/Ar/N2O

SiOx(CH)yNz films were deposited at room temperature using plasma enhanced chemical vapor deposition (PECVD) with a gas mixture of hexamethyldisilazane [HMDS, Si2NH(CH3)6]/Ar/N2O. The characteristics of those films with increasing N2O were investigated. When no N2O was used, the film showed organic characteristics with a Si/O composition ratio of 2 and a large concentration of –CHx and N–H in the deposited film. However, with increasing N2O flow rate, oxygen-rich and transparent SiO2-like inorganic thin films could be obtained with a Si/O composition ratio of 0.5 and a lower –CHx and N–H in the deposited film. By turning on-and-off the N2O gas flow during SiOx(CH)yNz deposition, a multi-layer thin film consisting of an organic Si(CH)x-like film/inorganic SiO2-like thin film, which can be applied to the thin film passivation for organic devices could be successfully deposited.

High Efficiency White Organic Light-Emitting Diodes from One Emissive Layer

In this study, two-wavelength white organic light-emitting devices (WOLEDs) were fabricated using a single doped layer, which was obtained by forming a recombination zone in a single emissive layer. In this emissive layer, both blue emission and yellow emission were obtained using a 4,4-bis(2,2-diphenylethen-1-yl)biphenyl (DPVBi) host doped with a red fluorescent dye, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB). The white light resulted from the excitation in this single emissive layer by controlling the concentration of fluorescent dye in the emissive layer. In addition, a higher efficiency could be obtained using organic layers/Li/Al in the WOLED structure instead of organic layers/LiF/Al. The electroluminescent (EL) spectrum of the device was not sensitive to the driving voltage of the device. The obtained WOLEDs showed a maximum luminance of approximately 64,200 cd/m2 and the device began to emit light (at luminance of 0.1 cd/m2) at 3.4 V. At a luminance of approximately 100 cd/m2, the external quantum and the power efficiencies were 2.47% and 4.27 lm/W, respectively.

Effect of Indium-Oxide Deposited Using an Oxygen Ion-Beam-Assisted-Deposition to Top-Emitting Organic Light-Emitting Diodes

Indium oxide thin films have potential applications as cathodes in top-emitting organic light-emitting diodes (TEOLEDs). This study examined the characteristics of transparent conducting indium oxide (IO) films deposited by an oxygen ion-beam-assisted-deposition (IBAD) as a function of the applied oxygen ion energy (Va). When TEOLED devices consisting of glass/Ag (100 nm)/ITO (125 nm)/2-TNATA (30 nm)/NPB (15 nm)/Alq3 (55 nm)/LiF (1 nm)/Al (2 nm)/Au (20 nm)/IO (100 nm) were fabricated at a lower Va, a lower turn-on voltage was observed even though the maximum luminance (32,000 cd/m2) was similar one another. A Va of approximately +50 V produced an IO film with a resistivity of 8.5×10-4 Ωcm and a transmittance of 85%. The definition (I–V) characteristics of TEOLED devices with a cathode layer of Al (2 nm)/Au (20 nm)/IO (100 nm) were similar to the device fabricated with Al (2 nm)/Au (20 nm) only.

Top-Emitting Organic Light-Emitting Diodes Using Cs/Al/Ag Cathodes

A semi-transparent cathode composed of Cs (0.5 nm)/Al (2.0 nm)/Ag (20 nm) at the wavelength of 515 nm exhibited the transmittance of 52% and the reflectance of 46%, respectively. The top-emitting device with the glass/Ag (100 nm)/tin-doped indium oxide (ITO, 125 nm)/4,4,4-tris[2-naphthylphenyl-1-phenylamino]triphenylamine (2-TNATA, 30 nm)/4,4-bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl (NPB, 15 nm)/tris(8-quinolinolato) aluminum(III) (Alq3, 55 nm)/Cs (0.5 nm)/Al (2 nm)/Ag (20 nm)/Alq3 (52 nm) structure showed the maximum luminance of 77,200 cd/m2. Also, the external quantum efficiency and the power efficiency at about 1,000 cd/m2 were 1.9% and 2.5 lm/W, respectively. It shows about 2 times higher luminous efficiency, compared to the same device structure having lithium fluoride instead of cesium.

Device Performance of the Top-Emitting Organic Light-Emitting Diodes Using the Ba/Au/Indium Tin Oxide Cathode System with Long Skin Depth

This paper reports the favorable performance of a top-emitting organic light-emitting diode (TEOLED) using a Ba/Au/indium tin oxide (ITO) cathode. A cathode with a Ba layer and a long skin depth of 44.1 nm not only prevented damage to the underlying organic layers from ion bombardment during ITO sputtering, but also improved the light out-coupling of devices by increasing the transmittance. With increasing Ba thickness, the turn-on voltage and leakage current of the devices were lower than of those without Ba. The Ba layer in the cathode enhanced the optical characteristics of the devices by the balanced carrier injection.