• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.19-20
• /
• 2006

Two methods that can reduce reflectance in solar cells are surface texturing and anti-reflection coating. Wet chemical etching is a typical method that surface texturing of multi-crystalline silicon. Wet chemical etching methods are the acid texturization of saw damage on the surface of multi-crystalline silicon or double-step chemical etching after KOH saw damage removal too. These methods of surface texturing are realized by chemical etching in acid solutions HF-$HNO_3$-$H_2O$. In this solutions we can reduce reflectance spectra by simple process etching of multi-crystalline silicon surface. We have obtained reflectance of 27.19% m 400~1100nm from acidic chemical etching after KOH saw damage removal. This result is about 7% less than just saw damage removal substrate. The surface morphology observed by microscope and scanning electron microscopy (SEM).

• Journal of the Semiconductor & Display Technology
• /
• v.13 no.2
• /
• pp.29-35
• /
• 2014

In this study general solar cell production process was complemented, with research on improvement of solar cell efficiency through surface structure and thermal annealing process. Firstly, to form the pyramid structure, the saw damage removal (SDR) processed surface was undergone texturing process with reactive ion etching (RIE). Then, for the formation of smooth pyramid structure to facilitate uniform doping and electrode formation, the surface was etched with HND(HF : HNO3 : D.I. water=5 : 100 : 100) solution. Notably, due to uniform doping the leakage current decreased greatly. Also, for the enhancement and maintenance of minority carrier lifetime, antireflection coating thermal annealing was done. To maintain this increased lifetime, front electrode was formed through Au plating process without high temperature firing process. Through these changes in two processes, the leakage current effect could be decreased and furthermore, the conversion efficiency could be increased. Therefore, compared to the general solar cell with a conversion efficiency of 15.89%, production of high efficiency solar cell with a conversion efficiency of 17.24% was made possible.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1448-1449
• /
• 2006

Pb(Zr,Ti)$O_3$ is one of the most attractive ferroelectric materials for realizing the FeRAM due to its higher remanant polarization and the ability to withstand higher coercive fields. Generally, the ferroelectric materials were patterned by a plasma etching process for high-density FeRAM. The applicable possibility of CMP process to pattern Pb(Zr,Ti)$O_3$ instead of plasma etching process was investigated in our previous study for improvement of an angled sidewall which prevents the densification of ferroelectric memory and is apt to receive the plasma damage. Our previous study showed that good removal rate with the excellent surface roughness compared to plasma etching process were obtained by CMP process for the patterning of Pb(Zr,Ti)$O_3$. The suitable selectivity to TEOS without any damage to the structural property of Pb(Zr,Ti)$O_3$ was also guaranteed. In this study, the removal mechanism of $Pb_{1.1}(Zr_{0.52}Ti_{0.48})O_3$ coated by sol-gel method was investigated. Surface analysis of polished specimens at the best and worst conditions was carried out by XPS.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.139.2-139.2
• /
• 2013

6" Multi-crystal Silicon wafer has etched suing a remote - type RF Dielectric barrier discharge (RF DBD) at atmospheric pressure. DBD source is composed of Al electrode and coated Al2O3 dielectric as function of Ar/NF3 gas combination and input power used 13.56 MHz power supply. Ar gas flow rate is changed from 2 to 10 Slm, and NF3 flow rate is changed from 0.2~1 slm. At the result, NF3 flow rate Si etching rate also increase whit the increasing of NF3 flow rate But at 2 slm etching rate was decrease. In this experience, Max etching rate is 2.3 ${\mu}m/min$ when the scan time is 45 sec.

• Korean Journal of Metals and Materials
• /
• v.46 no.12
• /
• pp.835-840
• /
• 2008

Texturing for crystalline silicon solar cells is one of the important techniques to increase conversion efficiency by effective photon trapping. Generally, incoming wafers or alkali etched wafers are used for texturing. From this conventional etching process, $7{\sim}10{\mu}m$-sized random pyramids are formed. In this study, acid etching for removal of saw damages was practiced before texturing. This improved the resulting surface morphology, which consisted of $2{\sim}4{\mu}m$-sized pyramids. Because these pyramids covered the surface much more extensively, we obtained reduction of optical losses on the surface. In order to compare with conventional texturing, FE-SEM is used for observing surface morphology and reflectance data is analyzed by UV-VIS spectrophotometer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.12
• /
• pp.1271-1276
• /
• 2004

Two-dimensionally arrayed nanocolumn lattices were fabricated by using double-exposure laser holographic method. The hexagonal lattice was formed by rotating the sample with 60 degree while the square lattice by 90 degree before the second laser-exposure. The reactive ion etching for a typical time of 30 min using CH$_4$/H$_2$ plasma enhanced the aspect-ratio by more than 1.5 with a slight increase of the bottom width of columns. The etch-damage was observed by photoluminescence (PL) spectroscopy which was removed by the wet chemical etching using HBr/$H_2O$$_2$/$H_2O$ solution, leading into the enhanced PL intensities of the PCs.

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.101-102
• /
• 2006

PZT thin films, which are the representative ferroelectric materials in ferroelectric random access memory (FRAM), have some serious problem such as the imprint, retention and fatigue which ferroelectric properties are degraded by repetitive polarization. BL T thin film capacitors were fabricated by plasma etching, however, the plasma etching of BLT thin film was known to be very difficult. In our previous study, the ferroelectric materials such as PZT and BLT were patterned by chemical mechanical polishing (CMP) using damascene process to top electrode/ferroelectric material/bottom electrode. It is also possible to pattern the BLT thin film capacitors by CMP, however, the CMP damage was not considered in the experiments. The properties of BLT thin films were changed by the change of polishing pressure although the removal rate was directly proportional to the polishing pressure in CMP process.

• Korean Journal of Materials Research
• /
• v.20 no.12
• /
• pp.649-653
• /
• 2010

In this paper, double texturization of multi crystalline silicon solar cells was studied with laser and reactive ion etching (RIE). In the case of multi crystalline silicon wafers, chemical etching has problems in producing a uniform surface texture. Thus various etching methods such as laser and dry texturization have been studied for multi crystalline silicon wafers. In this study, laser texturization with an Nd:$YVO_4$ green laser was performed first to get the proper hole spacing and $300{\mu}m$ was found to be the most proper value. Laser texturization on crystalline silicon wafers was followed by damage removal in acid solution and RIE to achieve double texturization. This study showed that double texturization on multi crystalline silicon wafers with laser firing and RIE resulted in lower reflectance, higher quantum yield and better efficiency than that process without RIE. However, RIE formed sharp structures on the silicon wafer surfaces, which resulted in 0.8% decrease of fill factor at solar cell characterization. While chemical etching makes it difficult to obtain a uniform surface texture for multi crystalline silicon solar cells, the process of double texturization with laser and RIE yields a uniform surface structure, diminished reflectance, and improved efficiency. This finding lays the foundation for the study of low-cost, high efficiency multi crystalline silicon solar cells.

• The Journal of Advanced Prosthodontics
• /
• v.6 no.4
• /
• pp.295-301
• /
• 2014

PURPOSE. Numerous methods were used to etch the fiber posts to improve its bonding to root canal dentin. Our aim was to evaluate the efficacy of 37% phosphoric acid in etching fiber posts in comparison with 24% hydrogen peroxide. MATERIALS AND METHODS. Ninety human maxillary central incisors were taken and post space preparation was done. Ninety fiber posts were taken and divided into three groups (n=30) based on the surface treatment they received ($H_3PO_4$, $H_2O_2$, distilled water) and each group was further divided (n=10) based on the time period of application (15 seconds, 30 seconds, 60 seconds). All the posts were luted into canals using Rely X UniCem-2. Each tooth was then sectioned into six slices and subjected to push out test. Data obtained was subjected to statistical analysis at P<.05. The surface topography was evaluated using scanning electron microscopy. RESULTS. Highest bond strength values were noted in 15 seconds etched phosphoric acid group and 60 seconds etched hydrogen peroxide group with no significant difference between two groups. Surface topography revealed complete epoxy layer removal with no damage to its structural integrity in those groups. CONCLUSION. $H_3PO_4$ etching for a period of 15 seconds is an effective alternative in improving the adhesion of fiber post to root dentin.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.2
• /
• pp.41-47
• /
• 1999

In this paper, we report 3D-simulations of a plasma etching process by employing cell-removal algorithm takes into account the mask shadow effect os well as spillover errors. The developed simulator haas an input interface to take not only an analytic form but a Monte Carlo distribution of the ions. The graphic user interface(GUI) was also built into the simulator for UNIX environment. To demonstrate the capability of 3D-SURFILER(SURface proFILER), we have simulated for a typical contact hole structure with 36,000($30{\times}40{\times}30$) cells, which takes about 20 minutes with 10 Mbytes memory on sun ultra sparc 1. as an exemplary case, we calculated the etch profile during the reactive ion etching(RIE) of a contact hole wherein the aspect ratio is 1.57. Furthermore, we also simulated the dependence of a damage parameter and the evolution of topography as a function of the chamber pressure and the incident ion flux.