• Korean Journal of Materials Research
• /
• v.11 no.5
• /
• pp.419-426
• /
• 2001

The stochiometric $AgGaSe_2$ polycrystalline mixture of evaporating materials for the $AgGaSe_2$ single crystal thin film was prepared from horizontal furnace. To obtain the single crystal thin films, $AgGaSe_2$ mixed crystal and semi-insulating GaAs(100) wafer were used as source material and substrate for the Hot Wall Epitaxy (HWE) system, respectively. The source and substrate temperature were fixed at$ 630^{\circ}C$ and $420^{\circ}C$, respectively. The thickness of grown single crystal thin films is 2.1$\mu\textrm{m}$. The single crystal thin films were investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of AgGaSe$_2$ single crystal thin films measured from Hall effect by van der Pauw method are $4.89\Times10^{17}$ cm$^{-3}$ , 129cm2/V.s at 293K, respectively. From the Photocurrent spectrum by illumination of perpendicular light on the c-axis of the AgGaSe$_2$ single crystal thin film, we have found that the values of spin orbit splitting $$\Delta$S_{o}$ and the crystal field splitting $\Delta$C$_{r}$, were 0.1762eV and 0.2474eV at 10K, respectively. From the photoluminescence measurement of AgGaSe$_2$ single crystal thin film, we observed free excision (EX) observable only in high quality crystal and neutral bound exciton ($D^{o}$ , X) having very strong peak intensity. And, the full width at half maximum and binding energy of neutral donor bound excition were 8mev and 14.1meV, respectively. By Haynes rule, an activation energy of impurity was 141 meV.ion energy of impurity was 141 meV.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.8B
• /
• pp.691-700
• /
• 2006

Based on the destination IP address of incoming packets, the Internet routers determine next hops and forward packets toward final destinations through If address lookup. The bandwidth of communication links increases exponentially fast as well as the routing table size grows significant as the number of single host networks attached to the Internet increases. Since packets should be processed at wire-speed, the increased link speed reduces the processing time of a packet in routers, and hence more efficient and fast IP address lookup algorithms and architectures are required in the next generation routers. Most of the previous IP lookup schemes compare routing prefixes of shorter length first with a given input IP address. Since IP address lookup needs to find the most specific route of the given input, search continues until the longest matched prefix is found while it keeps remembering the current test matching prefix. In this paper, based on binary search on prefix length, we proposed a new IP address lookup algorithm which compares longer prefixes first. The proposed scheme is consisted of multiple tries with prefixes on leaves only. The trie composed of the longest prefixes is primarily searched whether there is a match with the given input. This processing is repeated for the trio of the next longer prefixes until there finds a match. Hence the proposed algorithm provides the fast search speed. The proposed algorithm also provides the incremental update of prefixes while the previous binary search on length scheme does not provide the incremental update because of pre-processing requirement. In this paper, we performed extensive simulations and showed the performance comparisons with related works.

• Applied Chemistry for Engineering
• /
• v.19 no.3
• /
• pp.299-303
• /
• 2008

A thermally cross-linkable polymer, poly[(2,5-dimethoxy-1,4-phenylenevinylene)-alt-(1,4-phenylenevinylene)] (Cross-PPV), was synthesized by the Heck coupling reaction. In order for the polymer to be cross-linkable, 20 mol% excess divinylbenzene was added. The chemical structure of Cross-PPV and thermally crosslinked Cross-PPV were confirmed by FT-IR spectroscopy. From the FT-IR, UV-Vis, and PL spectral data, thermally crosslinked Cross-PPV was insoluble in common organic solvents. The HOMO and LUMO energy level of thermally cross-linked Cross-PPV were estimated -5.11 and -2.56 eV, respectively, which were determined by the cyclic voltammetry and UV-Vis spectroscopy. From the energy level data, one can easily notice that thermally crosslinked Cross-PPV can be used for hole injection layer effectively. Bilayer structured device (ITO/crosslinked Cross-PPV/PM-PPV/Al) was fabricated using poly(1,4-phenylenevinylene-(4-dicyanomethylene-4H-pyran)-2,6-vinylene-1,4-phenylenevinylene-2,5-bis(dodecyloxy)-1,4-phenylenevinylene (PM-PPV) as the emitting layer, which have HOMO and LUMO energy levels of -5.44 eV and -3.48 eV, respectively. The bilayered device had much enhanced the maximum efficiency (0.024 cd/A) and luminescence ($45cd/m^2$) than those of a single layer device (ITO/PM-PPV/Al, 0.003 cd/A, $3cd/m^2$). The enhanced performance originated from that fact that cross-linked Cross-PPV facilitatse the hole injection to the emissive layer and the injected hole and electron from ITO and Al are recombined in emitting layer (PM-PPV) effectively.