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We have developed a low-cost buried-mesa avalanche photodiode (APD) primarily targeted for 2.5-Gb/s lightwave applications. These APDs are made by a simple batch process that produces a robust and reliable device with potentially high yield and thus low cost. The entire base structure of our InGaAs-InP APD is grown in one epitaxial step and the remaining process consists of four simple steps including a mesa etch, one epitaxial overgrowth, isolation, and metallization. Buried-mesa APDs fabricated in this way show high uniform gain that rises smoothly to breakdown with increasing reverse bias. When biased to operate at a gain of 10, these unoptimized devices show dark current less than 20 nA, excess noise factor less than 5, and a 3-dB bandwidth of about 4 GHz. With a 1550-nm laser modulated at 2488 Mb/s, a maximum sensitivity of -327 dBm was obtained with an optical receiver using one such APD, without antireflection coatings. These APD's not only demonstrate excellent device characteristics but also high reliability under rigorous stress testing. No degradation was observed even after being biased near breakdown for over 2000 h at 200/spl deg/C.

An industrial magnetic separator with 0.5 m warm bore, 1 m effective length, 3.5 T central field superconducting magnet system, a high gradient reciprocating canister and corresponding slurry and control systems for kaolin clay purification has been constructed. Laboratory tests at different magnetic fields (1-3.5 T) and slurry velocities (0.5-3 cm/s) have been conducted. The results show the stable operation and the productivity of 3 t/h dry clay powder with 3.5-5 points brightness enhancement. >

Pohang Accelerator Laboratory, POSTECH have studied SRF cavity and constructed SRF test laboratory from January 2006. The first activity for SRF research was to develop SRF 3rd harmonic cavity for PLS, which cavity was done in 2006 and the cryostat are under design. The fabrication of ICHIRO cavity, which is ILC ACD cavity, is PAL's second activity related to SRF. Deep drawing, trimming and welding by electron beam for a 9-cell ICHIRO cavity were done in PAL. The polishing processes of RF surface including electro-polishing were done in KEK with collaboration. This will be tested with real beam in STF-1 of KEK in second half period of 2007. This paper reports fabrication of ICHIRO nine-cell cavities in PAL.

The technology innovation for extending the RCAT structure to the sub-70nm DRAM is presented. The new technology overcomes the problems induced by shrinkage of the RCAT structure and meets the requirements for the next generation DRAMs, such as high speed and low power performance. The technology roadmap down to the 50nm DRAM feature size of the RCAT development is presented.

Fully reliable lean-free stacked capacitor, with the meshes of the supporter made of Si/sub 3/N/sub 4/, has been successfully developed on 80nm COB DRAM application. This novel process terminates persistent problems caused by mechanical instability of storage node with high aspect ratio. With Mechanically Enhanced Storage node for virtually unlimited Height (MESH), the cell capacitance over 30fF/cell has been obtained by using conventional MIS dielectric with an equivalent 2.3nm oxide thickness. This inherently lean-free capacitor makes it possible extending the existing MIS dielectric technology to sub-70nm OCS (one cylindrical storage node) DRAMs.

It is shown that, given the magnitude specifications in the passband and stopband, the inverse Chebyshev functions require the identical order n as the Chebyshev counterparts. The phase and time-delay characteristics of the inverse Chebyshev functions as compared to Chebyshev functions are investigated. Unlike the Chebyshev or elliptic filters, the inverse Chebyshev functions possess the maximally flat magnitude at DC, and it decreases monotonically throughout the passband. This fact implies that the phase and time-delay characteristics of the inverse Chebyshev functions must be preferable to those of the Chebyshev functions. >

We have fabricated low cost avalanche photodiodes with a novel buried mesa structure in a potentially high yielding process. Receivers based on these devices show good 2.5 Gb/s system performance and promising reliability.

To determine the effectiveness of high-gradient magnetic separation (HGMS) for kaolin clay purification and coal desulfurization in China and to develop suitable technology, a superconducting HGMS facility has been constructed and put into operation. The working separation chamber is 80 mm in diameter and 400 mm in length. The magnet is wound with 0.75-mm and 0.5-mm diameter NbTi superconducting composite. The winding is compact and wax-filled. Tests prove that the magnet can operate at 5 T. Special attention has been paid to design and construction of the magnet cryostat. In the wet benefication mode, there are two separation systems available; one is an upward pumping feeding system and another is downward gravity feeding. The rate of flow and the linear velocity are 0-0.5 L/s and 0-100 cm/s, respectively. Preliminary sample test results for kaolin clay purification and coal desulfurization show the feasibility of magnetic separation. >