A 1/4-inch 380 k pixel IT-CCD image sensor employing gate-assisted punchthrough read-out mode

A newly developed 1/4-inch 380 k pixel IT-CCD image sensor features a novel cell structure in which signal charges are read out from a photodiode (PD) to a vertical-CCD (V-CCD) in a gate-assisted punchthrough mode. The cell structure, fabricated through the use of high energy ion implantation technology, enables both deep PD formation and transfer-gate (TG)/channel-stop (CS) length reduction. Deep PD formation helps increase sensitivity per PD unit area, and TG/CS length reduction widens both PD and V-CCD areas. Although the cell size is small (4.8 /spl mu/m (H)/spl times/5.6 /spl mu/m (V)), the sensor achieves both high sensitivity (35 mV/lx) and a high saturation signal (600 mV).<>     

Noise in semiconductor laser amplifiers with quantum box structure

The low-noise properties of a quantum-box traveling-wave semiconductor laser amplifier (QB-TW-SLA) are discussed. The gain and population-inversion parameter of a quantum-box structure are precisely expressed using density matrix theory. Due to sharp gain characteristics as well as a small population inversion parameter, dominant two-beat noise is significantly reduced, even in a solitary device without a narrow bandpass filter. The noise figure can be reduced to 3.5 dB     

Multicolor LCD for automotive applications

Segment-type, twisted nematic liquid-crystal panels with finely striped, two-color filters within the panel are discussed. The panel has a color filter-on-indium tin oxide structure. Two types of printed filter (an offset-printed (OP) filter and a screen-printed (SP) filter) were subjected to heat treatment and evaluated. It was found that an SP filter of about 0.3 μm has less effect on the operating voltage and availability for multiplexed drive than an OP filter of about 1 μm in thickness with the same color density. The test results for panel reliability for automotive use are given. The panels can digitally display a vehicle's speed, fuel level and engine revolutions in bargraph format with good legibility using three colors     

A 125-mm/sup 2/ 1-Gb NAND flash memory with 10-MByte/s program speed

A single 3-V only, 1-Gb NAND flash memory has been successfully developed. The chip has been fabricated using 0.13-/spl mu/m CMOS STI technology. The effective cell size including the select transistors is 0.077 /spl mu/m/sup 2/. To decrease the chip size, a new architecture is introduced. The in-series connected memory cells are increased from 16 to 32. Furthermore, as many as 16 k memory cells are connected to the same wordline. As a result, the chip size is decreased by 15%. A very small die size of 125 mm/sup 2/ and an excellent cell area efficiency of 70% are achieved. As for the performance, a very fast programming and serial read are realized. The highest program throughput ever of 10.6-MByte/s is realized: 1) by quadrupling the page size and 2) by newly introducing a write cache. In addition, the garbage collection is accelerated to 9.4-MByte/s. In addition, the write cache accelerates the serial read operation and a very fast 20-MByte/s read throughput is realized.     

Elimination of kink phenomena and drain current hysteresis in InP-based HEMTs with a direct ohmic structure

We eliminated kink phenomena and Ids hysteresis in a double-doped InP-based HEMT without degrading its frequency performance by fabricating direct ohmic contacts in the InGaAs channel. A direct ohmic structure lets us control current paths in the device and relax the electric field at the recess edge of the drain side. As a result, we can suppress impact ionization and decrease the hole currents that originate from the high electric field region at the recess edge of the drain side. Kink phenomena are eliminated in the direct ohmic structure. We also suggest a hole trap mechanism to explain the appearance of hysteresis in the I-V characteristic of the conventional nonalloyed ohmic structure device.     

Narrow linewidth characteristic of a 1.5 μm wavelengthsingle-mode phase-locked laser array

The linewidth of a 1.5-μm wavelength single-mode phase-locked laser array was measured. A relatively narrow linewidth of 203 kHz was obtained at an output power of 25 mW for a five-element phase-locked laser array that consists of a five-pair Ga_0.3In_0.7As/GaInAsP/InP compressively strained quantum-well active region and a mode controlling grating filter. This result indicates the reduced spontaneous emission factor due to a larger cavity size in the lateral direction     

Confirming Impurity Effect in Silver-Point Realization from Cell-to-Cell Comparisons

As a continuation to earlier work on the silver-point realization, already reported at TEMPMEKO 2007, a new silver-point cell has been fabricated using 6N-nominal grade material that was analyzed by means of glow discharge mass spectrometry (GDMS) by the manufacturer. This new cell is evaluated by a direct cell comparison with one of the existing cells, which was also already reported at TEMPMEKO 2007. One of those existing cells was drawn out from its crucible, and its ingot was analyzed by GDMS at four positions, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of middle areas for the purpose of confirming whether or not there has been differences in the content of impurities before and after the cell fabrication, as well as differences in impurity homogeneity within the ingot. As results of the aforementioned measurements, it was found that the homogeneity of impurities in the silver ingot was on average within 50 %. It was also found that cell-to-cell temperature differences change along with the progressing solidification process. As a consequence, it was concluded that, for an accurate cell-to-cell comparison, the location in the freezing plateau, where the comparison is done, should be determined. Also obtained here is that the slope analysis was consistent with both the cell-to-cell comparison and the impurity analysis.     

Environmental effects of physical life span of a reusable unit following functional and physical failures in a remanufacturing system

Reuse of product components is an effective way to conserve natural resources. Likewise, remanufacturing is a new trend in the field of environmentally friendly products. A product undergoes functional failure or physical failure in a remanufacturing environment, where the former failure is equivalent to the state in which the product cannot be used because of functional insufficiency or obsolescence and the latter failure is equivalent to the state of malfunction or breakdown of a product. A unit intended for reuse should be designed to be durable for a period equal to at least two functional lives through remanufacturing. Utilization of excess materials-for example, for improvement of unit strength-can enable a reusable unit to endure over a period equal to at least two functional lives. However, if the environmental impact of such excessive use of materials is taken into account, a strong doubt arises as to whether such a method truly reduces the environmental load from the viewpoint of lifecycle design. In order to analyse this issue, the present study examines the optimal physical life span of a reusable unit and its effect on the environment. A mathematical model of a remanufacturing system is constructed, taking into account functional and physical failures of a product. A minimization problem of the incurred total environmental impact per unit time for a reusable unit is formulated under the decision variables of a design parameter vector of the unit and the maximum number of times of reuse. The design parameter vector is closely related with physical life span. The maximum number of times of reuse can cause environmental loss if a product has a long residual physical life span brought on by the small number of times of reuse. The effects of physical life span of a reusable unit on environmental impact are analysed to show the potential value of the developed model by means of varying stochastic characteristics and the parameters of the remanufacturing environment.