Nanoscale two-bit/cell NAND silicon-oxide-nitride-oxide-silicon memory device with different tunneling oxide thicknesses.

Nanoscale two-bit/cell NAND-type silicon-oxide-nitride-oxide-silicon (SONOS) flash memory devices with different tunneling oxide thicknesses were designed to reduce the short channel effect and the coupling interference. The process step and the electrical characteristics of the proposed SONOS memory devices were simulated by using SUPREM-4 and MEDICI, respectively. The short channel effect in the nanoscale two-bit/cell SONOS devices was decreased than that of the conventional devices due to a larger effective channel length. The drain current at the on-state of the proposed NAND SONOS memory devices decreased than that of the conventional NAND SONOS devices due to the high channel resistivity. The I on/I off ratio of the proposed NAND SONOS memory devices was larger than that of the conventional memory devices due to the dramatic decrease in the subthreshold current of the proposed devices. The electrical characteristics of the NAND SONOS memory devices with different tunneling oxide thicknesses were better than those of the conventional NAND SONOS devices.

Nanoscale two-bit/cell NAND silicon-oxide-nitride-oxide-silicon devices with a separated double-gate saddle-type structure.

Nanoscale two-bit/cell NAND silicon-oxide-nitride-oxide-silicon flash memory devices based on a separated double-gate (SDG) saddle structure with a recess channel region had two different doping regions in silicon-fin channel to operate two-bit per cell. A simulation results showed that the short channel effect, the cross-talk problem between cells, and the increase in threshold voltage distribution were minimized, resulting in the enhancement of the scaling-down characteristics and the program/erase speed.

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

Stereoscopic image distortion in radial camera and projector configurations.

A closed-form solution of describing perceived image in stereoscopic imaging systems with radial recording and projecting geometry for arbitrary viewer positions is presented. This solution is derived by finding a condition for making the heights of homolog points in both left and right images projected on the screen in the geometry equal. The solution has the same equation form as that of the parallel geometry except that it has a constant shifting term in the horizontal direction. This term is a main source for distortions in the perceived image. The condition of eliminating the term makes the solution the same as that for stereoscopic imaging systems with parallel recording and projecting geometry.

Characteristics of pixel arrangements in various rhombuses for full-parallax three-dimensional image generation.

In full-parallax three-dimensional (3-D) imaging systems, the pixel cells often have the shape of a rhombus. Proper arrangement of pixels in these rhombic-shaped cells is important to maximize the quality of displayable 3-D images with a given display panel. The possible number of pixel arrangements in a rhombic cell with a definite dimension is found by considering the number of possible crossings between parallel line families forming the pixel cells, when the slopes of the lines are approximated by the ratio between the number of pixels in the vertical and horizontal directions. To make the rhombic cell have a uniquely defined pixel arrangement, its horizontal and vertical dimensions should be equal to the even multiple of the pixel dimension in their corresponding direction.