Shih-Fang Chen

A New Two-Dimensional Analytical Model for Nanoscale Symmetrical Tri-Material Gate Stack Double Gate Metal–Oxide–Semiconductor Field Effect Transistors

Based on the resultant solution of two-dimensional (2D) Poissons equation in silicon region, a new, compact and analytical model for nanoscale fully depleted, symmetrical tri-material gate stack double-gate (STMGSDG) metal–oxide–semiconductor field-effect transistor (MOSFET) has been developed. The STMGSDG MOSFET exhibits significantly reduced short-channel effects (SCEs) when compared with the symmetrical single-material gate stack double-gate (SSMGSDG) MOSFET. It is found that the threshold voltage roll-off for the fully depleted STMGSDG MOSFET can be effectively reduced by using both thin Si film and thin gate oxide. Besides, the high ratio of large work function of metal gate 1 (L1) to the total gate can efficiently suppress the drain-induced barrier lowering (DIBL) and maintain the low threshold voltage degradation. This study not only presents a precise 2D analytical model of the surface potential and threshold voltage, but also discusses the electric field distribution in the channel region, subthreshold swing and subthreshold current for the STMGSDG MOSFET. The new model is verified to be in a good agreement with numerical simulation results over a wide range of the device parameters.

Dramatic reduction of optical crosstalk in deep-submicrometer CMOS imager with air gap guard ring

A dielectric structure, air gap guard ring, has been successfully developed to reduce optical crosstalk thus improving pixel sensitivity of CMOS image sensor with 0.18-/spl mu/m technology. Based on refraction index (RI) differences between dielectric films (RI = 1.4 /spl sim/ 1.6) and air gap (RI = 1), total internal reflection occurred at dielectric-film/air-gap interface, thus the incident light is concentrated in selected pixel. Excellent optical performances have been demonstrated in 3.0 /spl times/ 3.0 /spl mu/m pixel. Optical spatial crosstalk achieves 80% reduction at 20/spl deg/ incidence angle and significantly alleviates the pixel sensitivity degradation with larger angle of incident light.

Color mixing improvement of CMOS image sensor with air-gap-guard ring in deep-submicrometer CMOS technology

In this letter, color mixings of a CMOS image sensor with air-gap-guard-ring (AGGR) and conventional structures were investigated in 0.18-/spl mu/m CMOS image sensor technology. As the light incident angle is increased from 0/spl deg/ to 15/spl deg/, conventional pixel shows serious color mixing. For example, the maximum photo responses of blue, green1, green2, and red pixels are shifted from 490 to 520 nm, 530 to 500 nm, 530 to 600 nm, and 600 to 580 nm, respectively. However, pixels with AGGR not only keep correct spectral response without peak shift but also achieve 5%-50% crosstalk reduction, thus preventing the sensor from color mixing efficiently.

A high-efficiency CMOS image sensor with air gap in situ MicroLens (AGML) fabricated by 0.18-/spl mu/m CMOS technology

The air gap in situ microlens (AGML) above-pixel sensor with 0.18-/spl mu/m CMOS image sensor technology has been successfully developed to dramatically improve the optical crosstalk and pixel sensitivity. We demonstrated excellent crosstalk diminution with the structure on small pixels. Compared with conventional 2.8 /spl mu/m square pixel, adopting the AGML can reduce the optical crosstalk up to 64%, and provide 21% in enhancement of photosensitivity at 0/spl deg/ incident angle. Furthermore, under 20/spl deg/ incident angle the optical crosstalk reduction and sensitivity enhancement are increased to 89% and 122%, respectively. Therefore, the AGML structure makes pixel size be further scaled down to less than 2.8 /spl mu/m square and maintain good performance.

Dramatic improving luminous efficiency of organic light emitting diodes under low driving current using nitrogen doped hole transporter

Abstract In this letter, output luminance, current efficiency and power efficiency of the organic light emitting diodes (OLEDs) with N 2 doped hole transport layer (HTL) have been studied in detail. Experimental results show that the current efficiency and the power efficiency thus in turn the output luminance of OLEDs prepared with HTL evaporated in the optimum N 2 gas ambient pressure of 1×10 −4 Torr are improved about 13, 9 and 12 times, respectively, under 2.7 mA/cm 2 driving current. The significant improving mechanism has been illustrated comprehensively with a series of schematic models.

Improving turn on voltage and driving voltage of organic electroluminescent devices with nitrogen doped electron transporter

Abstract In this letter, I/V curves, output luminance of the organic light emitting diodes (OLEDs) with N2 doped electron transport layer (ETL) have been studied in detail. Experimental results show that the turn on voltage and driving voltage of OLEDs with ETL evaporated in the optimum N2 gas ambient pressure of 1×10−4 Torr are reduced from 3.5 to 1 V and 7.7 to 5.7 V, respectively. The significant improving mechanism has been illustrated comprehensively with a schematic energy diagram model.

An effective method to improve the sensitivity of deep submicrometer CMOS image sensors

An effective method has been successfully developed to improve the sensitivity of deep sub-micrometer CMOS image sensors (CIS). In advanced CIS technology, the shallow trench isolation (STI) SiO/sub 2/ on the photodiode and the SiON film are used for silicide blocking and as a contact etching-stop layer, respectively. However, the dielectric structure, which is composed of an interlayer dielectric/SiON/STI/spl I.bar/SiO/sub 2//Si, causes a destructive interference and thus degrades quantum efficiency (QE), especially at short wavelengths. In this paper, an effective method for improving CIS sensitivity has been proposed, based on both theoretical analysis and simulation results, by removing the STI from the photodiode area and then forming a deposition of SiON. Experimental results show that a 40% QE improvement can be achieved under the irradiance of light at a wavelength of 450 nm.

The Effect of H-Treatment on Au-Induced Lateral Crystallization of Phosphorus-Doped a-Si : H Films

We report and model the use of preannealing hydrogen treatment to improve the growth length in Au-induced lateral crystallization (MILC) of phosphorous-doped a-Si:H. Doped phosphorus atoms generate a large number of dangling bonds, which then capture metal atoms and interrupt the MILC processing, thus retarding the growth length. With the hydrogen treatment, the dangling bonds are passivated, and thus the MILC-grown polysilicon length can be increased from 18.6 to 53.9 μm after 6 h annealing.

Significantly Enhancing Luminance of Organic Light-Emitting Diodes (OLEDs) with Doping Iodine and Nitrogen Treatment

Simultaneously doping iodine (I2) inorganic dopants and nitrogen (N2) treatment on hole transport layer (HTL) to promote the output luminance of the Al/ Tris-(8-hydroxyquinoline) aluminum (Alq3)/N, N’-diphenyl-N, N’bis (3-methylphenyl)-1, l’-bipheny-4, 4’-diamine (TPD)/ITO organic light-emitting diodes (OLEDs) has been studied in detail. Experimental results show that the output luminance can be significantly promoted up to 950% and 560% in magnitude at bias of 8V and 10V, respectively. We attribute the obvious promotion to significant morphological changes occurring in HTL as a result of the di-nitrogen occlusion and I2 dopant generated guest hopping sites. The morphological changes improve the HTL/Alq3 interface while the interfering action between guest and host hopping sites lowers hole mobility thus raising the output luminance in the OLEDs.

Improving Boron-Induced Retardation of Metal-Induced Lateral Crystallization Length by Hydrogen Treatment

In this letter, we use hydrogen treatment to improve boron-dopant-induced growth length retardation in metal-induced lateral crystallization (MILC) of amorphous silicon film (a-Si). Compared with the case without hydrogen treatment, a scanning electron microscope (SEM) micrograph shows that the grown poly-silicon length in boron-doped a-Si film can be increased from 7 to 40 mm after 6 h of MILC annealing. The doped boron atoms generate a large number of dangling bonds, which then capture the metal atoms to interrupt the MILC processing thus retarding the growth length. Therefore, the obvious enhancement in MILC length is attributed to the passivation of dangling bonds with hydrogen atoms. [DOI: 10.1143/JJAP.44.L1039]