Floating-island TFT leakage caused by process step reduction

The leakage mechanism for a top-gate thin-film transistor (TFT) produced using the fewest process steps in the industry is analyzed in order to achieve a high-contrast liquid crystal display (LCD). Using a T-shaped TFT structure, the OFF and ON channel lengths are defined independently, so that the leakage can be reduced with no ON current decrease     

GaInAs-GaInNAs-GaInAs intermediate layer structure for longwavelength lasers

Proposes two new structures, the GaInAs-GaInNAs intermediate layer (IML) and the GaInN_xAs graded wells, which show better optical properties than the commonly used GaInNAs-GaAs rectangular quantum-wells. A 1240-nm emitting IML laser has been achieved with a low-threshold current density (200 A/cm²/well) and a relatively high characteristic temperature (T_o=100 K). The IML structure is very promising for long wavelength GaAs-based laser applications     

Room temperature continuous-wave operation of GaInNAs/GaAs VCSELsgrown by chemical beam epitaxy with output power exceeding 1 mW

The authors present a near 1200 nm wavelength vertical-cavity surface-emitting laser (VCSEL) the active region of which is formed by GaInNAs/GaAs quantum wells grown by chemical beam epitaxy. Room temperature continuous-wave operation has been demonstrated with a high slope efficiency of 0.23 W/A, a high output power of over 1.0 mW, and a singlemode output power of 0.34 mW. The fabricated devices with different aperture sizes show low threshold currents of 1.2-2.1 mA and a record low threshold current density of 2.6 kA/cm² in GaInNAs VCSELs     

An active integrated retrodirective transponder for remoteinformation retrieval-on-demand

A retrodirective transponder based on a novel compact phase-conjugating mixer with conversion gain has been developed. The active circuit uses one port for both incoming and outgoing signals, enabling a reduction of circuit size, and the balanced structure provides suppression of undesired signals. By using a modulated local oscillator, the circuit can modulate the received signal in order to retransmit local information to the remote site. A microstrip antenna is integrated with the phase conjugator and the whole system was fabricated on a single substrate, enabling a one-card system. A four-element prototype array with 0.5λ₀ array spacing demonstrated excellent measured retrodirectivity. Additionally, a simplified binary-phase-shift-keying signal transmitted by the array is recovered successfully at the source location, demonstrating great potential for remote tagging and wireless sensor applications     

Room temperature operation of GaInAs-GaInAsP-InP SCH multiquantum-film laser with narrow wire-like active region

GaInAs-GaInAsP-InP SCH (separate-confinement heterostructure) multiquantum-film lasers with approximately 100-nm-wide wirelike active regions were fabricated by two-step low-pressure organometallic vapor-phase epitaxy (LP-OMVPE) growth and wet chemical etching and operated at room temperature. An increase in the threshold current density in such lasers was drastically reduced by using a preheating process in hydrogen atmosphere and a thin InP cover layer growth prior to the regrowth of a GaInAsP optical confinement layer. The fabrication processes presented can be very effective for realization of room-temperature operation of long-wavelength quantum-wire and quantum-box lasers based on GaInAs-InP materials.<>     

Solar cell efficiency tables (Version 31)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July, 2008 are reviewed. Copyright © 2007 John Wiley & Sons, Ltd.     

1 Tbit/s (111 Gbit/s/ch X 10 ch) no-guard-interval CO-OFDM transmission over 2100 km DSF

Spectrally efficient (2bit/s/Hz) 1 Tbit/s DWDM transmission of 111 Gbit/s no-guard-interval PDM CO-OFDM signals with 50 GHz spacing over DSF is demonstrated. The record transmission distance of 2100 km was achieved for a 100 Gbit/s-data-rate CO-OFDM system.     

PMD compensation in optical coherent single carrier transmission using frequency-domain equalisation

The transmission performance of optical single-carrier (SC) transmission using frequency-domain equalisation (FDE) to counter polarisation mode dispersion (PMD) is evaluated. 25 Gbit/s coherent optical SC transmission using FDE (CO-SC-FDE) is demonstrated in the presence of a significant amount of differential group delay (DGD). The results show that CO-SC-FDE compensates for the influence of the 125 ps DGD; the OSNR penalty is 0.81 dB.     

Dual-Mode Space-Temporal Simultaneous Processing Equalizer

A tapped delayed line adaptive array antenna (TDL-AAA) and a space-temporal simultaneous processing equalizer (ST-SPE) are proposed as simple space-temporal equalizers based on minimum mean square error (MMSE) criterion. The ST-SPE has a compact hardware with a small number of taps compared to that of the TDL-AAA. The ST-SPE can reduce the computational complexity of the space-temporal joint equalization and it works effectively under the minimum phase condition such as appeared at line-of-sight (LOS) propagation environments at a high antenna height base station. However the ST-SPE cannot work under a non-minimum phase condition caused under N-LOS (non-line-of-sight). On the other hand, the TDL-AAA whose reference signal is synchronized at the center tap (TDL-AAA_C) can work even in the non-minimum phase condition. In this paper, we propose a dual-mode space-temporal simultaneous processing equalizer (Dual-mode ST-SPE) which has a simple configuration and also works in non-minimum phase condition. The Dual-mode ST-SPE can reduce the computational complexity compared to the TDL-AAA_C. Yoshihiro Ichikawa received the B.E. degree in department of communication engineering, in National Defense Academy in 1995, and M.E. and D.E. degree from Ibaraki University in 2001 and 2004, respectively. He joined the Japan Air Self Defense Force in 1995. His research interests are an adaptive algorithm, an antenna design, and an adaptive array antenna. Shigeki Obote received his B.E., M.E. and D.E. degrees in electrical and electronic engineering from Tottori University, Tottori, Japan, in 1996, 1998 and 2000, respectively. Since 2000, he has been with department of media and telecommunications engineering, faculty of engineering, Ibaraki University, Ibaraki, Japan, where he is currently a associate professor. His research interests are in adaptive array antenna and wireless communications systems. Kenichi Kagoshima received the B.E., M.E. and D.E. degrees in electronics engineering from the Tokyo Institute of Technology, Tokyo, Japan, in 1969, 1971, and 1974, respectively. He joined the Nippon Telegraph and Telephone Corporation (NTT) Laboratory in 1974 and researched and developed many kinds of radio communication antennas. Since 1997, he has been a professor at Ibaraki University, Ibaraki, Japan. Dr. Kagoshima was a Secretary and Treasure, Vice Chairman, and Chairman of the IEEE AP-S Tokyo Chapter in 1992, 1993, and 1994, respectively. He was a chair of antennas and propagation professional group of IEICE in 1999 and 2000. In 1973, he received the Yonezawa Prize for Young Engineers and 1998, best paper award from IEICE, respectively.     

Solar cell efficiency tables (version 43)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2013 are reviewed. Copyright © 2013 John Wiley & Sons, Ltd.