Masaharu Nagai

ZnCdSe/ZnSSe/ZnMgSSe SCH Laser Diode with a GaAs Buffer Layer

Blue-green laser diodes exhibiting continuous-wave operation during hundreds-of-seconds have been fabricated. This structure is a ZnCdSe/ZnSSe/ZnMgSSe separate-confinement heterostructure with low dislocation density of ~105 cm-2 in the n-ZnMgSSe cladding layer. The use of a GaAs buffer layer has lead to the decrease of dislocation density for laser-diodes, with which we have observed CW operation up to 80° C, that showed the feasibility of ZnCdSe/ZnSSe/ZnMgSSe SCH laser-diodes.

Electrical characteristics and short-channel effect of c-axis aligned crystal indium gallium zinc oxide transistor with short channel length

A channel length of a c-axis aligned crystal indium gallium zinc oxide (CAAC-IGZO) transistor having low off-state current at a yA/?m level was decreased to 100 nm, and the electrical characteristics and short-channel effect of the CAAC-IGZO transistor were researched. As a result, we found that, in the CAAC-IGZO transistor with L = 100 nm, even with a gate insulator film having an equivalent oxide thickness (EOT) = 11 nm, an extremely small off-state current of 380 yA/?m at 85 ?C is maintained, in addition channel length dependence of the electrical characteristics is hardly seen. Favorable values of characteristics of the CAAC-IGZO transistor can be obtained, such as subthreshold slope (SS) = 77 mV/dec, drain induced barrier lowering (DIBL) = 73 mV/V, threshold voltage (Vth) = 0.65 V, and on-state current (Ion) = 65 ?A/?m. These results suggest the possibility that the CAAC-IGZO transistor can be applied to an LSI in a deep submicron region.

Fabrication of dynamic oxide semiconductor random access memory with 3.9 fF storage capacitance and greater than 1 h retention by using c-axis aligned crystalline oxide semiconductor transistor with L of 60 nm

A dynamic oxide semiconductor random access memory (DOSRAM) array that achieves reduction in storage capacitance (Cs) and decrease in refresh rate has been fabricated by using a c-axis aligned crystalline oxide semiconductor (CAAC-OS) transistor (L = 60 nm) with an extremely low off-state current. We have confirmed that this array, composed of cells that include a CAAC-OS transistor with W/L = 40 nm/60 nm using InGaZnO and a 3.9 fF storage capacitor, operates with write and read times of 5 ns. Therefore, DOSRAM can ensure sufficient Cs while maintaining operation speed comparable to that of dynamic random access memory (DRAM). We have found that the read signal voltage of DOSRAM is changed by approximately 30 mV after 1 h at 85 °C. Thus, DOSRAM is a promising replacement for DRAM.

Effect of Surrounded-Channel Structure on Electrical Characteristics of

In this letter, we report the electrical characteristics of a crystalline oxide semiconductor, especially c-axis aligned crystalline In-Ga-Zn-O (CAAC-IGZO) field-effect transistors (FETs) having a surrounded-channel structure with 51-nm channel lengths, 11-nm equivalent oxide thicknesses of the gate insulating films, and various channel widths. The results show that the influence of the gate electrode on the sides of the channel increases as the channel width is reduced, which leads to excellent OFF-state and ON-state current characteristics of the FET with a 51-nm channel length and a 50-nm channel width. By exploiting these characteristics, low-power large-scale integration (LSI) applications become possible that would not be possible with conventional Si-LSI techniques.

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Transistors with Extremely Low Off-State Current Yoshiyuki Kobayashi, Shinpei Matsuda, Daisuke Matsubayashi, Hideomi Suzawa, Masayuki Sakakura, Kazuya Hanaoka, Yutaka Okazaki, Tsutomu Yamamoto, Suguru Hondo, Takashi Hamada, Shinya Sasagawa, Masaharu Nagai, Yuki Hata, Tetsunori Maruyama, Yoshitaka Yamamoto, and Shunpei Yamazaki Semiconductor Energy Laboratory Co., Ltd., 398 Hase, Atsugi, Kanagawa, 243-0036, Japan Phone: +81-46-248-1131 Fax: +81-46-270-3751, E-mail: yk1276@sel.co.jp

-Axis Aligned Crystalline In–Ga–Zn–O Field-Effect Transistor

Nitrogen doping in ZnSe using a new type of electron-cyclotron-resonance (ECR) source has been investigated. Selective nitrogen radical doping is performed using the ECR source with an external electrode, which can remove charged particles in the nitrogen plasma by the electrode applied electric field. Nitrogen ions are trapped by the electrode and the ion current is measured as a function of the electric field. The activation ratio of nitrogen atoms is investigated for various doping conditions by comparing the carrier profile and the atomic nitrogen profile, which are measured by capacitance–voltage techniques and secondary ion mass spectrometry. It was confirmed that nitrogen ions are removed and do not play a role as p-type dopants in ZnSe growth by molecular beam epitaxy. The activation ratio of nitrogen atoms is increased by removing the nitrogen ions.