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1.
Thanks to rapid progress in microelectronics technology, a new, nomadic lifestyle has become widespread these days. People, regardless of location, enjoy greater connectivity through communication networks and intelligent electronic terminals. This nomadic lifestyle will become even more common as technology frees people from the constraints of time and location. The cool chip, characterized by high performance and low power consumption, will play a key role in inaugurating the Nomadic Age. Rather than describe its technical details, we take a broader, more historic view of the cool chip's impact. More than a necessary innovation, cool chips' increased portability and reduced power consumption will play a key role in building a better future society 相似文献
2.
High spectral efficiency combined with power efficiency, is a requirement for high speed digital broadcast satellite systems. The effect of the recovered carrier phase noise and the nonlinearity on the performance of 16-QAM (quadrature amplitude modulation) and staggered 16-QAM is investigated and compared. It is found that for the phase noise, 16-QAM is more degraded for a roll-off factor of less than 0.4. For roll-off factor of more than 0.8, staggered 16-QAM has superior performance. For the nonlinearity staggered 16-QAM is more sensitive for a roll-off factor of less than 0.4. It is concluded that coincident 16-QAM is suitable for spectrally efficient digital broadcast systems 相似文献
3.
C. X. Wang N. Maeda M. Hiroki T. Tawara T. Makimoto T. Kobayahsi T. Enoki 《Journal of Electronic Materials》2005,34(4):361-364
AlGaN/GaN-based metal-insulator-semiconductor heterostructure field-effect transistors (MIS-HFETs) with Al2O3/Si3N4 bilayer as insulator have been investigated in detail, and compared with the conventional HFET and Si3N4-based MIS-HFET devices. Al2O3/Si3N4 bilayer-based MIS-HFETs exhibited much lower gate current leakage than conventional HFET and Si3N4-based MIS devices under reverse gate bias, and leakage as low as 1×10−11 A/mm at −15 V has been achieved in Al2O3/Si3N4-based MIS devices. By using ultrathin Al2O3/Si3N4 bilayer, very high maximum transconductance of more than 180 mS/mm with ultra-low gate leakage has been obtained in the MIS-HFET
device with gate length of 1.5 μm, a reduction less than 5% in maximum transconductance compared with the conventional HFET
device. This value was much smaller than the more than 30% reduction in the Si3N4-based MIS device, due to the employment of ultra-thin bilayer with large dielectric constant and the large conduction band
offset between Al2O3 and nitrides. This work demonstrates that Al2O3/Si3N4 bilayer insulator is a superior candidate for nitrides-based MIS-HFET devices. 相似文献
4.
K. Ueda M. Kasu Y. Yamauchi T. Makimoto M. Schwitters D.J. Twitchen G.A. Scarsbrook S.E. Coe 《Diamond and Related Materials》2006,15(11-12):1954
We characterized high-quality polycrystalline diamond with large grains and fabricated polycrystalline diamond field effect transistors (FETs). The polycrystalline diamond had (110) preferred orientation, and its typical grain size was 100 μm. Well-resolved free exciton related emissions were observed at room temperature in cathodoluminescence. The FETs showed extremely high DC and RF performance. The cut-off frequency for current gain (fT) and power gain (fmax) were 45 and 120 GHz, respectively. The maximum drain current (IDS) was 550 mA/mm. These values are the highest among diamond FETs, including those fabricated from single-crystal diamond. These results suggest that high-quality polycrystalline diamond, whose maximum size is 4 in., is very promising for diamond electronic devices. 相似文献
5.
High-pressure and high-temperature (HPHT) annealing effects on the chemical vapor-deposited (CVD) homoepitaxial diamond films were investigated. By the HPHT annealing, the intensity of free-exciton (FE)-related emission was increased by 2 times and the luminescence bands from 270 to 320 nm, which originate from 5RL and 2BD bands, were almost completely eliminated in the cathodoluminescence (CL) spectrum. The CL intensity of band-A emission, which is related to crystal defects in diamond, was also decreased. The hole mobility at room temperature was increased from 826 to 1030 cm2/Vs by HPHT annealing. These results suggest that HPHT annealing decreases the crystalline defects and improves the optical and electronic properties of homoepitaxial diamond films. 相似文献
6.
Y Kawano Y Takaue P Law T Watanabe T Abe Y Okamoto A Makimoto J Sato R Nakagawa T Kajiume A Hirao A Watanabe Y Kuroda 《Canadian Metallurgical Quarterly》1998,22(10):1011-1017
The quality of population-based cancer registries has been measured by the indices of the proportion of total incident cases (DCO%) registered by death certificate only (DCO), and the ratio of incidence to mortality (I/D ratio). Recently it has been recommended that DCO% should be used as an index for the reliability of diagnosing cancers and that the proportion of cases first notified via death certificate (DCN, DCN%) be used as an index for the completeness of registration. Parkin introduced a method to estimate the registration rate, the estimated proportion of the "true incidence" that are registered in population-based registries. We recommend a modified method for estimating the registration rate for cancer registries where DCN% is relatively high, as it is in Japan, as Parkin's method may overestimate the registration rate. The method is as follows: the registration rate = (1-DCN% x 1/D ratio)/(1-DCN%). The registration rates at the Osaka Cancer Registry between 1966 and 1992 were estimated using our method. During this period, the yearly registration rate was 74.6-78.4% for males and 69.1-73.3% for females. When the cancer cases were looked at according to site, the yearly registration rate was 74.2-81.6% for stomach cancer, 81.2-89.3% for lung cancer, and 71.3-76.9% for uterine cancer. These results show that the registration rate is high for cancers that have an unfavorable prognosis and low for cancers that have a favorable prognosis. We recommend that all cancer registries in Japan calculate the completeness of registration by utilizing DCN defined as the sum of DCO plus cases not reported as cancer but with supportive clinical information of such obtained through survey of the registry for DCN. 相似文献
7.
Jin-Yu Shiu Jui-Chien Huang Desmaris V. Chia-Ta Chang Chung-Yu Lu Kumakura K. Makimoto T. Zirath H. Rorsman N. Chang E.Y. 《Electron Device Letters, IEEE》2007,28(6):476-478
A multienergy oxygen ion implantation process was demonstrated to be compatible with the processing of high- power microwave AlGaN/GaN high electron mobility transistors (HEMTs). HEMTs that are isolated by this process exhibited gate-lag- and drain-lag-free operation. A maximum output power density of 5.3 W/mm at Vgs = -4 V and Vds = 50 V and a maximum power added efficiency of 51.5% at Vgs = -4 V and Vds = 30 V at 3 GHz were demonstrated on HEMTs without field plates on sapphire substrate. This isolation process results in planar HEMTs, circumventing potential problems with enhanced gate leakage due to the gate contacting the 2-D electron gas at the mesa sidewall. 相似文献
8.
T Takasaki K Sugita N Fujii M Higashikawa K Makimoto H Takahashi Y Ohinata Y Fujiwara S Motoyama J Yamaguchi 《Canadian Metallurgical Quarterly》1993,67(5):440-443
Human herpesvirus-6 (HHV-6) is the causative agent for exanthem subitum. This study investigated the relationship between idiopathic facial nerve palsy (Bell's palsy), sudden deafness and HHV-6 infection. Both Bell's palsy and sudden deafness are syndromes which causes are unknown. Both of them are suspected viral infection as causative agents. Paired sera from 22 patients of Bell's palsy and 39 patients of sudden deafness were examined for reactivity to HHV-6 by the indirect immunofluorescence test. On a case of Bell's palsy and two cases of sudden deafness each of the HHV-6 antibody titers was increased. 相似文献
9.
Three types of growth defects commonly found epitaxial diamond films grown by chemical vapour deposition (CVD), namely unepitaxial crystals (UCs), hillocks with flat top (FHs) and pyramidal hillocks (PHs), were etched using hydrogen/oxygen plasma to discuss their origin. UCs formed at random locations on the grown layer without any apparent relation with the substrate. Their nucleation might be due to contaminants and their development controlled by the growth conditions in the plasma. In contrast, dislocations formed from impurities segregated at the interface between the substrate and the CVD layer, were found to be the origin of the FHs and the PHs. A simple crystal model that involves micro-faceting or twinning at an intrinsic stacking fault originating from the dislocation core is proposed to explain the formation and the evolution of the growth defects. 相似文献
10.
Ueda K. Kasu M. Yamauchi Y. Makimoto T. Schwitters M. Twitchen D.J. Scarsbrook G.A. Coe S.E. 《Electron Device Letters, IEEE》2006,27(7):570-572
Using high-quality polycrystalline chemical-vapor-deposited diamond films with large grains (/spl sim/100 /spl mu/m), field effect transistors (FETs) with gate lengths of 0.1 /spl mu/m were fabricated. From the RF characteristics, the maximum transition frequency f/sub T/ and the maximum frequency of oscillation f/sub max/ were /spl sim/ 45 and /spl sim/ 120 GHz, respectively. The f/sub T/ and f/sub max/ values are much higher than the highest values for single-crystalline diamond FETs. The dc characteristics of the FET showed a drain-current density I/sub DS/ of 550 mA/mm at gate-source voltage V/sub GS/ of -3.5 V and a maximum transconductance g/sub m/ of 143 mS/mm at drain voltage V/sub DS/ of -8 V. These results indicate that the high-quality polycrystalline diamond film, whose maximum size is 4 in at present, is a most promising substrate for diamond electronic devices. 相似文献