RESUMO
Graphene shows strong promise for the detection of terahertz (THz) radiation due to its high carrier mobility, compatibility with on-chip waveguides and transistors, and small heat capacitance. At the same time, weak reaction of graphene's physical properties on the detected radiation can be traced down to the absence of a band gap. Here, we study the effect of electrically induced band gap on THz detection in graphene bilayer with split-gate p-n junction. We show that gap induction leads to a simultaneous increase in current and voltage responsivities. At operating temperatures of â¼25 K, the responsivity at a 20 meV band gap is from 3 to 20 times larger than that in the gapless state. The maximum voltage responsivity of our devices at 0.13 THz illumination exceeds 50 kV/W, while the noise equivalent power falls down to 36 fW/Hz1/2.
RESUMO
Photoconductivity of novel materials is the key property of interest for design of photodetectors, optical modulators, and switches. Despite the photoconductivity of most novel 2d materials having been studied both theoretically and experimentally, the same is not true for 2d p-n junctions that are necessary blocks of most electronic devices. Here, we study the sub-terahertz photocoductivity of gapped bilayer graphene with electrically induced p-n junctions. We find a strong positive contribution from junctions to resistance, temperature resistance coefficient, and photoresistivity at cryogenic temperatures T â¼ 20 K. The contribution to these quantities from junctions exceeds strongly the bulk values at uniform channel doping even at small band gaps of â¼10 meV. We further show that positive junction photoresistance is a hallmark of interband tunneling, and not of intraband thermionic conduction. Our results point to the possibility of creating various interband tunneling devices based on bilayer graphene, including steep-switching transistors and selective sensors.
RESUMO
PURPOSE: An open-label, noninferiority study to evaluate the impact of epoetin alfa (EPO) on tumor outcomes when used to treat anemia in patients receiving chemotherapy for metastatic breast cancer. METHODS: Women with hemoglobin ≤ 11.0 g/dL, receiving first- or second-line chemotherapy for metastatic breast cancer, were randomly assigned to EPO 40,000 IU subcutaneously once a week or best standard of care. The primary end point was progression-free survival (PFS). Secondary end points included overall survival, time to tumor progression, overall response rate, RBC transfusions, and thrombotic vascular events. RESULTS: In 2,098 patients randomly assigned, median PFS (based on investigator-determined disease progression [PD]) was 7.4 months in both groups (hazard ratio [HR], 1.089; 95% CI, 0.988 to 1.200); upper bound exceeded prespecified noninferiority margin of 1.15. Median PFS per independent review committee-determined PD was 7.6 months in both groups (HR, 1.028; 95% CI, 0.922 to 1.146); upper bound did not exceed prespecified noninferiority margin. Median overall survival at clinical cutoff (1,337 deaths) was 17.2 months in the EPO and 17.4 months in the best standard of care group (HR, 1.057; 95% CI, 0.949 to 1.177), median time to tumor progression was 7.5 months in both groups (HR, 1.094; 95% CI, 0.991 to 1.209), and overall response rate was 50% versus 51% (odds ratio, 0.950; 95% CI, 0.799 to 1.130). RBC transfusions were 5.8% versus 11.4% (P < .001), and thrombotic vascular events were 2.8% versus 1.4% (P = .038), respectively. CONCLUSION: The primary end point, PFS based on investigator-determined PD, did not meet noninferiority criteria. As a consistency assessment with the primary finding, PFS based on independent review committee-determined PD met noninferiority criteria. Overall, this study did not achieve noninferiority objective in ruling out a 15% increased risk in PD/death. RBC transfusion should be the preferred approach for the management of anemia in this population.
