김성미 교수

We report results of small-signal modulation characteristics of self-assembled 1.3-μm InGaAs-GaAs quantum dot (QD) lasers at room temperature. The narrow ridge-waveguide lasers were fabricated with multistack InGaAs self-assembled QDs in active region. A high characteristic temperature of T/sub o/=210 K with threshold current density of 200A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was obtained. Small-signal modulation bandwidth of

High-efficiency optical emission past 1.3 /spl mu/m of GaInNAs on GaAs, with an ultimate goal of a high-power 1.55-/spl mu/m vertical-cavity surface-emitting laser (VCSEL), has proven to be elusive. While GaInNAs could theoretically be grown lattice-matched to GaAs with a very small bandgap, wavelengths are actually limited by the N solubility limit and the high In strain limit. By adding Sb to the GaInNAs quaternary, we have observed a remarkable shift toward longer luminescent wavelengths whil

We report two-color InGaAs quantum-dot infrared photodetectors. The InGaAs self-assembled quantum dots were grown on InGaP matrix via metal-organic chemical vapor deposition and fabricated as intersubband photoconductive structure. Bias-controlled two-color photoconductive responses were obtained at two different infrared window, mid-infrared of /spl lambda/=5.5 μm and far-infrared of /spl lambda/=9.2 μm at 77 K. Our devices were operated with low dark currents and high optical gains, and result

This study demonstrates multi-spectral operation of InGaAs quantum dot infrared photodetectors that display peak responsivity and peak detectivity at 77 K. The applications of multi-spectral infrared sensors are also discussed in detail.

OBJECTIVE: Universal suicide risk screening in pediatric primary care settings is lacking, despite the endorsement of this practice by several national organizations. This study explores barriers to and facilitators of implementing universal suicide risk screening in pediatric primary care clinics, with a focus on clinics that had not yet adopted this practice. METHODS: We conducted a qualitative study consisting of semistructured interviews with primary care clinicians and support staff involve

We report the growth and characterization of a new dilute nitride, InNSb quantum dots embedded on both InAs and GaAs substrate. Strain induced, self-assembled quantum dots are grown using solid-source molecular beam epitaxy. For improved growth control, we developed a growth technique similar to atomic layer epitaxial methods. Nitrogen incorporation during formation of quantum dots changes surface energy barrier and causes anisotropic distribution of strain energy, results in formation of closel

Vertical device architectures are attracting attention for power electronics applications owing to their high current capabilities and space-efficient layouts. In this study, we demonstrate a GaN-based vertical heterojunction bipolar transistor employing aluminum-doped zinc oxide (AZO) as the collector layer, deposited by radio frequency sputtering at a low temperature. This low-temperature process avoids thermal damage to the underlying p-GaN base layer and provides a fabrication-compatible rou

The use of the Stanford Mark III electron accelerator presents special difficulties for channeling experiments due to its low-duty factor pulses. To compensate for the low-duty cycle of the channeled electron beam, the author utilized the high average current generated by the accelerator and analyzed the X-ray output using a turnable X-ray monochromator and a semiconductor detector operating in the current mode, rather than in the normal pulse mode. Cooling of the specimen was achieved by using

The theoretical literature on heterogeneous firms and trade explains how differences in productivity determine which firms enter export markets. Yet even among exporters, productivity varies considerably: some firms export multiple products to numerous destinations, while others export a single product to only one market. This paper focuses on the latter group – marginal or low-intensity exporters – offering a descriptive analysis to better understand how productivity shapes export behavior beyo

In this paper characteristics of long wavelength quantum dots lasers is discussed. Small signal modulation response was measured at room temperature under CW biasing condition with a network analyzer (HP8510), a high speed InGaAs photodetector, and a low-noise amplifier.

The K-DHLI is a reliable and valid instrument for assessing DHL in the Korean population. The findings confirm that the 7-factor structure demonstrates superior model fit and further support its applicability across diverse adult groups. This study provides a standardized instrument for assessing DHL in Korea and facilitates its use in national surveys, clinical screening, and research. It may help identify individuals with limited DHL, thereby supporting targeted interventions to reduce health