43 research outputs found
Generation of 1180 Å period gratings with a Xe ion laser
Holographic lithography with the 2315 Å line of a xenon ion laser is used to produce gratings in polymethylmethacrylate. An 1180 Å period grating is made and examined with a scanning electron microscope (SEM). This grating period is appropriate for use as a first-order grating with a GaAs distributed feedback laser
A novel technique for the direct determination of carrier diffusion lengths in GaAs/AlGaAs heterostructures using cathodoluminescence
A new technique for determining carrier diffusion lengths
in direct gap semiconductors by cathodoluminescence measurement
is presented. Ambipolar diffusion lengths are
determined for GaAs quantum well material, bulk GaAs,
and Al_xGa_(1-x)As with x up to 0.38. A large increase in
the diffusion length is found as x approaches 0.38 and is
attributed to an order of magnitude increase in lifetime
Direct determination of the ambipolar diffusion length in GaAs/AlGaAs heterostructures by cathodoluminescence
A new technique for determining carrier diffusion lengths by cathodoluminescence measurements is presented. The technique is extremely accurate and can be applied to a variety of structures. Ambipolar diffusion lengths are determined for GaAs quantum well material, bulk GaAs, Al0.21Ga0.79As, and Al0.37Ga0.63As. A large increase in the diffusion length is found for Al0.37Ga0.63As and is attributed to an order of magnitude increase in lifetime
Effect of Al mole fraction on carrier diffusion lengths and lifetimes in AlxGa1−xAs
The ambipolar diffusion length and carrier lifetime are measured in AlxGa1−xAs for several mole fractions in the interval 0<x<0.38. These parameters are found to have significantly higher values in the higher mole fraction samples. These increases are attributed to occupation of states in the indirect valleys, and supporting calculations are presented
Argon I lines produced in a hollow cathode source, 332 nm to 5865 nm
We report precision measurements by
Fourier transform spectroscopy of the
vacuum wavenumber, line width, and relative
signal strength of 928 lines in the
Ar I spectrum. Wavelength in air and classification
of the transition are supplied for
each line. A comparison of our results with
other precision measurements illustrates
the sensitivity of Ar I wavelengths to conditions
in the light source
Argon I lines produced in a hollow cathode source, 332 nm to 5865 nm
We report precision measurements by
Fourier transform spectroscopy of the
vacuum wavenumber, line width, and relative
signal strength of 928 lines in the
Ar I spectrum. Wavelength in air and classification
of the transition are supplied for
each line. A comparison of our results with
other precision measurements illustrates
the sensitivity of Ar I wavelengths to conditions
in the light source
Direct determination of the ambipolar diffusion length in GaAs/AlGaAs heterostructures by cathodoluminescence
Application of selective epitaxy to fabrication of nanometer scale wire and dot structures
Probing quantum confinement within single core-multishell nanowires
Theoretically core-multishell nanowires under a cross-section of hexagonal geometry should exhibit peculiar confinement effects. Using a hard X-ray nanobeam, here we show experimental evidence for carrier localization phenomena at the hexagon corners by combining synchrotron excited optical luminescence with simultaneous X-ray fluorescence spectroscopy. Applied to single coaxial n-GaN/InGaN multiquantum-well/p-GaN nanowires, our experiment narrows the gap between optical microscopy and high-resolution X-ray imaging and calls for further studies on the underlying mechanisms of optoelectronic nanodevices. © 2012 American Chemical Society.The authors thank Irina Snigireva and Armando Vicente Sole for their assistance with the SEM measurements and data processing using PyMca, respectively. We thank Remi Tocoulou and Peter Cloetens for their help and the ESRF for the beam time allocated. We also thank Andrei Rogalev for the valuable discussions and Gary Admans for the critical reading of the manuscript. This work has been partially supported by the NANOWIRING Marie Curie ITN (EU project no. PITN-GA-2010-265073), as well as by the EPIC-NANOTICS (TEC2011-29120-C05-04) and Q&C-LIGHT (S2009ESP-1503) from Spanish MEC and CAM, respectively.Martínez Criado, G.; Homs Puron, AA.; Alen, B.; Sans Tresserras, JÁ.; Segura Ruiz, J.; Molina Sánchez, A.; Susini, J.... (2012). Probing quantum confinement within single core-multishell nanowires. Nano Letters. 12(11):5829-5834. https://doi.org/10.1021/nl303178uS58295834121