-
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate, for the first time, a unique p-i-n diode structure composed of ensembles of unintentionally doped InP nanowires bridging p-type and n-type hydrogenated microcrystalline silicon (muc-Si:H) layers on a quartz substrate. Selective area growth was used to restrict nanowires to the perimeter of a circular hole etched into vertically stacked p+ muc-Si:H/SiO<sub>2</sub>/n+ muc-Si:H thin films. DC electrical measurements confirm diode current-voltage characteristics with 25 nA reverse leakage current and an ideality factor of 3.9. Our demonstration suggests that active devices incorporating III-V compound semiconductor nanowires can be integrated onto low cost non- single crystal material platforms.
Nanotechnology, 2008. NANO '08. 8th IEEE Conference on; 09/2008
-
V.J. Logeeswaran,
A. Sarkar,
M.S. Islam, N.P. Kobayashi,
J. Straznicky,
Xuema Li,
Wei Wu,
Sagi Mathai,
M.R.T. Tan,
Shih-Yuan Wang,
R.S. Williams
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate a high-speed polarization-insensitive photoconductor based on intersecting InP nanowires synthesized between
a pair of hydrogenated silicon electrodes deposited on amorphous SiO2 surfaces prepared on silicon substrates. A 14-ps full width at half maximum de-embedded impulse response is measured, which
is the fastest reported response for a photodetector fabricated using nanowires. The high-speed electrical signal measurements
from the photoconductor are performed by an integrated coplanar waveguide transmission line. The demonstrated ability to grow
intersecting InP nanowires on hydrogenated microcrystalline Si surfaces will facilitate the construction of ultra-fast photodetectors
on a wide range of substrates.
Applied Physics A 03/2008; 91(1):1-5. · 1.63 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We describe the fabrication and characterization of photoconductors in which an ensemble of indium phosphide nanoneedles was utilized. DC electrical transport properties of the fabricated photoconductors were characterized under illumination with monochromatic light at 633 nm. This is the first demonstration of III-V compound semiconductor nanometerscale structures monolithically integrated on non-single crystalline silicon-based materials as an optoelectronic device that can be fabricated by a simple and flexible process not limited by single crystal substrates.
Nanotechnology, 2007. IEEE-NANO 2007. 7th IEEE Conference on; 09/2007
-
[show abstract]
[hide abstract]
ABSTRACT: The epitaxial growth of nanometer-scale structures on non-single crystalline surfaces is proposed and demonstrated. Hydrogenated amorphous silicon was deposited onto an SiO2 surface by plasma-enhanced chemical vapor deposition. Indium phosphide was deposited on the amorphous silicon by low-pressure metalorganic chemical vapor deposition in the presence of colloidal gold particles as catalysts. Under specific growth conditions, the indium phosphide formed nanoneedles connected to a microcrystalline silicon film nucleated within the amorphous silicon during the growth of the nanoneedles. Transmission electron microscopy revealed the presence of two different crystallographic structures: zinc-blende and wurtzite. Micro-photoluminescence measurements at room temperature showed two peaks with substantial blue-shifts with respect to that of bulk zinc-blende indium phosphide.
Applied Physics A 09/2006; 85(1):1-6. · 1.63 Impact Factor
-
R.G. Broeke,
J. Cao,
C. Ji,
Y. Du,
N. Chubun,
P. Bjeletich,
S.J.B. Yoo,
R. Welty,
P.L. Stephan,
C. Reinhardt,
I.Y. Han, N.P. Kobayashi
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate a monolithically integrated InP optical-CDMA encoder/decoder chip encoding sub-picosecond pulses in the 1.55 μm wavelength window using eight orthogonal Walsh codes. The chip consists of two 200 GHz AWGs and electro-optic phase modulators in InP/InGaAsP.
Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE; 12/2004
-
[show abstract]
[hide abstract]
ABSTRACT: InGaN/GaN quantum wells (QW) were grown by metalorganic chemical vapor deposition (MOCVD) on pyramids of epitaxial lateral
overgrown (ELO) GaN samples. The ELO GaN samples were grown by MOCVD on sapphire (0001) substrates that were patterned with
a SiNx mask. Scanning electron microscopy and cathodoluminescence (CL) imaging experiments were performed to examine lateral variations
in structure and QW luminescence energy. CL wavelength imaging (CLWI) measurements show that the QW peaks on the top of the
grooves are red-shifted in comparison with the QW emission from the side walls. The results show that In atoms have migrated
to the top of the pyramids during the QW growth. The effects of V/III ratio, growth temperature as well as ELO GaN stripe
orientation on the QW properties are also studied.
Journal of Electronic Materials 12/1999; 29(1):10-14. · 1.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Summary form only given. We will describe the application of stable AlGaAs oxides as integrable low index optical materials and insulators in VCSEL based OEICs where the oxide serves not only as a current and mode aperture in but as an optical material that can be used to engineer the reflectivity of VCSEL mirrors and the cavity refractive index profile
Lasers and Electro-Optics Society Annual Meeting, 1998. LEOS '98. IEEE; 01/1999
-
Applied Physics Letters 01/1999; 74(19):2836-2838. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Spatially, spectrally, and temporally resolved cathodoluminescence (CL) techniques have been employed to examine the optical properties and kinetics of carrier relaxation for metalorganic chemical vapor deposition grown InGaN/GaN single quantum wells (QWs). Cathodoluminescence wavelength imaging of the QW sample revealed local band gap variations, indicating the presence of local In composition fluctuations and segregation during growth. A detailed time-resolved CL study shows that carriers generated in the boundary regions will diffuse toward and recombine at InN-rich centers, resulting in a strong lateral excitonic localization prior to radiative recombination. © 1998 American Institute of Physics.
Applied Physics Letters 09/1998; 73(10):1430-1432. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Defect formation and In segregation in InGaN/GaN quantum wells grown at various temperatures and with various well thicknesses were studied using cathodoluminescence, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). In0.16Ga0.84N quantum wells with In compositional nonuniformity and a small number of structural defects originating at the InGaN/GaN interface showed sharp and intense InGaN emission in cathodoluminescence (CL). Increasing the In composition caused surface roughness in the InGaN layer and the formation of stacking faults/dislocations originating at InGaN/GaN interface. This resulted in a reduction of the InGaN emission peak intensity.
Journal of Crystal Growth 02/1998; 195:252-257. · 1.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Defect formation and In segregation in InGaN/GaN quantum wells grown at various temperatures and with various well thicknesses were studied using cathodoluminescence, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). In Ga N quantum wells with In compositional nonuniformity and a small number of structural defects originating at the InGaN/GaN interface showed sharp and intense InGaN emission in cathodoluminescence (CL). Increasing the In composition caused surface roughness in the InGaN layer and the formation of stacking faults/dislocations originating at InGaN/GaN interface. This resulted in a reduction of the InGaN emission peak intensity. 1998 Elsevier Science B.V. All rights reserved.
Journal of Crystal Growth55.Nq66.Fd. 01/1998; 1956015(81).
-
Journal of Crystal Growth 01/1998; 189:172-177. · 1.73 Impact Factor
-
Journal of Crystal Growth 01/1998; 189:172-177. · 1.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have demonstrated that GaN can be grown epitaxially by atmospheric pressure metalorganic chemical vapor deposition on an aluminum oxide compound layer utilized as an intermediate layer between GaN and a Si(111). X-ray diffraction measurement indicates that single-crystal hexagonal GaN with its basal plane parallel to the Si(111) plane is grown. Using a scanning electron microscope, the macroscopic evolution of GaN grown on the AlOx/Si(111) substrate is found to be similar to that of GaN grown on a sapphire(0001) substrate. Cathodoluminescence (CL) spectrum shows a unique emission that consists of several peaks with the intensity comparable to that of the near-band-edge emission. Unique characteristics in CL spectrum are discussed in terms of a possible oxygen contamination of GaN grown on the AlOx/Si(111) substrate. © 1997 American Institute of Physics.
Applied Physics Letters 12/1997; 71(24):3569-3571. · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Summary form only given. In this talk, we will discuss dependance of this growth mode on various reactor parameters including reactant flows, carrier gas, rotation speed and separation between the showerhead and substrate. These parameters all effect the hydrodynamics and chemical reaction pathways of this unique reactor design. We will discuss how the growth conditions affect the formation of the three dimensional islands and now the variation in the density and the size or the islands at the initial stages of overlayer growth affect the coalescence of the islands and the surface morphology and electrical, structural and optical quality of the GaN overlayer
Vertical-Cavity Lasers, Technologies for a Global Information Infrastructure, WDM Components Technology, Advanced Semiconductor Lasers and Applications, Gallium Nitride Materials, Processing, and Devi; 09/1997
-
[show abstract]
[hide abstract]
ABSTRACT: Formation and coalescence of GaN truncated three dimensional islands (TTIs) on (0001) sapphire are observed during growth
of GaN using a close spaced metalorganic chemical vapor deposition reactor. To encourage formation of TTIs to occur uniformly
over the buffer layer, growth conditions are chosen under which thermal desorption and/or mass transport of the buffer layer
can be suppressed. During coalescence of TTIs, growth conditions that favor higher desorption of species on the GaN (0001)
surface and incorporation on other planes are beneficial. Therefore, changing the growth conditions as the growth mode changes
is effective to obtain both good crystallinity and flat surface morphology.
Journal of Electronic Materials 01/1997; 26(10):1114-1117. · 1.47 Impact Factor
