Selective Metalorganic Chemical Vapor Deposition Research Articles

Analysis and optimization of the edge effect for III–V nanowire synthesis via selective area metal-organic chemical vapor deposition

Selective Area Metal-Organic Chemical Vapor Deposition (SA-MOCVD) is a promising technique for the scale-up of nanowire fabrication. Our previous study investigated the growth mechanism of SA-MOCVD processes by quantifying contributions from various diffusion sources. However, the edge effect on nanostructure uniformity captured by skirt area diffusion was not quantitatively analyzed. This work further improves our understanding of the process by considering the edge effect as a superposition of skirt area diffusion and “blocking effect” and optimizing the edge effect for uniformity control of nanowire growth. We directly model the blocking effect of nanowires in the process of precursor diffusion from the skirt area to the center of a substrate. The improved model closely captures the distribution of the nanowire length across the substrate. Physical interpretation of the edge effect is provided. With the established model, we provide a method to optimize the width of the skirt area to improve the predicted structural uniformity of SA-MOCVD growth.

Selective metal-organic chemical vapor deposition growth of high quality GaAs on Si(001)

High quality GaAs is selectively grown in 40 nm width Shallow Trench Isolation patterned structures. The patterned wafers have a V-shape Si (111) surface obtained by Tetramethylammonium hydroxide etching. By employing a SiCoNi™ pre-epi clean and two-step growth procedure (low temperature buffer and high temperature main layer), defects are effectively confined at the trench bottom, leaving a dislocation-free GaAs layer at the upper part. The high crystal quality is confirmed by transmission electron microscopy. Scanning spreading resistance microscopy indicates a high resistance of GaAs. The process conditions and GaAs material quality are highly compatible with Si technology platform.

Formation and optical properties of multi-stack InGaAs quantum dots embedded in GaAs nanowires by selective metalorganic chemical vapor deposition

We report formation and optical properties of site-controlled, multi-stack InGaAs/GaAs quantum dots (QDs) embedded in GaAs nanowires (NWs) by selective metalorganic chemical vapor deposition. InGaAs/GaAs QDs are realized in GaAs NWs grown on patterned GaAs(111)B substrates in the form of InGaAs/GaAs heterostructures and identified by structural analyses and photoluminescence characterization. Optical characterization at 10K corroborates formation of high-quality, multi-stack InGaAs/GaAs QD-in-NWs up to 50-stack without degradation of PL intensities. In addition, light emission at room temperature from multi-stack InGaAs/GaAs QDs embedded in GaAs NWs is realized. These results would enable the realization of high-performance IBSCs based on site-controlled QD-in-NWs utilizing existing, well-established NW growth technologies on a GaAs platform.

Optical Properties of Site-Controlled InGaAs Quantum Dots Embedded in GaAs Nanowires by Selective Metalorganic Chemical Vapor Deposition

We report the optical properties of site-controlled InGaAs quantum dots (QDs) embedded in GaAs nanowires (NWs) grown by selective metalorganic chemical vapor deposition (MOCVD). InGaAs/GaAs QD-in-NWs with various QD heights and In compositions are realized on patterned GaAs(111)B substrates in the form of InGaAs/GaAs heterostructures, and identified by structural analyses using scanning transmission electron microscopy, photoluminescence (PL) characterization, and numerical analyses of the band structure using a single-band effective mass approximation. Room temperature (RT) light emission is observed at 1.03 µm from InGaAs/GaAs QD-in-NWs which is indicative of the formation of high-quality InGaAs QD-in-NWs. Sharp emission peaks from exciton and biexciton of single In(Ga)As QD-in-NWs are observed by using µ-PL characterization at 10 K.

Optical Properties of Site-Controlled InGaAs Quantum Dots Embedded in GaAs Nanowires by Selective Metalorganic Chemical Vapor Deposition

Optical Properties of Site-Controlled InGaAs Quantum Dots Embedded in GaAs Nanowires by Selective Metalorganic Chemical Vapor Deposition

Site-controlled formation of InAs/GaAs quantum-dot-in-nanowires for single photon emitters

We report the demonstration of site-controlled InAs/GaAs quantum dots (QDs) embedded in GaAs nanowires (NWs) by selective metalorganic chemical vapor deposition. InAs/GaAs quantum-dot-in-nanowires (QD-in-NWs) with various InAs thicknesses are realized on patterned GaAs(111)B substrates in the form of InAs/GaAs heterostructures and identified by structural analyses using scanning transmission electron microscopy and photoluminescence characterization. Sharp excitonic emission peaks at 10 K from single QD-in-NWs with the narrowest exciton linewidth of 87 μeV are observed. Light emission from the single QD-in-NW shows photon antibunching, along with biexciton-exciton cascaded emission process, which evidences single photon emission from high-quality QD-in-NWs.

Formation of a single In(Ga)As/GaAs quantum dot embedded in a site-controlled GaAs nanowire by metalorganic chemical vapor deposition for application to single photon sources

ABSTRACTWe report the formation and optical properties of site-controlled InAs/GaAs quantum dots (QDs) embedded in GaAs nanowires (NWs) by selective metalorganic chemical vapor deposition for application to single photon sources. InAs/GaAs QD-in-NWs with various InAs thicknesses are realized on patterned GaAs(111)B substrates in the form of InAs/GaAs heterostructures and identified by structural analyses using scanning transmission electron microscopy and photoluminescence characterization. Sharp excitonic emission peaks at 10 K from single QD-in-NWs with the narrowest exciton linewidth of 87 μeV are observed. Light emission from the single QD-in-NW shows photon antibunching which evidences single photon emission from high-quality QD-in-NWs.

Controlled growth of InGaAs/InGaAsP quantum dots on InP substrates employing diblock copolymer lithography

Selective metalorganic chemical vapor deposition growth with diblock copolymer nanopatterning is utilized to produce InGaAsP(Q1.15 μm)/In0.53Ga0.47As/InGaAsP(Q1.15 μm) and InP/In0.53Ga0.47As/InP quantum dots (QDs) on InP substrates. The QD patterning is prepared by dense nanoscale diblock copolymer lithography followed by pattern-transfer onto a dielectric template mask and reactive ion etching is utilized to form nanosized openings exposing the underlying InGaAsP layer. By varying the In0.53Ga0.47As layer thickness within the QDs, the emission wavelength can be selected within the 1.4–1.6 μm region. Strongest photoluminescence (PL) intensity is observed from QDs employing InP rather than InGaAsP barriers, demonstrating room temperature PL near 1.6 μm.

Ultrafine ZnO Nanowire Electronic Device Arrays Fabricated by Selective Metal–Organic Chemical Vapor Deposition

Fine art: Ultrafine ZnO nanowires selectively grown parallel to the substrate only on Au patterns allow the integration of large numbers of nanowire field-effect transistor arrays (see picture).

Improved GaN-Based LED Light Extraction Efficiencies via Selective MOCVD Using Peripheral Microhole Arrays

GaN-based light-emitting diodes with peripheral microhole arrays (PMA-LEDs) have been grown, and fabricated, on SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> hexagonal pattern masks using selective metal-organic chemical vapor deposition. The PMA-LED structure promises to enhance the light extraction efficiency via simple fabrication processes, as compared to conventional LED structures. The geometrical shape of the peripheral microhole structure serves to enhance the light extraction efficiency due to the effect of the PMA in facilitating multiple chances for photons to escape. Thus, the light output intensity of PMA-LED was 30% higher than that of conventional LEDs.

InGaAs/AlGaAs Quantum Wire DFB Laser by One-Time Selective MOCVD on Ridge Substrate

A quasi-buried hetero-structure (BH) quantum wire (QWR) distributed feedback (DFB) laser was realized by one time selective metalorganic chemical vapor deposition (MOCVD) on a ridge substrate with a sub-micron grating. One time selective MOCVD growth forms ridge waveguide with BH structure and a QWR array for gain guided DFB LD without additional etching or re-growth process. The threshold current is 15mA, and the threshold current density is 850A/cm2. A stable single longitudinal mode was preserved until 3 Ith, after which another mode emerged at higher drive current at 813.6nm. This suggests a complex coupled DFB mode operation. Elimination of the re-growth step also enlarges the selection of material for extended wavelength and operational temperature.

Selective MOCVD growth of single-crystal dense GaAs quantum dot array using cylinder-forming diblock copolymers

In order to realize the theoretical advantages of ideal quantum dots (QDs) (i.e., complete three-dimensional carrier confinement), an alternate approach to self-assembly has been investigated for elimination of the wetting layer and achieving a uniform mono-modal QD size distribution. On a GaAs substrate, hexagonally arranged uniform-sized QD arrays have been fabricated. The QD patterning is prepared by dense nanoscale diblock copolymer lithography, which consists of perpendicularly ordered cylindrical domains of polystyrene- block-poly(methylmethacrylate) (PS- b-PMMA) matrix. The polymer patterns are transferred to a dielectric template mask and then single-crystal GaAs QDs are selectively grown on the patterned substrate by metalorganic chemical vapor deposition (MOCVD). Single-crystal QDs are confirmed by X-ray diffraction with a large area detector. Scanning electron mocroscope images indicate that the QD density is larger than 5×10 10/cm 2, comparable to Stranski–Krastnow growth mode. Using the technique of diblock copolymer lithography followed by the selective MOCVD growth of the QDs, a higher degree of control of QD shape, size uniformity, and composition is expected.

InGaAs/AlGaAs Quantum Wire DFB Buried HeteroStructure Laser Diode by One-Time Selective MOCVD on Ridge Substrate

A quasi-buried heterostructure (BH) quantum wire (QWR)-distributed feedback (DFB) laser was realized by one-time selective metalorganic chemical vapor deposition (MOCVD) on a ridge substrate with a submicron grating. One-time selective MOCVD led to the formation of a ridge waveguide with a BH structure and a QWR array for gain-guided DFB laser diode (LD) without additional etching or regrowth process. The threshold current is 15 mA, and the threshold current density is 850 A/cm2. A stable single longitudinal mode was preserved until 3 Ith, after which another mode emerged at a high drive current at 813.6 nm. This suggests a complex-coupled DFB-mode operation. The elimination of the regrowth step enlarges the range of material for extended wavelengths and operational temperatures.

GaAs pyramidal microtips grown by selective liquid-phase epitaxy

We present a simple selective liquid-phase epitaxial growth of GaAs pyramidal microtips for integrated scanning near-field optical microscopy sensors. The technique comprises oxide mask formation, openings creation, and liquid-phase epitaxial growth. SiO2 mask is firstly formed on (001) GaAs substrate by liquid-phase deposition, periodic square windows are then created in the mask using photolithography and wet etching, and GaAs microtips are finally grown on the opening areas by liquid-phase epitaxy. Scanning electron microscopy images show high quality of the pyramidal microtips bounded by four equal {111} sidewalls. This differs greatly from those drawn from selective metalorganic chemical vapor deposition.

AlGaAs/InGaAs DFB Laser by One-Time Selective MOCVD Growth on a Grating Substrate

A gain-coupled distributed feedback (DFB) laser is realized using a high-density InGaAs/AlGaAs quantum wire (QWR) array formed within a finite area of 6×500 µm by electron beam lithography and one-time selective metalorganic chemical vapor deposition (MOCVD). The stable gain-coupled DFB mode is confirmed at 812 and 830 nm from the 360 and 370 nm pitch gratings, respectively. The mode analysis of the actual cross-sectional structure using a finite element method verified that modal gain has a single peak at the Bragg wavelength of the grating.

Area-Controlled Growth of InAs Quantum Dots by Selective MOCVD

A technique to control the location of quantum dot growth is required to avoid optical absorption and attain high reflectivity in fabricating quantum dot lasers with photonic crystal reflectors in the same growth plane as the active layer. In this paper, we demonstrate a novel scheme for area-controlled growth of quantum dots using selective metal organic chemical vapor deposition (MOCVD). Using this technique, the deposition of material within mask windows can be controlled by varying the width of the SiO2 mask. By optimizing the growth conditions and mask pattern, a high density (2.4×1011/cm2) of quantum dots was formed selectively only in the active layer of a laser structure, while no quantum dots were formed in the reflector region.

Seeded self-assembled GaAs quantum dots grown in two-dimensional V grooves by selective metal–organic chemical-vapor deposition

We propose and demonstrate a seeded self-assembling growth technique for the fabrication of quantum dot structures by metal–organic chemical-vapor deposition. GaAs quantum dots were grown at the bottom of two-dimensional V-groove (2DVG) structures, which were composed of (111)A and (111)B facets on a GaAs(100) substrate. The 2DVG was grown by selective growth on a SiO2 patterned substrate. It was found that vertical GaAs quantum wires were also simultaneously formed in the 2DVGs. Using this technique, the stacking of GaAs quantum dots was realized. Photoluminescence and cathodoluminescence from each structure evidenced the formation of both the quantum wires and the quantum dots.

Structural dependence of 1.3-μm narrow-beam lasers fabricated by selective MOCVD growth

The effect of structural parameters on the lasing characteristics of 1.3-/spl mu/m narrow beam lasers has been investigated. Monolithically integrated vertically tapered multiquantum-well (MQW) waveguide, fabricated by use of selective metal-organic chemical vapor deposition (MOCVD), is used for the expansion of the optical spot size. It is experimentally shown that the energy separation between the gain and waveguide regions that is formed simultaneously by selective MOCVD is shown to be an important parameter in order to achieve low-threshold current density and good temperature characteristics. The lengths of gain and waveguide regions have been investigated in terms of temperature characteristics of threshold current and far-field angle. A lower threshold current density and a higher characteristic temperature were obtained for longer gain region, We also have estimated the waveguide loss of the mode-field converter lasers diodes (MFC-LD's). High performance of 1.3-/spl mu/m integrated vertically tapered waveguide lasers were achieved in an optimized device.

Fabrication and microscopic photoluminescence imaging of ridge-type InGaAs quantum wires grown on a (110) cleaved plane of AlGaAs/GaAs superlattice

We have fabricated ridge-type InGaAs quantum wire structures on a (110) cleaved plane of AlGaAs/GaAs superlattice using selective metalorganic chemical vapor deposition growth. The lateral width of the quantum wires was about 25 nm. Spatially resolved photoluminescence (PL) of the quantum wires was observed by using microscopic photoluminescence measurement at low temperature, showing PL from the quantum wire region and its polarization dependence.

Monolithic integration of AlGaAs/GaAs HBT and GaAs junction-gate floated electron channel field effect transistor using selective MOCVD growth

A novel GaAs BiFET structure based on AlGaAs/GaAs HBT and GaAs junction-gate floated electron channel field effect transistor (J-FECFET) has been developed. Selective metalorganic chemical vapor deposition (MOCVD) growth is extensively used for the BiFET. Structural advantage of the BiFET is that the epitaxial layers of the J-FECFET are identical to the lower part of a conventional heterojunction bipolar transistor (HBT). Transconductance of the fabricated J-FECFET with 1×200 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> gate is 102 mS/mm with f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> and f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 10.7 GHz and 27.3 GHz, respectively. DC current gain of HBT is 21 at a collector current density of 50 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with emitter area of 3×2 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The new integration technology offer a foundation for development of various multifunction monolithic microwave integrated circuits (MMIC's).