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The direct integration of epitaxial III-V and III-N heterostructures on Si substrates is a promising platform for the development of optoelectronic devices. Nanowires, due to their unique geometry, allow for the direct synthesis of semiconductor light-emitting diodes (LED) on crystalline lattice-mismatched Si wafers. Here, we present molecular beam epitaxy of regular arrays n-GaN/i-InGaN/p-GaN heterostructured nanowires and tripods on Si/SiO2 substrates prepatterned with the use of cost-effective and rapid microsphere optical lithography. This approach provides the selective-area synthesis of the ordered nanowire arrays on large-area Si substrates. We experimentally show that the n-GaN NWs/n-Si interface demonstrates rectifying behavior and the fabricated n-GaN/i-InGaN/p-GaN NWs-based LEDs have electroluminescence in the broad spectral range, with a maximum near 500 nm, which can be employed for multicolor or white light screen development. [ABSTRACT FROM AUTHOR]

An array of GaN nanowires (NWs) on Si substrate is synthesized by molecular beam epitaxy. Measurements of electrical properties at room temperature of single NWs transferred to an auxiliary substrate demonstrate that the current density reaches an extremely high level of 2 MA cm−2 without NW damage. Taking into account the limited conductivity of the NW periphery due to electron surface states, that is, the conduction channel narrowing, the effective current density can reach 3 MA cm−2. [ABSTRACT FROM AUTHOR]

III–V/Si integration is one of the bottlenecks of modern semiconductor technology. Dilute nitride phosphides (III–P–N) are among the promising materials providing lattice matching with Si. In this work, we study the effect of growth conditions on the chemical composition and properties of GaP1−xNx/GaP/Si planar heterostructures synthesized by plasma assisted molecular beam epitaxy. A series of samples with a maximum fraction of incorporated nitrogen as high as 5.05% is synthesized. The morphological, structural and optical properties of the heterostructures are studied. The tendency towards 3D growth and microtwinning in dilute nitride layers are demonstrated with the increase of nitrogen content. The most intense room temperature (RT) red photoluminescence (PL) emission is obtained with the sample containing 3.07% N. The PL intensity is found to be dependent on the N growth flux while its content only slightly changes with the flux. A low temperature PL study demonstrates efficient donor–acceptor recombination in the synthesized samples. Despite low structural perfection, the sample with the highest nitrogen content demonstrates PL response at RT centered at 1.76 eV. [ABSTRACT FROM AUTHOR]

We demonstrate flexible red light-emitting diodes based on axial GaPAs/GaP heterostructured nanowires embedded in polydimethylsiloxane membranes with transparent electrodes involving single-walled carbon nanotubes. The GaPAs/GaP axial nanowire arrays were grown by molecular beam epitaxy, encapsulated into a polydimethylsiloxane film, and then released from the growth substrate. The fabricated free-standing membrane of light-emitting diodes with contacts of single-walled carbon nanotube films has the main electroluminescence line at 670 nm. Membrane-based light-emitting diodes (LEDs) were compared with GaPAs/GaP NW array LED devices processed directly on Si growth substrate revealing similar electroluminescence properties. Demonstrated membrane-based red LEDs are opening an avenue for flexible full color inorganic devices. [ABSTRACT FROM AUTHOR]

Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam epitaxy. We report the approach to form the silicon oxide layer, which reproducibly provides a high yield of vertical GaP NWs and control over the NW surface density without a pre-patterned growth mask. Above that, we present the strategy for controlling both GaP NW length and diameter independently in single- or two-staged self-catalyzed growth. The proposed approach can be extended to other III-V NWs. [ABSTRACT FROM AUTHOR]

Control and analysis of the crystal phase in semiconductor nanowires are of high importance due to the new possibilities for strain and band gap engineering for advanced nanoelectronic and nanophotonic devices. In this letter, we report the growth of the self-catalyzed GaP nanowires with a high concentration of wurtzite phase by molecular beam epitaxy on Si (111) and investigate their crystallinity. Varying the growth temperature and V/III flux ratio, we obtained wurtzite polytype segments with thicknesses in the range from several tens to 500 nm, which demonstrates the high potential of the phase bandgap engineering with highly crystalline self-catalyzed phosphide nanowires. The formation of rotational twins and wurtzite polymorph in vertical nanowires was observed through complex approach based on transmission electron microscopy, powder X-ray diffraction, and reciprocal space mapping. The phase composition, volume fraction of the crystalline phases, and wurtzite GaP lattice parameters were analyzed for the nanowires detached from the substrate. It is shown that the wurtzite phase formation occurs only in the vertically-oriented nanowires during vapor-liquid-solid growth, while the wurtzite phase is absent in GaP islands parasitically grown via the vapor-solid mechanism. The proposed approach can be used for the quantitative evaluation of the mean volume fraction of polytypic phase segments in heterostructured nanowires that are highly desirable for the optimization of growth technologies. [ABSTRACT FROM AUTHOR]

Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and structural properties were examined by means of Raman microspectroscopy and transmission electron microscopy. To study the optical properties of the synthesized nanoheterostructures, the nanowire array was embedded into the silicone rubber membrane and further released from the growth substrate. The reported approach allows us to study the nanowire optical properties avoiding the response from the parasitically grown island layer. Photoluminescence and Raman studies reveal different nitrogen content in nanowires and parasitic island layer. The effect is discussed in terms of the difference in vapor solid and vapor liquid solid growth mechanisms. Photoluminescence studies at low temperature (5K) demonstrate the transition to the quasi-direct gap in the nanowires typical for diluted nitrides with low N-content. The bright room temperature photoluminescent response demonstrates the potential application of nanowire/polymer matrix in flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

In the paper, the influence of growth factors and silicon surface condition on the epitaxial formation of single-domain GaP buffer layers on Si (001) has been studied. A novel two-stage growth technique for the epitaxial building-up of this structure has been put forward and developed. In contrast to using the migration enhanced epitaxy technique, the proposed technology allows one to separate the nucleation and growth stages, to control the doping profile of the GaP buffer layers. The latter is important for further functional applications. The main factors determining the orientation of GaP crystalline lattice when it nucleates on the Si vicinal surface were found. The structural perfection of the grown buffer layers at both stages was proved through careful control by TEM, RHEED, AFM, and HRXRD. These findings have important implications for further functional applications.

Efficient doping of semiconductor nanowires remains a major challenge towards the commercialization of nanowire-based devices. In this work we investigate the growth regimes and electrical properties of MBE-grown p- and n-type gallium phosphide nanowires doped with Be and Si, respectively. Electrical conductivity of individual nanowires is quantitatively studied via atomic force microscopy supported with numerical analysis. Based on conductivity measurements, we provide growth strategies for achieving the doping level up to N D =5⋅1018 cm-3 and N A =2⋅1019 cm-3 for GaP:Si and GaP:Be nanowires respectively, which is high enough for technological applications. [ABSTRACT FROM AUTHOR]

Progress in monolithic integration of III-V semiconductor heterostructures on silicon promotes the development of silicon-based integrated optoelectronics. Here, we report on the fabrication of dual-functional light-emitting and photo-detecting heterostructures based on aluminum-free quaternary dilute nitride alloys of GaAsPN, epitaxially grown on silicon wafers, operating in the red part of the visible spectrum. The use of indirect band gap GaP cladding layers minimizes light absorption and simplify fabrication technology. The low-temperature grown GaP/AlGaP nucleation layer has been employed to achieve antiphase domain-free growth of GaP on Si (001). Quaternary GaAsPN alloy layers with bandgap values, ranging from 1.94 to 1.83 eV, were grown by plasma-assisted molecular beam epitaxy at a high temperature of 540 °C, which ensures high crystallinity. The influence of growth conditions on the GaAsPN alloy composition, structure and optoelectronic properties is discussed. The fabricated p-i-n mesa diodes demonstrate low leakage currents and both photocurrent response with an external quantum efficiency in the range of 30–42% and bright red interband electroluminescence at room temperature. [Display omitted] • GaAsPN on Si pin heterostructures show light emission and detection functionality. • High temperature PA-MBE growth provides structural perfection and E g tunability. • Simple two-step procedure provides antiphase domain-free III-V/Si heteroepitaxy. • Bright red electroluminescence at 300 K and low leakage current demonstrated. • Photovoltaic external quantum efficiency of 42% achieved. [ABSTRACT FROM AUTHOR]

Gallium phosphide is an important material in terms of III-V semiconductors integration on Si. In this work we study photovoltaic properties of GaP:Be/GaNP (E g ~ 2.0eV)/GaP:Si p-i-n heterostructure grown on Si (100) with GaP buffer by plasma-assisted molecular beam epitaxy. Correlation between the structural and optoelectronic properties of the fabricated device was studied by scanning and transmission electron microscopy (TEM), electron beam induced current (EBIC) and deep-level transient spectroscopy (DLTS) techniques. The I–V characteristic of the fabricated mesa diode demonstrates short circuit current of 2.2 mA/cm2 and open circuit voltage of 0.8 V. TEM studies of the epilayer structural properties demonstrate high density of antiphase domains in the n-doped GaP buffer layer; however, they found to be annihilated in dilute nitride layer, where mainly threading dislocations were formed. EBIC investigation shows that crystalline imperfections of the heterostructure leads to poor carriers transport affecting the energy conversion efficiency. We performed numerical modeling concerning presence of the structural defects and discuss their influence on the diode performance. The carried out study is the initial step on the way to development of the growth technique of the GaP-based dilute nitride direct bandgap materials on Si for photonic and photovoltaic applications. • For the first time MBE-grown GaNP-based solar cell on Si is fabricated. • The fabricated device is thoroughly characterized with I–V, DLTS and EBIC measurements. • Theoretical model of the device is introduced to find out prospects for future development of the photovoltaic devices of the proposed design. [ABSTRACT FROM AUTHOR]