Gas Source Molecular Beam Epitaxy Research Articles

Selective Growth of GaP Crystals on CMOS-Compatible Si Nanotip Wafers by Gas Source Molecular Beam Epitaxy.

Gallium phosphide (GaP) is a III-V semiconductor with remarkable optoelectronic properties, and it has almost the same lattice constant as silicon (Si). However, to date, the monolithic and large-scale integration of GaP devices with silicon remains challenging. In this study, we present a nanoheteroepitaxy approach using gas-source molecular-beam epitaxy for selective growth of GaP islands on Si nanotips, which were fabricated using complementary metal-oxide semiconductor (CMOS) technology on a 200 mm n-type Si(001) wafer. Our results show that GaP islands with sizes on the order of hundreds of nanometers can be successfully grown on CMOS-compatible wafers. These islands exhibit a zinc-blende phase and possess optoelectronic properties similar to those of a high-quality epitaxial GaP layer. This result marks a notable advancement in the seamless integration of GaP-based devices with high scalability into Si nanotechnology and integrated optoelectronics.

Diffusion models of grown-in and implanted p-type dopant in III-V semiconductor compounds

This research shows that the diffusion of grown-in and implanted Be atoms in III-V considered semiconductor materials, such as the Liquid-Encapsulated Czochralski-grown (LEC) GaAs as well as the Gas-Source Molecular Beam Epitaxy (GSMBE) In0.53Ga0.47As, In0.73Ga0.27As0.58P0.42, In0.53Ga0.47As/In0.73Ga0.27As0.58P0.42, In0.53Ga0.47As/InP compounds, taking place during the Rapid Thermal Annealing (RTA) process, is perfectly well explained by the “full” version of the kick-out mechanism operating through singly positively ionized Be interstitials and group III self-interstitial ions (Ga, In) in all their states of positive charge including neutral. Numerical solutions of the differential equations, corresponding to the considered system of diffusion reactions, have been calculated using the finite difference approach and our elaborate finite difference-Bairstow method. Such a model naturally emerges from most research works, including ours, in the considered field, over the last decades and makes it possible to “reconcile” their different diffusion models. In this study, we also present and analyze the Secondary Ion Mass Spectrometry (SIMS) profiles of the distribution of implanted Be in GaAs at an energy of 100 keV with a high dose of 1.0 ⋅ 1015cm−2 and annealed at temperatures ranging from 700 to 850 °C for à time ranging from 60 to 240s.

Phonon Characteristics of Gas-Source Molecular Beam Epitaxy-Grown InAs1−xNx/InP (001) with Identification of Si, Mg and C Impurities in InAs and InN

The lattice dynamical properties of dilute InAs1−xNx/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θi = 0). The results in the frequency range of 180–500 cm−1 revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs1−xNx alloys, a classical “Drude–Lorentz” model was constructed to obtain the dielectric functions ε~ω in the far IR regions by incorporating InAs-like and InN-like transverse optical ωTO modes. Longitudinal optical ωLO phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs1−xNx/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θi ≠ 0), our study of s- and p-polarized reflectance (Rs,p(ω)) and transmission (Ts,p(ω)) spectra allowed the simultaneous perception of the ωTO and ωLO phonons of the InAs, InN and InAs0.97N0.03 layers. Based on the average t-matrix Green’s function theory, the results of local vibrational modes for light SiIn+ donors and SiAs−, CAs− acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. InInN, however, the method predicted an in-band mode for the MgIn− acceptor while projecting an impurity mode of the SiIn+ donor to appear just above the maximum ωmaxInN[≡595 cm−1] phonon frequency region. In InAs1−xNx/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors.

Systematic Assessment of Phonon and Optical Characteristics for Gas-Source Molecular Beam Epitaxy-Grown InP1−xSbx/n-InAs Epifilms

Experimental and theoretical assessments of phonon and optical characteristics are methodically accomplished for comprehending the vibrational, structural, and electronic behavior of InP1−xSbx/n-InAs samples grown by Gas-Source Molecular Beam Epitaxy. While the polarization-dependent Raman scattering measurements revealed InP-like doublet covering optical modes (ωLOInP~350 cm−1, ωTOInP~304 cm−1) and phonons activated by disorders and impurities, a single unresolved InSb-like broadband is detected near ~195 cm−1. In InP1−xSbx, although no local vibrational (InSb:P; x → 1) and gap modes (InP:Sb; x → 0) are observed, the Raman line shapes exhibited large separation between the optical phonons of its binary counterparts, showing features similar to the phonon density of states, confirming “two-mode-behavior”. Despite the earlier suggestions of large miscibility gaps in InP1−xSbx epilayers for x between 0.02 and 0.97, our photoluminescence (PL) results of energy gaps insinuated achieving high-quality single-phase epilayers with x ~ 0.3 in the miscibility gap. Complete sets of model dielectric functions (MDFs) are obtained for simulating the optical constants of binary InP, InSb, and ternary InP1−xSbx alloys in the photon energy (0 ≤ E ≤ 6 eV) region. Detailed MDF analyses of refractive indices, extinction coefficients, absorption and reflectance spectra have exhibited results in good agreement with the spectroscopic ellipsometry data. For InP0.67Sb0.33 alloy, our calculated lowest energy bandgap E0 ~ 0.46 eV has validated the existing first-principles calculation and PL data. We feel that our results on Raman scattering, PL measurements, and simulations of optical constants provide valuable information for the vibrational and optical traits of InP1−xSbx/n-InAs epilayers and can be extended to many other technologically important materials.

Structural and optical properties of InP1-xSbx/n-InAs epilayers grown by gas source molecular beam epitaxy

High-resolution x-ray diffraction (HR-XRD), photoluminescence (PL), synchrotron radiation extended x-ray absorption fine-structure (SR-EXAFS) measurements are methodically analyzed for assessing the optical and structural properties of InP1−xSbx/n-InAs epifilms grown by gas-source molecular-beam epitaxy method. For InP0.63Sb0.37/n-InAs sample, the PL study has revealed two A1, A2 energy bands. The A1 band prevalent at low temperature is attributed to the recombination of carriers trapped in the tail states. The A2 band with nearly constant transition energy ∼ 0.46 eV is virtually temperature independent. In InP1−xSbx alloys, the energy peak of A1 band redshifted with temperature and showed strong compositional disorder. The A2 band, dominant at higher temperature with Gaussian-like line shape is ascribed to the deep-level transition as its behavior coincided with the signature of a configuration coordinate model. The deep level responsible for A2 band is possibly linked to the “vacancy-impurity” like complexes having ground and excited states in the energy band gap. The composition dependent analysis of SR-EXAFS data for InP1−xSbx/InAs samples has confirmed the maintenance of nearest neighbor In-P, In-Sb shell distances within the range of bulk binary materials’ bond lengths. We feel that our results of HR-XRD, PL and SR-EXAFS techniques have provided valuable information on the structural and optical characteristics of the InP1−xSbx/n-InAs (001) epilayers and can be extended to many other technologically important materials.

Gallium Phosphide Nanowires Grown on SiO2 by Gas-Source Molecular Beam Epitaxy

GaP as one of the III–V semiconductors has an indirect band gap in its natural zinc-blend (ZB) crystal phase, limiting its applications in optoelectronics. The atomic arrangements of the ZB GaP, however, can be changed by adding energy to the system, for example, using strain and defects. In such a way, GaP can be crystallized in the wurtzite (WZ) phase with a direct band gap in the yellow–green range and promising new optical properties. GaP nanostructures offer the great possibility to induce strain, and hence, one can expect to obtain the WZ phase by modifying the geometry and dimensionality of GaP. In this work, we present GaP nanowires (NWs) grown on SiO2 substrates by gas-source molecular beam epitaxy. Raman measurements on individual GaP NWs indicate that NWs are poly-type crystal structures with the starting growth of the WZ phase, transforming into the ZB phase, and ending as the WZ phase. Photoluminescence at 9 K from an ensemble of NWs shows emissions at 2.09–2.14 eV, which are related to the direct band gap of the WZ phase and peaks between 2.26 and 2.3 eV due to the ZB phase. The emission of the WZ GaP phase is observable up to 160 K. Cathodoluminescence at 83 K shows directly the emission between 2.09 and 2.14 eV along the single NWs, indicating the presence of the WZ phase. Our results demonstrate the realization of poly-type, ZB, and WZ GaP NWs on SiO2 by gas-source molecular beam epitaxy.

Magnetic and transport properties of electron doped EuTiO3 thin films with La3+ (4f) or Gd3+ (4f7) donors grown by gas source molecular beam epitaxy

EuTiO3 (ETO) is a unique magnetic semiconductor with a large localized magnetic moment of Eu2+ (4f 7). By the doping of high-mobility electrons in the Ti 3d conduction band, peculiar magnetotransport properties such as the unconventional anomalous Hall effect (AHE) due to Berry curvature in momentum space, as well as the Shubnikov–de Haas oscillations of spin polarized electrons, have been observed. In this study, we have examined the physical properties of high quality ETO films with La3+ (4f0) or Gd3+ (4f7) donors (ELTO or EGTO) grown on nearly lattice matched SrTiO3 substrates with a gas source molecular beam epitaxy. We find that the anti-ferromagnetic ordering of ELTO is destabilized by the vacancy of the magnetic moment on the La-site for ELTO. The maximum electron mobility for ELTO (<3200 cm2 V−1 s−1) is larger than that of EGTO (<1500 cm2 V−1 s−1), keeping the metallic state at very diluted doping. The AHE changes its sign with shifting the Fermi level position across the Weyl nodes, as seen previously for compressively strained ELTO films, but the critical electron density is much lower, which can be explained by the absence of additional crystal-field splitting in the lattice matched system. These unveiled transport properties provide deeper understanding of the transport phenomena related to the topology of the band structure in high-mobility, magnetic oxide semiconductors.

Molecular beam epitaxial growth of multilayer 2D-boron nitride on Ni substrates from borazine and plasma-activated nitrogen

2D boron nitride (2D-BN) was synthesized by gas-source molecular beam epitaxy on polycrystalline and monocrystalline Ni substrates using gaseous borazine and active nitrogen generated by a remote plasma source. The excess of nitrogen atoms allows to overcome the thickness self-limitation active on Ni when using borazine alone. The nucleation density and the shape of the 2D-BN domains are clearly related to the Ni substrate preparation and to the growth parameters. Based on spatially-resolved photoemission spectroscopy and on the detection of the π plasmon peak, we discuss the origin of the N1s and B1s components and their relationship with an electronic coupling at the interface. After optimization of the growth parameters, a full 2D-BN coverage is obtained, although the material thickness is not evenly distributed. The 2D-BN presents a granular structure on (111) oriented Ni grains, showing a rather poor cristallographic quality. On the contrary, high quality 2D-BN is found on (101) and (001) Ni grains, where triangular islands are observed whose lateral size is limited to ∼20 μm.

Increasing the critical thickness of SiGe layers on Si substrates using sputter epitaxy method

SiGe layers were formed on Si substrates by using the sputter epitaxy method. The growth temperatures were 400 and 560 °C, and the growth rates of the SiGe layers were about 2.7–5.4 nm/min, depending on the Ge composition ratio. The samples formed by gas-source molecular beam epitaxy (GSMBE) were also fabricated for comparison. The lattice-mismatch ratio was investigated using X-ray diffraction, the surface roughness was observed by an atomic force microscope, and the crystallinity of the SiGe layers was observed by a transmission electron microscope. The critical thickness of the SiGe layers was estimated from the lattice-mismatch ratio, and the critical thickness at a growth temperature of 400 °C was higher than that in the GSMBE and previous reports. The surface roughness of the Si1-xGex layers (x = 0.24–0.51) with no strain relaxation was flat and below 1 nm. Without any buffer techniques, high Ge content SiGe layers with no strain relaxation were directly formed on Si substrates using the sputter epitaxy method. It is considered that the sputter epitaxy method can grow SiGe layers at relatively low temperatures and can increase the critical thickness.

(Invited) Low-Temperature Spatially-Resolved Luminescence Spectroscopy of Microstructures with Strained III-V Quantum Wells

The continuous development of advanced photonic devices based on 3-dimensional structuring of active materials calls for more efforts on characterization techniques. This statement applies, in particular, to processes, such as dry etching applied to III-V semiconductors. Dry (or plasma-based) etching is frequently used within nanofabrication platforms to realize semiconductor lasers, ridge waveguides, photonic integrated circuits, etc. Luminescence techniques (photo-luminescence or cathodo-luminescence) can analyze the material’s properties after dry etching, especially for direct band-gap semiconductors. The presence of non-radiative defects, changes in the local stress/strain, etc., can be probed in detail owing to the spatial resolution of this class of techniques, and their quantification can also be addressed. Our goal in this work is to highlight a robust methodology involving the design of specific test materials, including a series of different quantum wells (QWs) located at well-defined depths below the surface. The spectroscopic signature of these QWs provides valuable information, which can be used to assess the changes occurring to the III-V semiconductor material due to dry etching.The test structures have been designed on (100)-oriented InP substrates, with alternating InAsxP1-x QWs and InP barriers. Sequences of typically 8 QWs with graded As composition were grown, with a fixed thickness (7 to 8 nm), separated by 100 nm InP barriers. The shallowest QW is located 300 nm below the sample surface. By grading the As composition in the QWs (with x typically between 0.35 and 0.5), the luminescence signal for each QW could be unambiguously identified with sharp lines when measured at very low temperatures. These structures were grown by gas-source molecular beam epitaxy. Figure 1 illustrates such a structure.In a second step, a SiNx film was deposited by plasma-enhanced chemical vapor deposition and patterned using standard optical lithography. Elongated stripes were thus defined, whose width varies between 1 and 50 µm, and length is a few mm. Finally, plasma etching was used to fabricate stripes within the QW structures, using this SiNx film as a hard mask. Based on Cl2/CH4/Ar and H2/CH4/Ar, different gas mixtures were employed to perform this etching.We have characterized these etched stripes by micro-PL at 10 K in a specially designed optical cryostat, allowing a spatial resolution of approximately 1 µm and a step-size of 5 µm for mapping the luminescence signal. A 1064 nm laser source was chosen for the excitation of the PL signal in our samples. The choice of this wavelength allows selective excitation of the QWs, avoiding excitation of the InP barrier material. As shown in figure 2, the spectrum displays well-identified lines, which can be attributed clearly to the different QWs in the sample. The very sharp lines (full width at half maximum of the order of 4 meV) attest to the very high sample quality. A fitting procedure was implemented to determine the spectral characteristics of each transition, as illustrated by the red line (“Model”) in fig. 2-a. We have established ([1]) that the observed PL lines are associated with single optical transitions in each QW between the electron and the heavy-hole levels. The transition energies scale linearly with the As composition in each QW (fig. 2-b).By scanning across the etched stripes, we could determine the local changes of the spectral parameters for each QW line as a function of the laser beam position. The first observation is that the etching processes do not introduce any spectral broadening of the PL lines. In fact, for some of the etching processes evaluated, a sharpening of the lines is even observed. This is in contrast with the general assumption that dry etching produces some disorder-induced PL line broadening. The line positions are almost not affected by the etching processes. Finally, we observe some changes in the intensities of the QW lines across the stripes: these intensities decrease strongly near the edges. The different etching processes induce a different magnitude for this effect. These trends will be analyzed in terms of the modifications introduced within the etched material in the area close to the stripe edges. In some cases, the lateral extension of these modifications can reach 10 µm or more.[1] J. P. Landesman, N. Isik-Goktas, R. R. LaPierre, C. Levallois, S. Ghanad-Tavakoli, E. Pargon, C. Petit-Etienne and J. Jiménez, J. Phys. D: Appl. Phys. 54, 445106 (2021). Figure 1

Effect of Thickness of InP Nucleation Layer on the Two-Step Growth of InP on Si(001)

InP nucleation layers with different thicknesses were grown on Si(001) substrates by gas-source molecular beam epitaxy (GSMBE), and the two-step growth technique was used to overcome the large lattice mismatch (8%) between the InP nucleation layer and Si substrate. The surface morphology and microstructure were investigated by using an atomic force microscope (AFM) and transmission electron microscopy (TEM). High-resolution X-ray diffraction (HR-XRD) measurements were carried out to characterize the crystal quality. It was found that a too thin nucleation layer will lead to an uneven distribution of atoms on the surface, resulting in a poor crystalline quality of the InP epitaxial layer. The thicker the low-temperature nucleation layer is, the better the crystallization quality of the InP high-temperature layer will be.

Structure parameters design of InP based high electron mobility transistor epitaxial materials to improve radiation-resistance ability

In order to improve the radiation-resistance ability of the InP based high electron mobility transistor (InP HEMT) by optimizing the epitaxial structure design, a series of InP HEMT epitaxial structure materials with different structure parameters is grown by gas source molecular beam epitaxy. These samples are irradiated at room temperature by a 1.5-MeV electron beam at the same irradiation fluence of 2 × 10<sup>15</sup> cm<sup>–2</sup>. The electrical properties of the two-dimensional electron gas (2DEG) for InP HEMT epitaxial materials before and after irradiation are measured by Hall measurements to obtain the changes of the normalized 2DEG density and electron mobility along with the epitaxial structure parameters. The relation between 2DEG radiation damage and epitaxial structure parameters (such as Si-δ-doping density, spacer thickness, channel thickness and channel In content) of InP HEMT epitaxial structure materials is analyzed. The results show that the 2DEG of the InP HEMT epitaxial structure material with higher Si-δ-doping density, thinner spacer thickness, thicker channel thickness and lower channel In content has lower radiation damage, which possesses the stronger radiation-resistance ability.

The optimization of InGaAs/InGaP quantum wells grown by gas source molecular beam epitaxy

We report on the great improvement of optical properties of a InGaAs quantum well structure by inserting ultra-thin GaAs layers between the InGaAs well and the InGaP barrier grown by molecular beam epitaxy. The room temperature photoluminescence from the quantum well structure with insertion of 3 monolayers GaAs shows 1.5 times enhancement in peak intensity, as well as a drastic reduction of peak linewidth from 46 nm to 30 nm. The dependence of the quantum well optical properties has been investigated with inserted GaAs thickness in the range of 0–12 MLs, and optimized GaAs thickness has been obtained. This methodology might be beneficial for growth of high quality quantum well optical devices.

InGaAsPBi grown on InP substrate by gas source molecular beam epitaxy

The effects of growth condition on material quality of quinary alloy InGaAsPBi grown by gas source molecular beam epitaxy (GSMBE) were investigated systematically. It is found that 0.1% of Bi incorporation can play the role of surfactant effects and is beneficial to improve the material quality. The roughness of surface RMS measured by atomic force microscope (AFM) is 0.218 nm. Furthermore, the addition of a small amount of bismuth atoms promotes the binding of phosphorus atoms to group III atmos.

Conformal Growth of Radial InGaAs Quantum Wells in GaAs Nanowires.

GaAs-InGaAs-GaAs core-shell-shell nanowire (NW) structures were grown by gas source molecular beam epitaxy using the selective-area, self-assisted, vapor-liquid-solid method. The structural, morphological, and optical properties of the NWs were examined for different growth conditions of the InGaAs shell. With increasing In concentration of the InGaAs shell, the growth transitioned from preferential deposition at the NW base to the Stranski-Krastanov growth mode where InGaAs islands formed along the NW length. This trend is explained within a nucleation model where there is a critical In flux below which the conformal growth is suppressed and the shell forms only at the NW base. Low growth temperature produced a more uniform In distribution along the NW length but resulted in quenching of the photoluminescence (PL) emission. Alternatively, reducing the shell thickness and increasing the V/III flux ratio resulted in conformal InGaAs shell growth and quantum dot-like PL emission. Our results indicate a pathway toward the conditions for conformal InGaAs shell growth required for satisfactory optoelectronic performance.

Characterization of low-resistance ohmic contacts to heavily carbon-doped n-type InGaAsBi films treated by rapid thermal annealing* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11705277 and 61434006) and the Project of Hubei University of Arts and Science (Grant No. XK2019053).

Carbon-doped InGaAsBi films on InP:Fe (100) substrates have been grown by gas source molecular beam epitaxy (GSMBE). The electrical properties and non-alloyed Ti/Pt/Au contact resistance of n-type carbon-doped InGaAsBi films were characterized by Van der Pauw–Hall measurement and transmission line method (TLM) with and without rapid thermal annealing (RTA). It was found that the specific contact resistance decreases gradually with the increase of carrier concentration. The electron concentration exhibits a sharp increase, and the specific contact resistance shows a noticeable reduction after RTA. With RTA, the InGaAsBi film grown under CBr4 supply pressure of 0.18 Torr exhibited a high electron concentration of 1.6 × 1021 cm−3 and achieved an ultra-low specific contact resistance of 1 × 10−8 Ω⋅cm2, revealing that contact resistance depends greatly on the tunneling effect.

Versatile Externally Modulated Lasers Technology for Multiple Telecommunication Applications

This paper presents our technological approach for Externally Modulated Lasers (EMLs), based on Semi-Insulating Buried Heterostructure (SIBH) waveguide. We use Gas Source Molecular Beam Epitaxy (GSMBE) to grow the Phosphorus-based multi-quantum wells for both laser and modulator sections with butt-joint integration. The same GSMBE grows the p-doped InP claddings with low-diffusion Be dopant, leading to an accurate control of doping profiles, ensuring very steep modulator extinction curves. We present the main EML design rules and compromises, then apply them to different EMLs aiming at major telecom and datacom applications. After presenting characteristics of the standard 10 Gb/s C-band EML, we propose a 10 Gb/s EML at 1577 nm for next generation access networks, with a record high 10.5 dBm facet modulated power. Then we present high-speed EMLs up to 56 GBaud for datacenter interconnections, both in O- and C-band, aiming at very low peak-to-peak modulation voltage (<; 1.2 V), high facet modulated power (> 4.4 dBm), and compatible with uncooled operation (20 to 70 °C). These results confirm the efficiency and versatility of this technological platform for EMLs in a broad range of applications.

Si-matched BxGa1−xP grown via hybrid solid- and gas-source molecular beam epitaxy

The growth of BxGa1−xP alloys by hybrid solid/gas-source molecular beam epitaxy, with B supplied via the BCl3 gas precursor, is demonstrated. Compositional control ranging from pure GaP to B0.045Ga0.955P has thus far been achieved. Slightly tensile-strained B0.031Ga0.969P grown on nearly pseudomorphic, compressively strained GaP/Si was used to produce an effectively strain-free (0.06% tensile misfit at growth temperature) 160 nm total III–V thickness BxGa1−xP/Si virtual substrate with a threading dislocation density of &amp;lt;3 × 105 cm−2, at least 4× lower than comparable GaP/Si control samples. Cross-sectional transmission electron microscopy reveals that subsequent GaP overgrowth undergoes epilayer relaxation via dislocation introduction and glide at the upper GaP/B0.031Ga0.969P interface, rather than the lower GaP/Si interface, confirming the strain-balanced nature of the B0.031Ga0.969P/GaP/Si structure and its potential use as a III–V virtual substrate.

High performance waveguide uni-travelling carrier photodiode grown by solid source molecular beam epitaxy.

The first waveguide coupled phosphide-based UTC photodiodes grown by Solid Source Molecular Beam Epitaxy (SSMBE) are reported in this paper. Metal Organic Vapour Phase Epitaxy (MOVPE) and Gas Source MBE (GSMBE) have long been the predominant growth techniques for the production of high quality InGaAsP materials. The use of SSMBE overcomes the major issue associated with the unintentional diffusion of zinc in MOVPE and gives the benefit of the superior control provided by MBE growth techniques without the costs and the risks of handling toxic gases of GSMBE. The UTC epitaxial structure contains a 300 nm n-InP collection layer and a 300 nm n++-InGaAsP waveguide layer. UTC-PDs integrated with Coplanar Waveguides (CPW) exhibit 3 dB bandwidth greater than 65 GHz and output RF power of 1.1 dBm at 100 GHz. We also demonstrate accurate prediction of the absolute level of power radiated by our antenna integrated UTCs, between 200 GHz and 260 GHz, using 3d full-wave modelling and taking the UTC-to-antenna impedance match into account. Further, we present the first optical 3d full-wave modelling of waveguide UTCs, which provides a detailed insight into the coupling between a lensed optical fibre and the UTC chip.

Influence of Growth Temperature of the Nucleation Layer on the Growth of InP on Si (001)

InP layers grown on Si (001) were achieved by the two-step growth method using gas source molecular beam epitaxy. The effects of growth temperature of nucleation layer on InP/Si epitaxial growth were investigated systematically. Cross-section morphology, surface morphology and crystal quality were characterized by scanning electron microscope images, atomic force microscopy images, high-resolution X-ray diffraction (XRD), rocking curves and reciprocal space maps. The InP/Si interface and surface became smoother and the XRD peak intensity was stronger with the nucleation layer grown at 350 °C. The Results show that the growth temperature of InP nucleation layer can significantly affect the growth process of InP film, and the optimal temperature of InP nucleation layer is required to realize a high-quality wafer-level InP layers on Si (001).