InSb has the smallest bandgap and highest electron mobility among III‐V semiconductors and is widely used for photodetectors and high‐frequency electronic applications. Integration of InSb directly on Si would drastically reduce the fabrication cost and enable new applications, however, it is very challenging due to its 19% lattice mismatch with Si. Herein, the integration of single‐crystalline InSb microstructures on insulator‐covered Si through rapid melt growth (RMG) is reported and specifically provides details on the fabrication process. The importance of achieving high‐quality conformal capping layers at low thermal budget to contain the InSb melt is assessed when the sample is annealed. The importance of ensuring a pristine Si seed area to achieve single‐crystalline InSb is illustrated and demonstrated here for the first time.

Interactions between excitons with different energies are significant in device application, particularly in the emission of intense terahertz (THz) waves caused by difference frequency mixing. In this paper, the interactions of excitons generated by two resonant continuous-wave laser beams are assessed via the change in reflectivity. While calculations suggest that the reflectivity change depends on the exciton number, experimental results measured for various excitation powers, probe powers, and excitation energies (heavy-hole (HH) and light-hole (LH) excitons) show different profiles. Furthermore, the signals probed at a HH exciton differ from those at a LH exciton. These results indicate the importance of careful control of excitation levels for THz wave generation.

Intense terahertz-wave emission in the higher frequency region can result in various applications such as terahertz spectroscopy and ultrafast data communication. In this study, an increase in terahertz waves by the overlap of exciton states in different quantum wells and spectroscopic demonstration are reported. The excitation energy dependence of signal intensity shows the effect of the overlap. The signals measured under the condition of square dependence of intensity on the excitation power indicate interference with the periods corresponding to the laser energy difference. Furthermore, the absorption coefficient of the transparent sheet is obtained at specific frequency. These results indicate that the generation of intense terahertz waves at various frequencies using excitons is possible and that difference frequency mixing is a useful terahertz-wave source.

In single microdisks, embedded active emitters intrinsically affect the cavity modes of the microdisks, resulting in trivial symmetric backscattering and low controllability. Here we demonstrate macroscopic control of the backscattering direction by optimizing the cavity size. The signature of the positive and negative backscattering directions in each single microdisk is confirmed with two strongly coupled microdisks. Furthermore, diabolical points are achieved at the resonance of the two microdisks, which agrees well with theoretical calculations considering the backscattering directions. Diabolical points in active optical structures pave the way for an implementation of quantum information processing with geometric phase in quantum photonic networks.

The stability of excitons with large oscillator strengths at room temperature has been of great significance in device applications. In this paper, we report the effects of the ultrafast dissociation of excitons confined in a quantum well on optical characteristics. The photoluminescence spectra show components of higher energy than the excitation energy and a nonlinear increment of the intensity. Furthermore, the spectrally resolved pump–probe signals at the exciton energies elucidate the change in the exciton position. These results indicate the importance of the exciton stability in optical devices, in particular emission type, including terahertz wave, based on excitons.

We present indium antimonide-based devices for mid-infrared (mid-IR) detection with enhanced sensitivity. InSb devices will be useful for many applications, such as gas sensing and imaging. InSb avalanche photodiodes (APDs) monolithically integrated with GaAs substrates were fabricated with diameters ranging from 90 to $200\mu \text{m}$ and extensively characterized at temperatures ranging from 77 K to 300 K. At 120 K a zero-bias responsivity of 2 A/W was measured, corresponding to a quantum efficiency of 55. An experimental gain value of 10 at a reverse bias of -3 V was obtained at 120 K, which to the best of our knowledge, is the highest ever reported for InSb APDs. These results pave the way for the development of a monolithically integrated mid-IR array with added gain and wavelength tunability.

Monolithic integration of III-V semiconductors with Silicon technology has instigated a wide range of new possibilities in the semiconductor industry, such as combination of digital circuits with optical sensing and high-frequency communication. A promising CMOS compatible integration process is rapid melt growth (RMG) that can yield high quality single crystalline material at low cost. This paper represents the study on ultra-thin InSb-on-insulator microstructures integrated on a Si platform by a RMG-like process. We utilize flash lamp annealing (FLA) to melt and recrystallize the InSb material for an ultra-short duration (milliseconds), to reduce the thermal budget necessary for integration with Si technology. We compare the result from FLA to regular rapid thermal annealing (seconds). Recrystallized InSb was characterized using electron back scatter diffraction which indicate a transition from nanocrystalline structure to a crystal structure with grain sizes exceeding 1 μm after the process. We further see a 100× improvement in electrical resistivity by FLA annealed sample when compared to the as-deposited InSb with an average Hall mobility of 3100 cm2 V-1 s-1 making this a promising step towards realizing monolithic mid-infrared detectors and quantum devices based on InSb.

The results of an investigation into the impact of in situ H-2 plasma exposure on the electrical properties of the p/n-In-0.3 Ga-0.7 Sb-Al2O3 interface are presented. Samples were processed using a clustered inductively coupled plasma reactive ion etching and atomic layer deposition tool. Metal oxide semiconductor capacitors were fabricated subsequent to H-2 plasma processing and Al2O3 deposition, and the corresponding capacitance-voltage and conductance-voltage measurements were analyzed quantitatively via the simulation of an equivalent circuit model. Interface state (D-it) and border trap (N-bt) densities were extracted for samples subjected to the optimal process, with a minimum D-it of 1.73 x 10(12) eV(-1) cm(-2) located at similar to 110meV below the conduction band edge and peak N-bt approximately aligned with the valence and conduction band edges of 3 x 10(19) cm(-3) and 6.5 x 10(19) cm(-3), respectively. Analysis of the inversion response in terms of the extraction of the activation energy of minority carriers in inversion (p-type) and the observation of characteristics that pertain to minority carriers being supplied from an external inversion region (n-type) unequivocally demonstrate that the Fermi level is unpinned and that genuine surface inversion is observed for both doping polarities. Published under license by AIP Publishing.

Monolithic integration of III-V semiconductors with Silicon technology has instigated a wide range of new possibilities in the semiconductor industry, such as combination of digital circuits with optical sensing and high-frequency communication. Dissimilarities in the crystal structure symmetry and large lattice mismatch between III-V’s and Si are the challenges that prevent direct epitaxial growth of III-V on Si. A promising method is Rapid Melt Growth (RMG) which integrates high-quality single crystalline III-V microstructures at low cost and in a process that is CMOS compatible1. In this growth, amorphous source material is deposited inside a micro-crucible with a nano-scale opening (seed) to the Si substrate. When the material is annealed above its melting point, the crucible contains the liquid. On cooling, epitaxial growth occurs from the seed to the end of the structure, resulting in a high quality crystal as strain-induced misfit dislocations are confined to the region near the seed. RMG of Ge on insulator [1], GaAs2, GaSb2 and InAs3 has been reported. In this work we have developed for the first time the RMG process for integrating InSb nano and microstructures on Si. Such InSb materials are promising for integrated optoelectronics (mid-infrared) and topological quantum devices. We will here describe the process development and characterization of the resulting InSb material using x-ray diffraction, electron backscatter diffraction, atomic force microscopy, and electrical measurements. 1. Liu et al. APL. 84, 2563 (2004).2. Chen et al. Electron Dev Lett. 31, 11 (2010).3. Yuan et al. Symp VLSI Tech Dig. T54-5 (2013) (Less)

Large coupling strengths in exciton-photon interactions are important for the quantum photonic network, while strong cavity-quantum dot interactions have been focused on s-shell excitons with small coupling strengths. Here we demonstrate strong interactions between cavities and p-shell excitons with a great enhancement by the in situ wave-function control. The p-shell excitons are demonstrated with much larger wave-function extents and nonlocal interactions beyond the dipole approximation. Then the interaction is tuned from the nonlocal to the local regime by the wave function shrinking, during which the enhancement is obtained. A large coupling strength of 210  μeV has been achieved, indicating the great potential of p-shell excitons for coherent information exchange. Furthermore, we propose a distributed delay model to quantitatively explain the coupling strength variation, revealing the intertwining of excitons and photons beyond the dipole approximation.

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We discuss a novel approach to the optimisation of quantum dot bilayer structures grown by molecular beam epitaxy. It has been observed that vertically stacked quantum dot structures often exhibit an increase in the average size of the islands with increasing number of quantum dot layers deposited. The understanding of the In segregation induced Stranski-Krastanow transition suggests that this is due to excess of In caused by elemental segregation. In order to limit the non uniformity of the sizes along the stacks we have grown the upper layers with different concentrations of In, showing that the optimum fraction is the one predicted by the kinetic segregation model.

Two-photon Rabi splitting in a cavity-dot system provides a basis for multiqubit coherent control in a quantum photonic network. Here we report on two-photon Rabi splitting in a strongly coupled cavity-dot system. The quantum dot was grown intentionally large in size for a large oscillation strength and small biexciton binding energy. Both exciton and biexciton transitions couple to a high-quality-factor photonic crystal cavity with large coupling strengths over 130  μeV. Furthermore, the small binding energy enables the cavity to simultaneously couple with two exciton states. Thereby, two-photon Rabi splitting between the biexciton and cavity is achieved, which can be well reproduced by theoretical calculations with quantum master equations.

In recent years there has been a rapidly increasing demand for energy-efficient and cost effective gas sensors. Of particular interest are CO2 sensors that can find numerous applications in health monitoring, control of air quality and horticulture. A major hurdle comes from the fact that the main CO2 absorption band lies above 4um, where very few cheap and compact sources are commercially available. Amongst the various approaches explored, the indium antimonide material system stands out as a very effective solution for the development of compact Light Emitting Diodes (LEDs). In particular, the quaternary compound AlGaInSb shows great promise as it offers a bandgap type-I alignment, which enables the design of effective multi-quantum well (MQW) active regions. In this paper we show the great potential of LED structures with strained GaInSb MQWs and AlGaInSb barriers for the next generation of mid-IR emitters at 4.3 um. Different quantum well and barrier compositions were examined through k.p simulations to extract momentum matrix elements and energy levels. The simulations were also used to assess the impact of strain and quantum well width on the efficiency of the radiative transition and to optimise the profile of the carrier injection. Based on the theoretical analysis, a number of different epilayer structures were grown by molecular beam epitaxy and the performance of LEDs with varying geometries were compared. Results confirm that strained MQW structures suppress unwanted transitions by at least one order of magnitude and provide a substantial enhancement in the internal quantum efficiency of the LEDs.

In this work, performance improvements are described for a low-power consumption non-dispersive infrared (NDIR) methane (CH4) gas sensor using customised optical thin film bandpass filters (BPFs) centered at 3300 nm. BPFs shape the spectral characteristics of the combined mid-infrared III–V based light emitting diode (LED)/photodiode (PD) light source/detector optopair, enhancing the NDIR CH4 sensor performance. The BPFs, deposited using a novel microwave plasma-assisted pulsed DC sputter deposition process, provide room temperature deposition directly onto the temperature-sensitive PD heterostructure. BPFs comprise germanium (Ge) and niobium pentoxide (Nb2O5) alternating high and low refractive index layers, respectively. Two different optical filter designs are progressed with BPF bandwidths (BWs) of 160 and 300 nm. A comparison of the modelled and measured NDIR sensor performance is described, highlighting the maximised signal-to-noise ratio (SNR) and the minimised cross-talk performance benefits. The BPF spectral stability for various environmental temperature and humidity conditions is demonstrated.

The junctionless MOSFET (JLFET) architecture has attracted much attention as an enabling technology for ultra-scaled CMOS devices [1]. The dominant scattering mechanism in JLFETs is impurity scattering due to its necessarily highly doped channel [1]. Accordingly, III-V's may offer an even greater advantage as the channel material for JLFETs than for conventional MOSFETs as they suffer less from mobility degradation due to impurity scattering [2]. Current Si CMOS devices employ non-planar architectures with high aspect ratio fins which serve to increase the on current (Ion) per chip surface area [3]. This necessitates that any incarnation of a III - V MOSFET must also exploit the vertical dimension. Additionally, it must do so by employing a `top-down' fabrication approach to remain compatible with Si CMOS processing. This requires a low Dit dielectric interface to etched III-V fin sidewalls. To date, all III-V junctionless FinFETs (JLFinFETs) demonstrated have employed fin heights which are smaller than the maximum depletion width of their respective channels, and therefore can be well modulated by the top gate only: offering little insight into the effectiveness of the gated sidewalls. We implement a low damage etch process to form high aspect ratio, In053Ga047As JLFinFETs which have record performance in terms of Ion normalized to fin width.

Journal Article TEM characterization of GaSb grown on single crystal offcut Silicon (001) Get access H L Porter, H L Porter School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK Search for other works by this author on: Oxford Academic Google Scholar M J Steer, M J Steer School of Engineering, University of Glasgow, Glasgow G12 8LT, UK Search for other works by this author on: Oxford Academic Google Scholar A J Craven, A J Craven School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK Search for other works by this author on: Oxford Academic Google Scholar D McGrouther, D McGrouther School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK Search for other works by this author on: Oxford Academic Google Scholar I G Thayne, I G Thayne School of Engineering, University of Glasgow, Glasgow G12 8LT, UK Search for other works by this author on: Oxford Academic Google Scholar I MacLaren I MacLaren School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 23, Issue S1, 1 July 2017, Pages 1476–1477, https://doi.org/10.1017/S1431927617008042 Published: 04 August 2017

The need for energy efficiency and lower emissions from industrial plants and infrastructures is driving research into novel sensor technologies, especially those that allow observing and measuring greenhouse gases, such as CO2. CO2 emissions can be captured using mid-infrared imagers, but at present, these are based on hybrid technologies that need expensive manufacturing and require cooling. The high price tag prevents a wider diffusion of mid-infrared imagers and hence their use for many low-cost and large-volume applications. Here we report a monolithic III-V technology that integrates GaAs transistors with an InSb photodiode array. The monolithic material system reduces costs and provides an excellent platform for the sensor system-on-chip. We present a focal plane array imaging technology operating at room temperature in the 3-6 mu m wavelength range that will address the need for identification and measurement of a range of industrially important gases.