Showing papers in "Semiconductor Science and Technology in 2017"
TL;DR: The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored and advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are outlined.
Abstract: The field of visible light communications (VLC) has gained significant interest over the last decade, in both fibre and free-space embodiments. In fibre systems, the availability of low cost plastic optical fibre (POF) that is compatible with visible data communications has been a key enabler. In free-space applications, the availability of hundreds of THz of the unregulated spectrum makes VLC attractive for wireless communications. This paper provides an overview of the recent developments in VLC systems based on gallium nitride (GaN) light-emitting diodes (LEDs), covering aspects from sources to systems. The state-of-the-art technology enabling bandwidth of GaN LEDs in the range of >400 MHz is explored. Furthermore, advances in key technologies, including advanced modulation, equalisation, and multiplexing that have enabled free-space VLC data rates beyond 10 Gb/s are also outlined.
208 citations
TL;DR: In this article, a thin-film type β-Ga2O3/ZnO heterojunction was constructed for the first time by radio frequency magnetron sputtering of a β-O3 layer on a (0001) ZnO single crystalline substrate.
Abstract: A thin-film type β-Ga2O3/ZnO heterojunction was constructed for the first time by radio frequency magnetron sputtering of a β-Ga2O3 layer on a (0001) ZnO single crystalline substrate. The heterojunction presents a typical positive rectification in the dark, and shows a solar-blind deep ultraviolet photoelectric characteristic. Under zero bias, the photodetector based on a β-Ga2O3/ZnO heterojunction exhibits an I photo/I dark ratio of ~14.8 under a 254 nm light illumination with a light intensity of 50 μW cm−2, showing a characteristic of working with zero power consumption. The photocurrent linear increases and the response time decreases with the increase of the light intensity. The photodetector shows a R λ of 0.35 A W−1 and an EQE of 1.7 × 102% under 254 nm illumination of 50 μW cm−2 and a negative bias of 5 V. This study presents a promising candidate for use in solar-blind deep ultraviolet photodetection.
113 citations
TL;DR: In this paper, the authors summarized the advances in research of ALD of titanium dioxide starting from the chemistries of the over 50 different deposition routes developed for TiO2 and the resultant structural characteristics of the films.
Abstract: Within its rich phase diagram titanium dioxide is a truly multifunctional material with a property palette that has been shown to span from dielectric to transparent-conducting characteristics, in addition to the well-known catalytic properties. At the same time down-scaling of microelectronic devices has led to an explosive growth in research on atomic layer deposition (ALD) of a wide variety of frontier thin-film materials, among which TiO2 is one of the most popular ones. In this topical review we summarize the advances in research of ALD of titanium dioxide starting from the chemistries of the over 50 different deposition routes developed for TiO2 and the resultant structural characteristics of the films. We then continue with the doped ALD-TiO2 thin films from the perspective of dielectric, transparent-conductor and photocatalytic applications. Moreover, in order to cover the latest trends in the research field, both the variously constructed TiO2 nanostructures enabled by ALD and the Ti-based hybrid inorganic-organic films grown by the emerging ALD/MLD (combined atomic/molecular layer deposition) technique are discussed. CONTENTS
113 citations
TL;DR: In this paper, a wearable self-powered active sensor for respiration and healthcare monitoring was fabricated based on a flexible piezoelectric nanogenerator and its electrical property was measured.
Abstract: A wearable self-powered active sensor for respiration and healthcare monitoring was fabricated based on a flexible piezoelectric nanogenerator. An electrospinning poly(vinylidene fluoride) thin film on silicone substrate was polarized to fabricate the flexible nanogenerator and its electrical property was measured. When periodically stretched by a linear motor, the flexible piezoelectric nanogenerator generated an output open-circuit voltage and short-circuit current of up to 1.5 V and 400 nA, respectively. Through integration with an elastic bandage, a wearable self-powered sensor was fabricated and used to monitor human respiration, subtle muscle movement, and voice recognition. As respiration proceeded, the electrical output signals of the sensor corresponded to the signals measured by a physiological signal recording system with good reliability and feasibility. This self-powered, wearable active sensor has significant potential for applications in pulmonary function evaluation, respiratory monitoring, and detection of gesture and vocal cord vibration for the personal healthcare monitoring of disabled or paralyzed patients.
104 citations
100 citations
TL;DR: The RFET basics and current status are reviewed and the state of the art of reconfigurable devices will be summarized and the RFET will be introduced together with related devices based on silicon nanowire technology.
Abstract: With CMOS scaling reaching the limits in the next decade, new approaches are required to enhance the functionality of electronic systems. Reconfigurability on the device level promises to realize more complex systems with a lower device count. In the last 5 years a number of interesting concepts have been proposed to realize such a device level reconfiguration. Among these the reconfigurable field effect transistor (RFET), a device that can be configured between an n-channel and p-channel behavior by applying an electrical signal, can be considered as an end of roadmap extension of current technology with only small modifications to the process flow [1]. This paper gives a review on the RFET basics and current status. In the first sections the state of the art of reconfigurable devices will be summarized [2] and the RFET will be introduced together with related devices based on silicon nanowire technology [3]. The device optimization with respect to device symmetry and performance will be discussed next [4,5]. The potential of the RFET device technology will then be shown by discussiing circuit implementations making use of the unique advantages of this device concept [6,7,8]. The basic device concept was also extended towards applications in flexible devices and sensors [9,10] extending the capabilities also towards so called More than Moore applications were new functionalities are implemented in CMOS base processes. Finally the prospects of the RFET device technology will be discussed.
97 citations
66 citations
TL;DR: In this paper, two approaches have been compared for the low temperature epitaxy of thick, partially relaxed GeSn layers on top of Ge strain relaxed buffers, and the benefit of using step-graded instead of constant composition layers when targeting really high Sn contents (16%, here) was conclusively demonstrated.
Abstract: Two approaches have been compared for the low temperature epitaxy of thick, partially relaxed GeSn layers on top of Ge strain relaxed buffers. The benefit of using step-graded instead of constant composition layers when targeting really high Sn contents (16%, here) was conclusively demonstrated. Digermane (Ge2H6) and tin-tetrachloride (SnCl4) were used as Ge and Sn precursors, respectively. The growth pressure (100 Torr) and the F(Ge2H6)/F(SnCl4) mass-flow ratio being constant, it was through a temperature lowering that the Sn concentration in the graded structure was increased. X-ray diffraction, atomic force microscopy and transmission electron microscopy were used to gain access to the Sn concentration, the strain state, the surface morphology and thicknesses of the heterostructures. Using a step-graded approach allowed us to gradually relax the strain in the GeSn layers. It helped us obtain high crystalline quality and avoid Sn segregation/precipitation for high Sn contents.
58 citations
58 citations
TL;DR: In this article, structural, electronic, optical and thermoelectric properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites as a function of X cations belonging to the group IIA were investigated.
Abstract: We report the structural, electronic, optical and thermoelectric (TE) properties of X3PbO (X = Ca, Sr, Ba) anti-perovskites as a function of X cations belonging to the group IIA. The computations are done by using the most recently introduced modified Becke–Johnson potential. It has been observed that the cubic lattice constant increases as the cations change from Ca to Ba, consequently, the bulk modulus reduces. The bottom of conduction band shows strong hybridization between Pb-6p, O-2p and X-s states, in contrast, valence band maxima are mainly manufactured by Pb-6p states. The anti-perovskites exhibit narrow direct band gap that show an inverse relation to the static real dielectric constants that verifies Penn's model. In addition, the X cations induced tuning of the absorption edge in the visible and the ultraviolet energy suggest optical device applications. The computed TE parameters have been found sensitive to the X cations and have been demonstrated to be best suited for the TE devices operating at high temperatures.
58 citations
TL;DR: In this paper, the authors summarized the progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects, and presented their outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein.
Abstract: Over the last decade, there has been increasing interest in transferring the research advances in radiofrequency (RF) rectifiers, the quintessential element of the chip in the RF identification (RFID) tags, obtained on rigid substrates onto plastic (flexible) substrates. The growing demand for flexible RFID tags, wireless communications applications and wireless energy harvesting systems that can be produced at a low-cost is a key driver for this technology push. In this topical review, we summarise recent progress and status of flexible RF diodes and rectifying circuits, with specific focus on materials and device processing aspects. To this end, different families of materials (e.g. flexible silicon, metal oxides, organic and carbon nanomaterials), manufacturing processes (e.g. vacuum and solution processing) and device architectures (diodes and transistors) are compared. Although emphasis is placed on performance, functionality, mechanical flexibility and operating stability, the various bottlenecks associated with each technology are also addressed. Finally, we present our outlook on the commercialisation potential and on the positioning of each material class in the RF electronics landscape based on the findings summarised herein. It is beyond doubt that the field of flexible high and ultra-high frequency rectifiers and electronics as a whole will continue to be an active area of research over the coming years.
TL;DR: A hierarchy of numerical models exist for tunnel-FETs covering a wide range of predictive capabilities and computational complexities as mentioned in this paper, with a possible guidance to the wide and rapidly developing literature in this exciting research field.
Abstract: The research field on tunnel-FETs (TFETs) has been rapidly developing in the last ten years, driven by the quest for a new electronic switch operating at a supply voltage well below 1 V and thus delivering substantial improvements in the energy efficiency of integrated circuits. This paper reviews several aspects related to physics based modeling in TFETs, and shows how the description of these transistors implies a remarkable innovation and poses new challenges compared to conventional MOSFETs. A hierarchy of numerical models exist for TFETs covering a wide range of predictive capabilities and computational complexities. We start by reviewing seminal contributions on direct and indirect band-to-band tunneling (BTBT) modeling in semiconductors, from which most TCAD models have been actually derived. Then we move to the features and limitations of TCAD models themselves and to the discussion of what we define non-self-consistent quantum models, where BTBT is computed with rigorous quantum-mechanical models starting from frozen potential profiles and closed-boundary Schrodinger equation problems. We will then address models that solve the open-boundary Schrodinger equation problem, based either on the non-equilibrium Green's function NEGF or on the quantum-transmitting-boundary formalism, and show how the computational burden of these models may vary in a wide range depending on the Hamiltonian employed in the calculations. A specific section is devoted to TFETs based on 2D crystals and van der Waals hetero-structures. The main goal of this paper is to provide the reader with an introduction to the most important physics based models for TFETs, and with a possible guidance to the wide and rapidly developing literature in this exciting research field.
TL;DR: In this article, the authors investigated the time evolution of GaSe oxidation from monolayer to bulk using Raman spectroscopy, photoluminescence emission, and x-ray photoelectron spectrographs.
Abstract: Two-dimensional (2D) van derWaals semiconductors have been the subject of intense research due to their low dimensionality and tunable optoelectronic properties. However, the stability of these materials in air is one of the important issues that needs to be clarified, especially for technological applications. Here the time evolution of GaSe oxidation from monolayer to bulk is investigated by Raman spectroscopy, photoluminescence emission, and x-ray photoelectron spectroscopy. The Raman spectroscopy study reveals that GaSe monolayers become oxidized almost immediately after exposure to air. However, the oxidation is a self-limiting process taking roughly 5 h to penetrate up to 3 layers of GaSe. After oxidation, GaSe single-layers decompose into amorphous Se which has a strong Raman cross section under red excitation. The present study provides a clear picture of the stability of GaSe in air and will guide future research of GaSe from single- to few-layers for the appropriate development of novel technological applications for this promising 2D material.
TL;DR: In this paper, a review of the physics and applications of mechanical resonators fabricated using GaAs-based heterostructures is presented, as well as those of other groups.
Abstract: Micro/nanomechanical resonators have been extensively studied both for device applications, such as high-performance sensors and high-frequency devices, and for fundamental science, such as quantum physics in macroscopic objects. The advantages of GaAs-based semiconductor heterostructures include improved mechanical properties through strain engineering, highly controllable piezoelectric transduction, carrier-mediated optomechanical coupling, and hybridization with quantum low-dimensional structures. This article reviews our recent activities, as well as those of other groups, on the physics and applications of mechanical resonators fabricated using GaAs-based heterostructures.
TL;DR: In this paper, the photonic properties of GaAs-AlGaAs core-shell nanowire (NW) waveguides are investigated under various optical pumping schemes ranging from pulsed to continuous wave excitation.
Abstract: Semiconductor nanowire (NW) lasers provide significant potential to create a new generation of lasers and on-chip coherent light sources by virtue of their ability to operate as single mode optical waveguides at the nanoscale. Due to their unique geometry, a major benefit lies also in the feasibility for direct integration on silicon (Si), enabling III–V-on-Si NW lasers that could fuel applications in optical interconnects and data communication. In this review, we describe the state-of-the-art and recent progress in GaAs–AlGaAs based NW lasers emitting in the near infrared (NIR) spectral region, with a specific emphasis on integration on a Si platform. First, we explore design rules for the photonic properties in GaAs NW waveguides based on finite difference time domain calculations. The lasing characteristics of GaAs–AlGaAs core–shell NW lasers are then investigated under various different optical pumping schemes ranging from pulsed to continuous wave excitation. We further review recent activities on the realization of low-dimensional quantum heterostructures inside NW cavities as a means to tune lasing wavelength, gain and threshold properties. Ultimately, we describe schemes for monolithic integration of GaAs-based NW lasers directly on Si and show how such vertical nanocavity lasers are excellent candidates for low-threshold lasing, high spontaneous emission coupling (high β-factor lasers), and ultrafast emission characteristics.
TL;DR: In this article, the application of nanostructures for light management to chalcopyrite (CIGSe) type solar cells is reviewed and applicable concepts of nanometrics for absorption enhancement discussed.
Abstract: Light management has gained wide interest for various types of solar cells. This paper reviews the application of nanostructures for light management to chalcopyrite (CIGSe) type solar cells. Firstly, the relevance of light management for CIGSe solar cells will be introduced and applicable concepts of nanostructures for absorption enhancement discussed. The development of ultra-thin CIGSe solar cells and examples for nanoparticle fabrication techniques together with their chances and challenges for application to CIGSe will be presented. Particular attention will be paid to nanostructures that have been applied to CIGSe solar cells, revealing many theoretical and some experimental results. Metallic and dielectric nanostructures as well as intrinsic nanotextures will be covered. For the future, combined considerations of optical and electrical properties will gain in importance.
TL;DR: In this paper, a review of recent progress in the characterization, properties evaluation and applications of 2D piezoelectric nanomaterials (PNs) is presented, which can open the doors to the innovative design of next generation nanoelectronics and nanodevices.
Abstract: The discovery of piezoelectricity in two-dimensional (2D) nanomaterials represents a milestone towards embedding the low-dimensional materials into future technologies. This paper reviews recent progress in the characterization, properties evaluation and applications of piezoelectricity of 2D piezoelectric nanomaterials (PNs). To begin, an introduction to the existing 2D PNs which exhibit a wide range of atomic structures and configurations is presented. The nanoscale measurements and the associated experimental techniques as well as the atomic simulations of the piezoelectric properties of 2D PNs are then summarised. Some of the pertinent parameters which govern the piezoelectric properties of 2D PNs are discussed. Furthermore, our paper concludes with some potential applications including piezotronics, piezophototronics and energy harvesting of 2D PNs, which can open the doors to the innovative design of next-generation nanoelectronics and nanodevices. Finally, perspectives and challenges for the future development of 2D PNs are pointed out.
TL;DR: In this paper, the optoelectronic properties of few-layered MoSe2-based back-gated phototransistors used for photodetection were reported.
Abstract: In recent years, the integration of two-dimensional (2D) nanomaterials, especially transition metal chalcogendies (TMCs) and dichalcogendies (TMDCs), into electronic devices have been extensively studied owing to their exceptional physical properties such as high transparency, strong photoluminescence, and tunable bandgap depending on the number of layers Herein, we report the optoelectronic properties of few-layered MoSe2-based back-gated phototransistors used for photodetection The photoresponsivity could be easily controlled to reach a maximum value of 238 AW−1 under near-infrared light excitation, achieving a high specific detectivity Few-layered MoSe2 exhibited excellent optoelectronic properties compared with those reported previously for multilayered 2D material-based photodetectors, indicating that our device is one of the best high-performance nanoscale near-infrared photodetectors based on multilayered two-dimensional materials
TL;DR: In this article, the persistent spin helix (PSH) state is considered and the conditions of a PSH state in semiconductor heterostructures are discussed, as well as the application of PSH states for spin transistors and logic circuits.
Abstract: In order to utilize the spin degree of freedom in semiconductors, control of spin states and transfer of the spin information are fundamental requirements for future spintronic devices and quantum computing. Spin orbit (SO) interaction generates an effective magnetic field for moving electrons and enables spin generation, spin manipulation and spin detection without using external magnetic field and magnetic materials. However, spin relaxation also takes place due to a momentum dependent SO-induced effective magnetic field. As a result, SO interaction is considered as a double-edged sword facilitating spin control but preventing spin transport over long distances. The persistent spin helix (PSH) state solves this problem since uniaxial alignment of the SO field with SU(2) symmetry enables the suppression of spin relaxation while spin precession can still be controlled. Consequently, understanding the PSH becomes an important step towards future spintronic technologies for classical and quantum applications. Here, we review recent progress of PSH in semiconductor heterostructures and its device application. Fundamental physics of SO interaction and the conditions of a PSH state in semiconductor heterostructures are discussed. We introduce experimental techniques to observe a PSH and explain both optical and electrical measurements for detecting a long spin relaxation time and the formation of a helical spin texture. After emphasizing the bulk Dresselhaus SO coefficient, the application of PSH states for spin transistors and logic circuits are discussed.
TL;DR: In this paper, the authors used piezoelectric Zinc Oxide (ZnO) nanogenerators (NGs) for low frequency (<100 Hz) energy harvesting applications.
Abstract: Piezoelectric Zinc Oxide (ZnO) nanogenerators (NGs) have been fabricated for low frequency (<100 Hz) energy harvesting applications. Different types of NGs based on ZnO nanostructures have been carefully developed, and studied for testing under different kinds of low frequency mechanical deformations. Well aligned ZnO nanowires (NWs) possessing high piezoelectric coefficient were synthesized on flexible substrates using the low temperature hydrothermal route. These ZnO NWs were then used in different configurations to demonstrate different low frequency energy harvesting devices. Using piezoelectric ZnO NWs, we started with the fabrication of a sandwiched NG for a handwriting enabled energy harvesting device based on a thin silver layer coated paper substrate. Such device configurations can be used for the development of electronic programmable smart paper. Further, we developed this NG to work as a triggered sensor for a wireless system using footstep pressure. These studies demonstrate the feasibility of using a ZnO NWs piezoelectric NG as a low-frequency self- powered sensor, with potential applications in wireless sensor networks. After that, we investigated and fabricated a sensor on a PEDOT: PSS plastic substrate using a one-sided growth and double-sided growth technique. For the first growth technique, the fabricated NG has been used as a sensor for an acceleration system; while the fabricated NG by the second technique works as an anisotropic direction sensor. This fabricated configuration showed stability for sensing and can be used in surveillance, security, and auto-Mobil applications. In addition to that, we investigated the fabrication of a sandwiched NG on plastic substrates. Finally, we demonstrated that doping ZnO NWs with extrinsic elements (such as Ag) will lead to the reduction of the piezoelectric effect due to the loss of crystal symmetry. A brief summary into future opportunities and challenges is also presented.
TL;DR: In this paper, the Schottky barrier height and ideality factor were estimated by currentvoltage (I-V) measurements performed at temperatures varying from 300 K to 500 K on the Sn-doped β-Ga2O3 (010) diodes.
Abstract: Coherent β-(AlxGa1−x)2O3 films (x = 0, 0.038, 0.084, 0.164) were grown successfully on a Sn-doped β-Ga2O3 (010) substrate using plasma-assisted molecular beam epitaxy. Atom probe tomography, transmission electron microscopy, and high resolution x-ray diffraction were used to verify the alloy composition and high quality of the films. Schottky diodes were then fabricated using Ni as the Schottky metal. Capacitance–voltage measurements revealed a very low (<7 × 1015 cm−3) free charge density in the nominally undoped films. The barrier height and ideality factor were estimated by current–voltage (I–V) measurements performed at temperatures varying from 300 K to 500 K on the Schottky diodes. These measurements revealed that the apparent Schottky barrier height could have similar values for different compositions of β-(AlxGa1−x)2O3. We believe this is attributed to the lateral fluctuation in the alloy's composition. This results in a lateral variation in the barrier height. Therefore, the average Schottky barrier height extracted from I–V measurements could be similar for β-(AlxGa1−x)2O3 films with different compositions.
TL;DR: In this article, the structural stability of Co2TaZ alloys is forecast on the basis of total energy calculations and mechanical stability criteria. And the observed structural aspects calculated to predict the stability and equilibrium lattice parameters agree well with the experimental results.
Abstract: Ferromagnetic Heusler compounds have vast and imminent applications for novel devices, smart materials thanks to density functional theory (DFT) based simulations, which have scored out a new approach to study these materials. We forecast the structural stability of Co2TaZ alloys on the basis of total energy calculations and mechanical stability criteria. The elastic constants, robust spin-polarized ferromagnetism and electron densities in these half-metallic alloys are also discussed. The observed structural aspects calculated to predict the stability and equilibrium lattice parameters agree well with the experimental results. The elastic parameters like elastic constants, bulk, Young's and shear moduli, poison's and Pugh ratios, melting temperatures, etc have been put together to establish their mechanical properties. The elaborated electronic band structures along with indirect band gaps and spin polarization favour the application of these materials in spintronics and memory device technology.
TL;DR: In this article, a flexible thermoelectric nanogenerator (NG) based on the MoS2/graphene nanocomposite was proposed. But the authors did not consider the performance of the NG as a self-powered sensor for temperature measurement.
Abstract: In this work, we report on a flexible thermoelectric nanogenerator (NG) based on the MoS2/graphene nanocomposite. The nanocomposite thermoelectric nanogenerator shows enhanced thermoelectric performance, compared with that based solely on MoS2 nanomaterials, which may be due to the enhanced electrical conductivity resulting from the graphene acting as a charge transfer channel in the composites. The NG can be further applied as a self-powered sensor for temperature measurement. This work indicates that the MoS2/graphene nanocomposite is a promising thermoelectric material for harvesting environmental thermal energy.
TL;DR: In this paper, the physics and performance of various advanced semiconductor devices, which are the most promising for the end of the ITRS roadmap, are investigated in a wide temperature range down to 20 K.
Abstract: The physics and performance of various advanced semiconductor devices, which are the most promising for the end of the ITRS roadmap, are investigated in a wide temperature range down to 20 K. The transport parameters in front and/or back channels in fully depleted ultrathin film SOI devices, Trigate, FinFET, Omega-gate nanowire FET and 3D-stacked SiGe nanowire FETs, fabricated with high-k dielectrics/metal gate, elevated source/drain, different channel orientations, shapes and strains, are addressed. The impacts of the gate length, Si film and wire diameter down to 10 nm, are also shown. The variations of the phonon, Coulomb, neutral defects and surface roughness scattering as a function of temperature and device architecture are highlighted. An overview of the influence of temperature on other main electrical parameters of MOSFETs, nanowires FETs and tunnel FETs, such as threshold voltage, subthreshold swing, leakage and driving currents is also given.
TL;DR: 3 × 3 crossbar arrays of titanium oxide were fabricated and tested for non-volatile memory applications and neuromorphic pattern recognition and all three input patterns were recognized.
Abstract: In this work 3 × 3 crossbar arrays of titanium oxide were fabricated and tested for non-volatile memory applications and neuromorphic pattern recognition The non-volatile memory characteristics of the memristor were examined using retention tests for each memristor In order to test neuromorphic pattern recognition, the memristor crossbar array was programmed to store '111', '100' and '010' at the first, second and third columns of the array, where '0' and '1' represent the high-resistance state (HRS) and low-resistance state (LRS), respectively The three similar input patterns of '111', '100' and '010' were applied to the crossbar array, for pattern recognition Using a twin memristor crossbar array mechanism all three input patterns were recognized
Journal Article•
TL;DR: In this article, the plastic strain relaxation of CVD-grown Ge1−x Sn x layers was investigated in x = 0.09 samples with thicknesses of 152, 180, 257, 570, and 865 nm.
Abstract: The plastic strain relaxation of CVD-grown Ge1−x Sn x layers was investigated in x = 0.09 samples with thicknesses of 152, 180, 257, 570, and 865 nm. X-ray diffraction-reciprocal space mapping was used to determine the strain, composition, and the nature of defects in each layer. Secondary ion mass spectrometry was used to examine the evolution of the compositional profile. These results indicate that growth beyond the critical thickness results in the spontaneous formation of a relaxed and highly defective 9% Sn layer followed by a low defect 12% Sn secondary layer. We find that this growth method can be used to engineer thick, strain-relaxed, and low defect density layers. Furthermore we utilize this strain-dependent Sn incorporation behavior to achieve Sn compositions of 17.5%. Photoluminesence of these layers produces light emission at 3.1 μm.