A Comparison of Common Quantum Dot Alternatives to Cadmium-Based Quantum Dots on the Basis of Liver Cytotoxicity.

Fluorescent nanoparticles known as quantum dots (QDs) have unique properties that make them useful in biomedicine. Specifically, CdSe/ZnS QDs, while good at fluorescing, show toxicity. Due to this, safer alternatives have been developed. This study uses a tetrazolium dye (XTT) viability assay, reactive oxygen species (ROS) fluorescent imaging, and apoptosis to investigate the effect of QD alternatives InP/ZnS, CuInS2/ZnS, and nitrogen-doped carbon dots (NCDs) in liver cells. The liver is a possible destination for the accumulation of QDs, making it an appropriate model for testing. A cancerous liver cell line known as HepG2 and an immortalized liver cell line known as THLE-2 were used. At a nanomolar range of 10-150, HepG2 cells demonstrated no reduced cell viability after 24 h. The XTT viability assay demonstrated that CdSe/ZnS and CuInS2/ZnS show reduced cell viability in THLE-2 cells with concentrations between 50 and 150 nM. Furthermore, CdSe/ZnS- and CuInS2/ZnS-treated THLE-2 cells generated ROS as early as 6 h after treatment and elevated apoptosis after 24 h. To further corroborate our results, apoptosis assays revealed an increased percentage of cells in the early stages of apoptosis for CdSe/ZnS-treated (52%) and CuInS2/ZnS-treated (38%) THLE-2. RNA transcriptomics revealed heavy downregulation of cell adhesion pathways such as wnt, cadherin, and integrin in all QDs except NCDs. In conclusion, NCDs show the least toxicity toward these two liver cell lines. While demonstrating less toxicity than CdSe/ZnS, the metallic QDs (InP/ZnS and CuInS2/ZnS) still demonstrate potential concerns in liver cells. This study serves to explore the toxicity of QD alternatives and better understand their cellular interactions.

Transition Layer Assisted Synthesis of Defect Free Amine-Phosphine Based InP QDs.

Environmentally friendly InP-based quantum dots (QDs) are promising for light-emitting diodes (LEDs) and display applications. So far, the synthesis of highly emitting InP-based QDs via safe and economically viable amine-phosphine remains a challenge. Herein, we report the synthesis of amine-phosphine based InP/ZnSe/ZnS QDs by introducing an alloyed oxidation-free In-ZnSe transition layer (TL) at the core-shell interface. The TL not only has the essential function of preventing oxidation of the core and relieving interfacial strain but also results in oriented epitaxial growth of shell. The alloyed TL significantly mitigates the nonradiative recombination at core-shell interfacial trap states, thereby boosting the photoluminescence (PL) efficiency of the QDs up to 98%. Also, the Auger recombination is suppressed, extending the biexciton lifetime from 60 to 100 ps. The electroluminescence device based on the InP-based QDs shows a high external quantum efficiency over 10%, further demonstrating high quality QDs synthesized by this process.

Encapsulation of InP/ZnS Quantum Dots into MOF-5 Matrices for Solid-State Luminescence: Ship in the Bottle and Bottle around the Ship Methodologies.

The utilization of InP-based quantum dots (QDs) as alternative luminescent nanoparticles to cadmium-based QDs is actively pursued. However, leveraging their luminescence for solid-state applications presents challenges due to the sensitivity of InP QDs to oxidation and aggregation-caused quenching. Hence, an appealing strategy is to protect and disperse InP QDs within hybrid materials. Metal-organic frameworks (MOFs) offer a promising solution as readily available crystalline porous materials. Among these, MOF-5 (composed of {Zn4O}6+ nodes and terephthalate struts) can be synthesized under mild conditions (at room temperature and basic pH), making it compatible with InP QDs. In the present work, luminescent InP/ZnS QDs are successfully incorporated within MOF-5 by two distinct methods. In the bottle around the ship (BAS) approach, the MOF was synthesized around the QDs. Alternatively, in the ship in the bottle (SIB) strategy, the QDs were embedded via capillarity into a specially engineered, more porous variant of MOF-5. Comparative analysis of the BAS and SIB approaches, evaluating factors such as operational simplicity, photoluminescence properties, and the resistance of the final materials to leaching were carried out. This comparative study provides insights into the efficacy of these strategies for the integration of InP/ZnS QDs within MOF-5 for potential solid-state applications in materials chemistry.

Cytoplasmic TP53INP2 acts as an apoptosis partner in TRAIL treatment: the synergistic effect of TRAIL with venetoclax in TP53INP2-positive acute myeloid leukemia.

BACKGROUND: Acute myeloid leukemia (AML) is a hematopoietic malignancy with poor outcomes, especially in older AML patients. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered a promising anticancer drug because it selectively induces the extrinsic apoptosis of tumor cells without affecting normal cells. However, clinical trials have shown that the responses of patients to TRAIL are significantly heterogeneous. It is necessary to explore predictable biomarkers for the preselection of AML patients with better responsiveness to TRAIL. Here, we investigated the critical role of tumor protein p53 inducible nuclear protein 2 (TP53INP2) in the AML cell response to TRAIL treatment. METHODS: First, the relationship between TP53INP2 and the sensitivity of AML cells to TRAIL was determined by bioinformatics analysis of Cancer Cell Line Encyclopedia datasets, Cell Counting Kit-8 assays, flow cytometry (FCM) and cell line-derived xenograft (CDX) mouse models. Second, the mechanisms by which TP53INP2 participates in the response to TRAIL were analyzed by Western blot, ubiquitination, coimmunoprecipitation and immunofluorescence assays. Finally, the effect of TRAIL alone or in combination with the BCL-2 inhibitor venetoclax (VEN) on cell survival was explored using colony formation and FCM assays, and the effect on leukemogenesis was further investigated in a patient-derived xenograft (PDX) mouse model. RESULTS: AML cells with high TP53INP2 expression were more sensitive to TRAIL in vitro and in vivo. Gain- and loss-of-function studies demonstrated that TP53INP2 significantly enhanced TRAIL-induced apoptosis, especially in AML cells with nucleophosmin 1 (NPM1) mutations. Mechanistically, cytoplasmic TP53INP2 maintained by mutant NPM1 functions as a scaffold bridging the ubiquitin ligase TRAF6 to caspase-8 (CASP 8), thereby promoting the ubiquitination and activation of the CASP 8 pathway. More importantly, simultaneously stimulating extrinsic and intrinsic apoptosis signaling pathways with TRAIL and VEN showed strong synergistic antileukemic activity in AML cells with high levels of TP53INP2. CONCLUSION: Our findings revealed that TP53INP2 is a predictor of responsiveness to TRAIL treatment and supported a potentially individualized therapeutic strategy for TP53INP2-positive AML patients.

Near-Unity Photoluminescence Quantum Yield of Core-Only InP Quantum Dots via a Simple Postsynthetic InF3 Treatment.

Indium phosphide (InP) quantum dots (QDs) are considered the most promising alternative for Cd and Pb-based QDs for lighting and display applications. However, while core-only QDs of CdSe and CdTe have been prepared with near-unity photoluminescence quantum yield (PLQY), this is not yet achieved for InP QDs. Treatments with HF have been used to boost the PLQY of InP core-only QDs up to 85%. However, HF etches the QDs, causing loss of material and broadening of the optical features. Here, we present a simple postsynthesis HF-free treatment that is based on passivating the surface of the InP QDs with InF3. For optimized conditions, this results in a PLQY as high as 93% and nearly monoexponential photoluminescence decay. Etching of the particle surface is entirely avoided if the treatment is performed under stringent acid-free conditions. We show that this treatment is applicable to InP QDs with various sizes and InP QDs obtained via different synthesis routes. The optical properties of the resulting core-only InP QDs are on par with InP/ZnSe/ZnS core-shell QDs, with significantly higher absorption coefficients in the blue, and with potential for faster charge transport. These are important advantages when considering InP QDs for use in micro-LEDs or photodetectors.

InP Crystal Phase Heterojunction Transistor with a Vertical Gate-All-Around Structure.

Crystal phase transitions can form a new type of heterojunction with different atomic arrangements in the same material: crystal phase heterojunction (CPHJ). The CPHJ has an inherently strong impact on band engineering without concerns over critical thicknesses with misfit dislocations and a semiconductor-metal transition. In-plane CPHJ was recently demonstrated in two-dimensional (2D) transition-metal dichalcogenide (TMD) materials and utilized for conventional planar field-effect transistor applications. However, scalability such as gate electrostatic control, miniaturization, and multigate structure have been limited because of the geometrical issue. Here, we demonstrated a transistor using the CPHJ with a vertical gate-all-around structure by forming a CPHJ in conventional III-V semiconductors. The CPHJ, composed of wurtzite InP nanowires with zincblende InP substrates, showed an atomically flat heterojunction without dislocations and indicated a Type-II band discontinuity across the junction. The CPHJ transistor had moderate to good gate electrostatic controllability with high on-state currents and transconductance. The CPHJ offer will provide a new switching mechanism and add a new junction and device design choice to the long history of transistors.

Cardiovascular safety of dihydroergotamine mesylate delivered by precision olfactory delivery (INP104) for the acute treatment of migraine.

OBJECTIVE: To report the cardiovascular (CV) safety of dihydroergotamine mesylate (DHE) administered by precision olfactory delivery (INP104) from two clinical trials. BACKGROUND: Although the absolute risk is low, migraine is associated with an increased risk of CV events. DHE is a highly effective acute treatment for migraine, but due to its theoretical risk of promoting arterial vasoconstriction, DHE is contraindicated in patients with CV disease or an unfavorable risk factor profile. The INP104 is a novel drug-device combination product approved for acute treatment of migraine that delivers DHE to the upper nasal space using precision olfactory delivery (POD®). METHODS: The STOP 101 was a Phase 1 open-label study that assessed the safety, tolerability, and bioavailability of INP104 1.45 mg, intravenous DHE 1.0 mg, and MIGRANAL (nasal DHE) 2.0 mg in healthy participants. The STOP 301 was a pivotal Phase 3, open-label study that assessed the safety, tolerability, and exploratory efficacy of INP104 1.45 mg over 24 and 52 weeks in patients with migraine. In both studies, active or a history of CV disease, as well as significant CV risk factors, were exclusion criteria. RESULTS: In STOP 101, 36 participants received one or more doses of investigational product. Treatment with intravenous DHE, but not INP104 or nasal DHE, resulted in clinically relevant changes from baseline in systolic blood pressure (BP; 11.4 mmHg, 95% confidence interval [CI] 7.9-15.0) and diastolic BP (13.3 mmHg, 95% CI 9.4-17.1) at 5 min post-dose, persisting up to 30 min post-dose for systolic BP (6.3 mmHg; 95% CI 3.0-9.5) and diastolic BP (7.9 mmHg, 95% CI 3.9-11.9). None of the treatments produced any clinically meaningful electrocardiogram (ECG) changes. In STOP 301, 354 patients received one or more doses of INP104. Over 24 weeks, five patients (1.4%) experienced a non-serious, vascular treatment-emergent adverse event (TEAE). Minimal changes were observed for BP and ECG parameters over 24 or 52 weeks. Off-protocol concomitant use of triptans and other ergot derivatives did not result in any TEAEs. CONCLUSION: In two separate studies, INP104 demonstrated a favorable CV safety profile when used in a study population without CV-related contraindications.

Zincblende InAsxP1-x/InP Quantum Dot Nanowires for Telecom Wavelength Emission.

InAsxP1-x quantum dots (QDs) in InP nanowires (NWs) have been realized as a platform for emission at telecom wavelengths. These QDs are typically grown in NWs with the wurtzite crystal phase, but in this case, ultrathin diameters are required to achieve defect-free heterostructures, making the structures less robust. In this work, we demonstrate the growth of pure zincblende InAsxP1-x QDs in InP NWs, which enabled an increase in NW diameters to about 45 nm, achieved by employing Au-assisted vapor liquid solid growth in a chemical beam epitaxy system. We studied the growth of InP/InAsxP1-x heterostructures with different compositions to control the straight growth along the ⟨100⟩ direction and to tune the emission wavelength. Interestingly, we found that the growth mechanism for pure InAs QDs is different compared to that for InAsxP1-x alloy QDs. This allowed us to optimize different growth protocols to achieve straight growth of the final QD NWs. We successfully obtained the growth of InAsxP1-x QDs with a composition in the range of x = 0.24-1.00. By means of microphotoluminescence measurements, we demonstrate the tunability of the emission in dependence of the InAsxP1-x QD composition and morphology, remarkably observing an emission at the telecom O-band for a 10 nm thick QD with 80% of As content.

The Study on Single-Event Effects and Hardening Analysis of Frequency Divider Circuits Based on InP HBT Process.

The single-event effects (SEEs) of frequency divider circuits and the radiation tolerance of the hardened circuit are studied in this paper. Based on the experimental results of SEEs in InP HBTs, a transient current model for sensitive transistors is established, taking into account the influence of factors such as laser energy, base-collector junction voltage, and radiation position. Moreover, the SEEs of the (2:1) static frequency divider circuit with the InP DHBT process are simulated under different laser energies by adding the transient current model at sensitive nodes. The effect of the time relationship between the pulsed laser and clock signal are discussed. Changes in differential output voltage and the degradation mechanism of unhardened circuits are analyzed, which are mainly attributed to the cross-coupling effect between the transistors in the differential pair. Furthermore, the inverted output is directly connected to the input, leading to a feedback loop and causing significant logic upsets. Finally, an effective hardened method is proposed to provide redundancy and mitigate the impacts of SEEs on the divider. The simulation results demonstrate a notable improvement in the radiation tolerance of the divider.

Pachymic acid activates TP53INP2/TRAF6/caspase-8 pathway to promote apoptosis in renal cell carcinoma cells.

While pachymic acid (PA), a key component of Poria cocos (Schw.), has demonstrated anti-tumor effects in lung, breast, and pancreatic cancers, its impact on renal cell carcinoma (RCC) is unclear. This study evaluated the effect of PA on proliferation, migration, and apoptosis in human renal cancer A498 and ACHN cells as well as in cancer xenograft mice using wound scratch test, Western blotting, and co-immunoprecipitation assays. In a dose- and time-dependent manner, PA exhibited significant inhibition of RCC cell proliferation, migration, and invasion, accompanied by the induction of apoptosis. Additionally, PA upregulated the expression of tumor protein p53-inducible nuclear protein 2 (TP53INP2) and tumor necrosis factor receptor-associated factor 6 (TRAF6), which were downregulated in renal papillary and chromophobe carcinoma, resulting in inhibited tumor growth in mice. PA treatment elevated cleaved-caspase 3 and 8, and PARP levels, and facilitated TP53INP2 and TRAF6 binding to caspase 8, promoting its ubiquitination. Molecular docking revealed interactions between PA and TP53INP2, TRAF6. In summary, PA inhibits RCC development by upregulating TP53INP2 and promoting TRAF6-induced caspase 8 ubiquitination, activating apoptotic pathways.

TP53INP2 knockdown inhibits inflammatory response and apoptosis after spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) is a traumatic neurological disorder with limited therapeutic options. Tumor protein p53-inducible nuclear protein 2 (TP53INP2) is involved in the occurrence and development of various diseases, and it may play a role during SCI via affecting inflammation and neuronal apoptosis. This study investigated the associated roles and mechanisms of TP53INP2 in SCI. METHODS: Mouse and lipopolysaccharide (LPS)-induced SCI BV-2 cell models were constructed to explore the role of TP53INP2 in SCI and the associated mechanisms. Histopathological evaluation of spinal cord tissue was detected by hematoxylin and eosin staining. The Basso, Beattie, and Bresnahan score was used to measure the motor function of the mice, while the spinal cord water content was used to assess spinal cord edema. The expression of TP53INP2 was measured using RT-qPCR. In addition, inflammatory factors in the spinal cord tissue of SCI mice and LPS-treated BV-2 cells were measured using enzyme-linked immunosorbent assay. Apoptosis and related protein expression levels were detected by flow cytometry and western blot analysis, respectively. RESULTS: TP53INP2 levels increased in SCI mice and LPS-treated BV-2 cells. The results of in vivo and in vitro experiments showed that TP53INP2 knockdown inhibited the inflammatory response and neuronal apoptosis in mouse spinal cord tissue or LPS-induced BV-2 cells. CONCLUSIONS: After spinal cord injury, TP53INP2 was upregulated, and TP53INP2 knockdown inhibited the inflammatory response and apoptosis.

On-Chip Broadband, Compact TM Mode Mach-Zehnder Optical Isolator Based on InP-on-Insulator Platforms.

An integrated optical isolator is a crucial part of photonic integrated circuits (PICs). Existing optical isolators, predominantly based on the silicon-on-insulator (SOI) platform, face challenges in integrating with active devices. We propose a broadband, compact TM mode Mach-Zehnder optical isolator based on InP-on-insulator platforms. We designed two distinct magneto-optical waveguide structures, employing different methods for bonding Ce:YIG and InP, namely O2 plasma surface activation direct wafer bonding and DVS-benzocyclobutene (BCB) adhesive bonding. Detailed calculations and optimizations were conducted to enhance their non-reciprocal phase shift (NRPS). At a wavelength of 1550 nm, the direct-bonded waveguide structure achieved a 30 dB bandwidth of 72 nm with a length difference of 0.256 µm. The effects of waveguide arm length, fabrication accuracy, and dimensional errors on the device performance are discussed. Additionally, manufacturing tolerances for three types of lithographic processes were calculated, serving as references for practical manufacturing purposes.

Nanowire Array Breath Acetone Sensor for Diabetes Monitoring.

Diabetic ketoacidosis (DKA) is a life-threatening acute complication of diabetes characterized by the accumulation of ketone bodies in the blood. Breath acetone, a ketone, directly correlates with blood ketones. Therefore, monitoring breath acetone can significantly enhance the safety and efficacy of diabetes care. In this work, the design and fabrication of an InP/Pt/chitosan nanowire array-based chemiresistive acetone sensor is reported. By incorporation of chitosan as a surface-functional layer and a Pt Schottky contact for efficient charge transfer processes and photovoltaic effect, self-powered, highly selective acetone sensing is achieved. The sensor has exhibited an ultra-wide acetone detection range from sub-ppb to >100 000 ppm level at room temperature, covering those in the exhaled breath from healthy individuals (300-800 ppb) to people at high risk of DKA (>75 ppm). The nanowire sensor has also been successfully integrated into a handheld breath testing prototype, the Ketowhistle, which can successfully detect different ranges of acetone concentrations in simulated breath samples. The Ketowhistle demonstrates the immediate potential for non-invasive ketone monitoring for people living with diabetes, in particular for DKA prevention.

Eu3+-based InP/ZnS quantum dot fluorescence platform for multi-color and sensitive visualization of tetracycline.

A turn-on type ratiometric fluorescence sensing system of blue quantum dot Eu-MPA-InP/ZnS was established for multi-color visualization determination of tetracycline (TC). Mercaptopropionic acid (MPA)-capped InP/ZnS quantum dots (MPA-InP/ZnS QDs) both modify the hydrophilicity of InP/ZnS QDs and serve as a scaffold for coordinating of Eu3+ ions. The blue fluorescence of Eu-MPA-InP/ZnS at 478 nm is reduced by the TC through the inner filter effect (IFE) under a single excitation wavelength of 365 nm. Rich colour gradients and a highly discriminative colour change were features of this multicolour response to TC, which allowed visual quantification of TC in a dose-dependent manner. Furthermore, by cross-linking Eu-MPA-InP/ZnS with agarose (Aga.), a mouldable Eu-MPA-InP/ZnS@Aga 96-well gel sensing device was designed to serve as a handheld sensor for on-site detection of TC. This probe expands the use of InP QDs in analytical sensing and has been effectively applied to the visual detection of tetracycline in milk and the environment.

Positive Trions in InP/ZnSe/ZnS Colloidal Nanocrystals.

InP-based colloidal nanocrystals are being developed as an alternative to cadmium-based materials. However, their optical properties have not been widely studied. In this paper, the fundamental magneto-optical properties of InP/ZnSe/ZnS nanocrystals are investigated at cryogenic temperatures. Ensemble measurements using two-photon excitation spectroscopy revealed the band-edge hole state to have 1Sh symmetry, resolving some controversy on this issue. Single nanocrystal microphotoluminescence measurements provided increased spectral resolution that facilitated direct detection of the lowest energy confined acoustic phonon mode at 0.9 meV, which is several times smaller than the previously reported values for similar nanocrystals. Zeeman splitting of narrow spectral lines in a magnetic field indicated a bright trion emission. A simple trion model was used to identify a positive trion charge. Furthermore, the Zeeman split spectra allowed the direct measurement of both the electron and hole g-factors, which match existing theoretical predictions.

Ultra-Broadband Ultraviolet-Visible Light-Short Wavelength Infrared InGaAs Focal Plane Arrays via n-InP Contact Layer Removal.

PIN InGaAs short wavelength infrared (SWIR) focal plane array (FPA) detectors have attracted extensive attention due to their high detectivity, high quantum efficiency, room temperature operation, low dark current, and good radiation resistance. Furthermore, InGaAs FPA detectors have wide applications in many fields, such as aviation safety, biomedicine, camouflage recognition, and infrared night vision. Recently, extensive research has been conducted on the extension of the response spectrum from short wavelength infrared (SWIR) to visible light (VIS) through InP substrate removal and reserving the n-InP contact layer. However, there is little research on the absorption of InGaAs detectors in the ultraviolet (UV) band. In this paper, we present an ultra-broadband UV-VIS-SWIR 640 × 512 15 µm InGaAs FPA detector by removing the n-InP contact layer in the active area and reserving the InP contact layer around the pixels for n contact, creating incident light to be directly absorbed by the In0.53Ga0.47As absorption layer. In addition, the optical absorption characteristics of InGaAs infrared detectors with and without an n-InP contact layer are studied theoretically. The test results show that the spectral response is extended to the range of 200-1700 nm. The quantum efficiency is higher than 45% over a broad wavelength range of 300-1650 nm. The operability is up to 99.98%, and the responsivity non-uniformity is 3.28%. The imaging capability of InGaAs FPAs without the n-InP contact layer has also been demonstrated, which proves the feasibility of simultaneous detection for these three bands.

Composition, Optical Resonances, and Doping of InP/InGaP Nanowires for Tandem Solar Cells: a Micro-Raman Analysis.

We present a micro-Raman study of InP/InGaP tandem junction photovoltaic nanowires. These nanowires render possible InGaP compositions that cannot be made in thin films due to strain. The micro-Raman spectra acquired along the nanowires reveal the existence of compositional changes in the InGaP alloy associated with the doping sequence. The heavily Zn-doped InxGa1-xP (x is the In molar fraction) side of the tunnel diode is Ga rich, x = 0.25, with respect to the n-type and intrinsic segments of the top cell, which are close to the nominal composition of the NWs (x = 0.35). The p-type end segment is still Ga-rich. Electromagnetic resonances are observed in the tunnel diode. The Raman signal arising from the InGaP side of the tunnel diode is significantly enhanced. This enhancement permits the observation of a Raman mode that can be associated with an LO phonon plasmon coupled mode (LOPCM). This mode has not been previously reported in the literature of InGaP, and it permits the Raman characterization of the tunnel diode. The analysis of this mode and its relation to the LO phonon modes of the alloy, InP-like and GaP-like, allows to establish an apparent one-mode behavior for the phonon plasmon coupling. It indicates that hole plasma couples to the GaP-like LO mode. The LOPCMs are modeled using the Lindhard Mermin formalism for the dielectric function.

Size control of InP nanowires byin situannealing and its application to the formation of InAsP quantum dots.

We carried outin situannealing of InP nanowires (NWs) in a metal-organic vapor phase epitaxial (MOVPE) growth reactor to control and reduce the tip size of InP NWs. InP NWs were grown by selective-area (SA) MOVPE on partially masked (111)A InP substrates, and annealing was successively applied in tertiarybutylphosphine (TBP) ambient. Initially, the InP NWs had a hexagonal cross-section with{112¯}facets vertical to the substrates; they became tapered, and the edges were rounded by annealing. By appropriately selecting the annealing temperature and initial NW diameter, the tip size of the NW was reduced and NWs with a tip size of 20 nm were successfully formed. Subsequently, a thin InAsP layer was grown on the annealed NWs and their photoluminescence was investigated at low temperatures. The characterization results indicated the formation of InAsP quantum dots (QDs) emitting in the telecom band. Our approach is useful for reducing the size of the NWs and for the controlled formation of InAsP QDs embedded in InP NWs in photonic devices compatible with telecom bands.

A cathodoluminescence study of InP/InGaP axially heterostructured NWs for tandem solar cells.

Axially heterostructured nanowires (NWs) constitute a promising platform for advanced electronic and optoelectronic nanodevices. The presence of different materials in these NWs introduces a mismatch resulting in complex strain distributions susceptible of changing the band gap and carrier mobility. The growth of these NWs presents challenges related to the reservoir effect in the catalysts droplet that affect to the junction abruptness, and the occurrence of undesired lateral growth creating core-shell heterostructures that introduce additional strain. We present herein a cathodoluminescence (CL) analysis on axially heterostructured InP/InGaP NWs with tandem solar cell structure. The CL is complemented with micro Raman, micro photoluminescence (PL), and high resolution transmission electron microscopy measurements. The results reveal the zinc blende structure of the NWs, the presence of a thin InGaP shell around the InP bottom cell, along with its associated strain, and the doping distribution.

Growth Control of InP/ZnSe Heterostructured Nanocrystals.

The morphology of heterostructured semiconductor nanocrystals (h-NCs) dictates the spatial distribution of charge carriers and their recombination dynamics and/or transport, which are the main performance indicators of photonic applications utilizing h-NCs. The inability to control the morphology of heterovalent III-V/II-VI h-NCs composed of heavy-metal-free elements hinders their practical use. As a case study of III-V/II-VI h-NCs, the growth control of ZnSe epilayers on InP NCs is demonstrated here. The anisotropic morphology in InP/ZnSe h-NCs is attributed to the facet-dependent energy costs for the growth of ZnSe epilayers on different facets of InP NCs, and effective chemical means for controlling the growth rates of ZnSe on different surface planes are demonstrated. Ultimately, this article capitalizes on the controlled morphology of InP/ZnSe h-NCs to expand their photophysical characteristics from stable and pure emission to environment-sensitive one, which will facilitate their use in a variety of photonic applications.