The timing of green product introduction in relation to technological evolution

<p>As a result of the rising awareness of environmental issues and increasingly stringent regulations, the ability of a business to manage environmentally friendly products represents an important competitive edge. This paper presents a study of the impacts of two types of technological solutions, namely, Zero Sum and Synergy, on strategies for timing the introduction of green products. We have developed mathematical models to determine the optimal price, traditional quality, and environmental quality required to maximize profit. In addition, we discuss how differentiation in environmental quality and customer patience impact the choice of product introduction strategies under the commitment and no-commitment scenarios. We also investigate how Zero Sum and Synergy interact with choice. The results show that a business tends to adopt a simultaneous introduction strategy when the differentiation in market condition for environmental quality is high, customer is patient, and/or the business employs the Synergy technology. In addition, we determine that this strategy change is less likely in the commitment scenario, when the technology changes from Zero Sum to Synergy.</p

Generic Nanomaterial Positioning by Carrier and Stationary Phase Design

A generic approach for deploying various types of synthetic nanomaterials, including single-walled carbon nanotubes and nanoparticles, at well-defined locations on substrates is presented. The assembly is achieved through the complementary design of the stationary and carrier phases and utilizes the dewetting process during which polymer-encapsulated nanomaterials are delivered and positioned on predefined locations of substrates. Covalent modification of the nano-objects is not required for the building block positioning, therefore, preserving their intrinsic chemical and physical properties. The potency of this new approach is demonstrated for various synthetic nanomaterials, such as polystyrene, silica, and gold nanoparticles as well as single-walled carbon nanotubes, showing highly specific and direct patterning of cm2 areas using a generic assembly strategy

Patterned p-Doping of InAs Nanowires by Gas-Phase Surface Diffusion of Zn

Gas phase p-doping of InAs nanowires with Zn atoms is demonstrated as an effective route for enabling postgrowth dopant profiling of nanostructures. The versatility of the approach is demonstrated by the fabrication of high-performance gated diodes and p-MOSFETs. High Zn concentrations with electrically active content of ∼1 × 1019 cm−3 are achieved which is essential for compensating the electron-rich surface layers of InAs to enable heavily p-doped structures. This work could have important practical implications for the fabrication of planar and nonplanar devices based on InAs and other III−V nanostructures which are not compatible with conventional ion implantation processes that often cause severe lattice damage with local stoichiometry imbalance

Monolayer Resist for Patterned Contact Printing of Aligned Nanowire Arrays

Monolayer Resist for Patterned Contact Printing of Aligned Nanowire Array

Utilizing a NaOH Promoter to Achieve Large Single-Domain Monolayer WS₂ Films via Modified Chemical Vapor Deposition

Because of their fascinating properties, two-dimensional (2D) nanomaterials have attracted a lot of attention for developing next-generation electronics and optoelectronics. However, there is still a lack of cost-effective, highly reproducible, and controllable synthesis methods for developing high-quality semiconducting 2D monolayers with a sufficiently large single-domain size. Here, utilizing a NaOH promoter and W foils as the W source, we have successfully achieved the fabrication of ultralarge single-domain monolayer WS2 films via a modified chemical vapor deposition method. With the proper introduction of a NaOH promoter, the single-domain size of monolayer WS2 can be increased to 550 μm, while the WS2 flakes can be well controlled by simply varying the growth duration and oxygen concentration in the carrier gas. Importantly, when they are fabricated into global backgated transistors, WS2 devices exhibit respectable peak electron mobility up to 1.21 cm2 V–1 s–1, which is comparable to those of many state-of-the-art WS2 transistors. Photodetectors based on these single-domain WS2 monolayers give an impressive photodetection performance with a maximum responsivity of 3.2 mA W–1. All these findings do not only provide a cost-effective platform for the synthesis of high-quality large single-domain 2D nanomaterials, but also facilitate their excellent intrinsic material properties for the next-generation electronic and optoelectronic devices

Mechanistic Characteristics of Metal-Assisted Chemical Etching in GaAs

Because of the unique physical properties, various GaAs micro- and nanostructures have attracted increasing research attention for many technical applications such as solar cells, light-emitting diodes, and field-effect transistors. In this regard, numerous fabrication techniques have been explored, and among all, metal-assisted chemical etching is successfully applied to GaAs in order to achieve cost-effective, large-scale, and complex structures. However, the detailed explanations as well as the corresponding etching mechanism have not been reported until now or simply relied on the hole injection model of Si in order to explain the phenomenon. In this work, we perform a more systematic study to further explore and assess the etching phenomenon of GaAs employing the Au catalyst and the [KMnO₄/H₂SO₄] etch system. It is revealed that the anisotropic etching behavior of GaAs is predominantly due to the Au-induced surface defects at the Au/GaAs interface, which makes the particular area more prone to oxidation and thus results in the simple directional wet etching; for that reason, more anisotropic etch is obtained for the Au pattern with higher edge-to-surface-area ratio. All these findings not only offer additional insight into the MacEtch process of GaAs but also provide essential information on different etching parameters in manipulating this anisotropic wet etching to achieve the fabrication of complex GaAs structures for technological applications

Optical Properties of In_2<i>x</i>Ga_{2–2<i>x</i>}O₃ Nanowires Revealed by Photoacoustic Spectroscopy

Group III oxides, such as In2O3 and Ga2O3, have proved to be good candidates as active materials for novel electronic devices, including high-mobility transistors, gas sensors, and UV photodetectors. The ability to tune optical and electronic properties is provided by alloying In2xGa2–2xO3 (InGaO) in a broad compositional range. Further development of InGaO compounds in the form of nanowires (NWs) would overcome the technological limitations, such as the substrate crystal lattice mismatch and the inability to fabricate high quality structures above the critical thickness. In this work, optical properties of alloyed InGaO NWs in a wide compositional range are carefully assessed. Unlike classical optical characterization methods, photoacoustic spectroscopy reveals the fundamental absorption edge despite the strong light scattering in porous and randomly oriented nanowires structure. An unusual compositional band gap dependence is also observed, giving insight into the phase segregation effect and increased quality of mixed NWs. In addition, photoacoustic measurements disclose potential applications of InGaO NWs in remote, light-driven loudspeakers because of intense photoacoustic effect in nanowire ensembles in this material system

Wafer-Scale, Sub-5 nm Junction Formation by Monolayer Doping and Conventional Spike Annealing

We report the formation of sub-5 nm ultrashallow junctions in 4 in. Si wafers enabled by the molecular monolayer doping of phosphorus and boron atoms and the use of conventional spike annealing. The junctions are characterized by secondary ion mass spectrometry and noncontact sheet resistance measurements. It is found that the majority (∼70%) of the incorporated dopants are electrically active, therefore enabling a low sheet resistance for a given dopant areal dose. The wafer-scale uniformity is investigated and found to be limited by the temperature homogeneity of the spike anneal tool used in the experiments. Notably, minimal junction leakage currents (2) are observed that highlights the quality of the junctions formed by this process. The results clearly demonstrate the versatility and potency of the monolayer doping approach for enabling controlled, molecular-scale ultrashallow junction formation without introducing defects in the semiconductor

Wafer-Scale Assembly of Highly Ordered Semiconductor Nanowire Arrays by Contact Printing

Controlled and uniform assembly of “bottom-up” nanowire (NW) materials with high scalability presents one of the significant bottleneck challenges facing the integration of nanowires for electronic applications. Here, we demonstrate wafer-scale assembly of highly ordered, dense, and regular arrays of NWs with high uniformity and reproducibility through a simple contact printing process. The assembled NW pitch is shown to be readily modulated through the surface chemical treatment of the receiver substrate, with the highest density approaching ∼8 NW/μm, ∼95% directional alignment, and wafer-scale uniformity. Such fine control in the assembly is attained by applying a lubricant during the contact printing process which significantly minimizes the NW−NW mechanical interactions, therefore enabling well-controlled transfer of nanowires through surface chemical binding interactions. Furthermore, we demonstrate that our printing approach enables large-scale integration of NW arrays for various device structures on both rigid silicon and flexible plastic substrates, with a controlled semiconductor channel width ranging from a single NW (∼10 nm) up to ∼250 μm, consisting of a parallel array of over 1250 NWs and delivering over 1 mA of ON current