3-D stacked CMOS transistors offer an opportunity to enable further standard cell and SRAM scaling, making them a promising transistor architecture to extend Moore's law. We review state-of-the-art approaches for achieving 3-D CMOS stacking. The sequential approach is highlighted by fabricating Ge PMOS stacked via layer transfer on top of Si NMOS, and self-aligned approach is demonstrated by simultaneously fabricated NMOS-on-PMOS multi-nanoribbon Si transistors. Both approaches showcase a well-balanced CMOS inverter built from transistors in top and bottom device layers.

Lanthanide monopnictide (Ln‐V) nanoparticles embedded within III–V semiconductors, specifically in In 0.53 Ga 0.47 As, are interesting for thermoelectric applications. The electrical conductivity, Seebeck coefficient, and power factor of co‐deposited TbAs:InGaAs over the temperature range of 300–700 K are reported. Using Boltzmann transport theory, it is shown that TbAs nanoparticles in InGaAs matrix give rise to an improved Seebeck coefficient due to an increase in scattering, such as ionized impurity scattering. TbAs nanoparticles act as electron donors in the InGaAs matrix while having minimal effects on electron mobility, and maintain high electrical conductivity. There is further evidence that TbAs nanoparticles act as energy dependent electron scattering sites, contributing to an increased Seebeck coefficient at high temperature. These results show that TbAs:InGaAs nanocomposite thinfilms containing low concentrations, specifically 0.78% TbAs:InGaAs, display high electrical conductivity, reduced thermal conductivity, improved Seebeck coefficient, and demonstrated ZT of power factors as high as 7.1 × 10 −3 W K −2 m −1 and ZT as high as 1.6 at 650 K.

The incorporation of lanthanide pnictide nanoparticles and films into III-V matrices allows for semiconductor composites with a wide range of potential optical, electrical, and thermal properties, making them useful for applications in thermoelectrics, tunnel junctions, phototconductive switches, and as contact layers. The similarities in crystal structures and lattice constants allow them to be epitaxially incorporated into III-V semiconductors with low defect densities and high overall film quality. A variety of growth techniques for these composites with be discussed, along with their growth mechanisms and current applications, with a focus on more recent developments. Results obtained from molecular beam epitaxy film growth will be highlighted, although other growth techniques will be mentioned. Optical and electronic characterization along with the microscopy analysis of these composites is presented to demonstrate influence of nanoinclusion composition and morphology on the resulting properties of the composite material.

Significant research effort has been placed into the use of III–V compound semiconductors, including InGaAs as channel materials in CMOS logic devices due to their superior electron mobilities compared to Si and other more conventional semiconductor materials. One of the major factors preventing industrial adoption of InGaAs as a channel material involves the minimization of source and drain contact resistances. To understand challenges to minimization of contact resistance, this work will outline the effectiveness of several doping approaches that have been attempted for n-type InGaAs including the use of silicon as a dopant and the effectiveness of each approach in achieving the highest level of activation possible. Previous and recently reported dopant diffusion behaviors are also included and discussed.

This article has been removed: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The publisher sincerely regrets that due to a production error this paper has been prematurely published albeit clear indications from the Authors and Editors that it should not be included in a regular issue but it is to be incorporated as part of the upcoming Special Issue on Doping in Nanodevices. This error bears absolutely no reflection on the article content, the Special Issue Editors or the article Authors. The publisher apologizes very much to the Authors and the readers for this unfortunate error. The original article can be found at 10.1016/j.mssp.2016.12.017 (volume 62, Page number 171-179).

Significant research effort has been placed into the use of III-V compound semiconductors, including InGaAs as channel materials in CMOS logic devices due to their superior electron mobilities compared to Si and other more conventional semiconductor materials. One of the major factors preventing industrial adoption of InGaAs as a channel material involves the minimization of source and drain contact resistances. To understand challenges to minimization of contact resistance, this work will outline the effectiveness of several doping approaches that have been attempted for n-type InGaAs including the use of silicon as a dopant and the effectiveness of each approach in achieving the highest level of activation possible. Previous and recently reported dopant diffusion behaviors are also included and discussed.

The evolution of implant damage in InGaAs is studied for electrically active Si+ and isoelectronic P+ implants. Extrinsic loops formed by excess interstitials are shown to be less stable upon annealing for n-type Si+ implants relative to isoelectronic P+ implants. Damage created by P+ implants into heavily n-doped InGaAs is also shown to be less stable than damage created by P+ implants into unintentionally doped InGaAs indicating that the background doping concentration can significantly effect the evolution of implant damage upon annealing. Previous results have suggested that the electrical activation and diffusion behavior of n-type dopants, like Si in InGaAs, may be strongly influenced by vacancy concentration. TEM results in this study also suggest that heavy n-type doping in InGaAs results in the formation of a large population of vacancy defects that enhance the dissolution or inhibit formation of interstitial loops. (c) 2015 The Electrochemical Society. All rights reserved.

We explore the growth and characterization of ErAs:GaBiAs as a candidate material for terahertz generation and detection via photoconductive switches. Spectrophotometry shows that the incorporation of small amounts of bismuth causes a reduction in the band gap, making these materials compatible with fiber-coupled lasers. ErAs pins the Fermi level within the band gap, causing high dark resistance while maintaining high mobility, shown by Hall effect measurements. Finally, transient absorption (optical pump, optical probe) measurements show that the ErAs provides a carrier recombination pathway, causing short carrier lifetimes. These material properties make ErAs:GaBiAs an interesting choice for fiber-coupled photoconductive switches.

We report on the molecular beam epitaxy growth and characterization of TbAs films. In situ reflection high energy electron diffraction and ex situ high resolution X-ray diffraction, reciprocal space mapping, and both scanning and transmission electron microscopy are used to confirm the complete film growth and study the films' morphology. Spectrophotometry measurements provide the energy of optical transitions, revealing a red shift in optical band gap with increasing thickness. The Hall effect measurements show temperature insensitive carrier concentrations, resistivities, and mobilities. The carrier concentration decreases and resistivity increases with increasing film thickness; mobility appears thickness independent. The films' reflectivity, obtained via Fourier transform infrared spectroscopy, shows a possible Drude edge that differs from the trend of other lanthanide monopnictides. These measurements show that TbAs is a degenerately doped semiconductor with a combination of electronic and optical properties that is dissimilar to other lanthanide monopnictides.

Layered semiconductor hyperbolic metamaterials for the mid-infrared are grown by molecular beam epitaxy using a single material system, doped and undoped InAs. The onset wavelength for metamaterial behavior can be tuned from 5.8μm to beyond 10μm, while the fill factor ranges from 0.25 to 0.75, resulting in designer optical behavior. The reflection and transmission behavior were studied by Fourier transform spectroscopy and modeled using effective medium theory. We also conducted a geometric optics experiment to demonstrate negative refraction of our materials.

Light is one of the most important media to transport information. Optical metamaterials are artificial materials that are fabricated on the subwavelength scale so people can manipulate light-matter interactions in a fascinating way that conventional materials are not able to. Optical metamaterials have unique optical properties and may find applications in subwavelength imaging, novel waveguiding, thermal emission engineering, and biosensing, ☐ Multilayer hyperbolic metamaterial (HMM) is one kind of optical metamaterials that are composed of alternating metal/dielectric layers. They are easy to fabricate and have designer properties. Though there are extensive studies about HMM in the visible range, the potential of HMM in the infrared remains to be fully discovered. To move HMM study to the infrared, we first need to choose suitable materials. III-V semiconductors, such as InAs, have been proven to be promising plasmonic materials for the infrared. ☐ This dissertation demonstrates semiconductor HMMs created from various material classes: Si:InAs/InAs, Si:InGaAs/InAlAs, and Si:InAs/AlSb. Discontinuity of the Brewster angle and negative refraction, two hallmarks of HMM, were observed in our materials. Also, the properties of semiconductor HMM are designer by adjusting the structure parameters. ☐ This dissertation also explores the volume plasmon polariton (VPP) modes in semiconductor HMMs. VPP modes are modes with large wavevectors and are usually not supported by conventional materials. They are the foundation of many proposed applications based on HMMs. Up to five VPP modes were observed in our materials, and we found that Si:InAs/AlSb HMM exhibits the best VPP modes among all other semiconductor HMMs. ☐ We also investigated the optimization of the growth of highly Si-doped InAs by using bismuth surfactant. We show that the optical properties, electrical properties and surface morphology of Si:InAs were significantly improved. The growth window of Si:InAs is broadened, making it easier to integrate Si:InAs with other III-V semiconductors. ☐ In the future, III-V semiconductor HMMs will be integrated with other semiconductor structures, including quantum wells, quantum dot, and quantum cascade laser. Such compound structures will lead to new physical phenomena and novel optoelectronic devices with higher efficiency.

Continued effort has been placed on maximizing activation while controlling the diffusion of silicon doping in InGaAs for present and future complementary metal-oxide semiconductor devices. In order to explore the diffusion and activation behavior, Si marker layers were grown in InGaAs on InP by molecular beam epitaxy. The nature of Si diffusion was explored using a series of isoelectronic implants to introduce excess point defects near the layer. It was observed that excess interstitials reduce the Si diffusion consistent with a vacancy-driven diffusion mechanism. A diffusion and activation model implemented in the Florida object oriented process simulator has been developed to predict silicon diffusion behavior over a variety of temperatures and times. Using current and previous experimental data and complimentary density functional theory results, the diffusion model employs the SiIII–VIII pair as the primary mechanism for silicon diffusion in InGaAs.

There is a renewed interest in integrating high mobility III-V channel materials into sub 10 nm nMOS devices but the continued scaling of devices has resulted in the need to create contacts and source/drains with ultra low contact resistivities in order to reduce current losses. This study investigates thermal stability of Si dopants incorporated via MBE growth and ion implantation as potential methods to create heavily-doped, low resistance source/drain regions in III-V channel devices. For this study, the electrical activation and diffusion of Si active layers in In 0.53 Ga 0.47 As formed by a 10 keV, 5×10 14 cm -2 Si implant and MBE growth doping with a peak Si concentration of 7×10 19 cm -3 were investigated as a function of post growth and post-implant isochronal annealing. While most previous studies conclude that MBE doping can achieve higher active Si concentrations than ion implantation, the results of this study show conclusively that electrically active Si concentrations above 1.4×10 19 cm -3 formed by MBE doping are prone to deactivation upon thermal treatment after growth whereas ion-implantation shows no metastable activation behavior. Significant Si deactivation in MBE doped substrates is shown to occur before the onset of Si diffusion whereas saturated activation in ion implanted substrates does not occur until diffusion is observed. Upon annealing at sufficiently high temperatures to cause Si diffusion, the electrical activation of Si in MBE doped substrates and ion implanted Si are shown to converge to a stable activation limit of 1.4×10 19 cm -3 . The common activation limit upon Si profile motion for both Ion implanted and growth doped Si active layers after thermal annealing at 750°C suggests that the maximum stable electrical activation of Si is an intrinsic property of In 0.53 Ga 0.47 As. Si diffusivity has also been calculated from SIMS results in both ion-implanted substrates and growth-doped substrate and Si diffusion in MBE doped substrates was observed to be nearly three times as fast as ion implanted substrates presumably due to the observed concentration dependent diffusion effects. The mechanism of Si diffusion and its relation to the observed concentration dependent diffusion and electrical activation behavior in both materials are also discussed. Figure 1

We propose and systematically justify a band structure for TbAs nanoparticles in GaAs and In0.53Ga0.47As host matrices. Fluence-dependent optical-pump terahertz-probe measurements suggest the TbAs nanoparticles have a band gap and provide information on the carrier dynamics, which are determined by the band alignment. Spectrophotometry measurements provide the energy of optical transitions in the nanocomposite systems and reveal a large blue shift in the absorption energy when the host matrix is changed from In0.53Ga0.47As to GaAs. Finally, Hall data provides the approximate Fermi level in each system. From this data, we deduce that the TbAs:GaAs system forms a type I (straddling) heterojunction and the TbAs:In0.53Ga0.47As system forms a type II (staggered) heterojunction.

The effect of thermal annealing on the net donor concentration and diffusion of Si in In0.53Ga0.47As is compared for electrically active layers formed by ion implantation versus molecular beam epitaxy (MBE). Upon thermal treatment at temperatures of 700 °C or higher for 10 min, both ion implanted and growth-doped substrates converge to a common net donor solubility. These results indicate that while MBE doped substrates typically exhibit higher active concentrations relative to implanted substrates, the higher active Si concentrations from MBE growth are metastable and susceptible to deactivation upon subsequent thermal treatments after growth. Active Si doping concentrations in MBE doped material and ion-implanted materials are shown to converge toward a fixed net donor solubility limit of 1.4 × 1019 cm−3. Secondary ion mass spectroscopy of annealed samples indicates that the diffusivity of Si in MBE doped substrates is higher than those of ion implanted substrates presumably due to concentration-dependent diffusion effects.

The thermal stability of Si dopants incorporated during growth and via ion implantation was investigated as a function of annealing time and temperature. Ion implanted samples show a maximum achievable doping concentration of 1.4×1019 cm-3. Growth doped samples exhibit higher post growth electrical activations than achievable in ion implanted samples but subsequent thermal processing at 750°C for 10 minutes is shown to deactivate heavily doped (3×1019 cm-3) MBE doped substrates to the same active doping concentration of 1.4×1019 cm-3 suggesting a common thermodynamic limit to Si activation in InGaAs.

Cross-plane thermoelectric transport in p-type La0.67Sr0.33MnO3/LaMnO3 oxide metal/semiconductor superlattices Report Title The cross-plane thermoelectric transport properties of La0.67Sr0.33MnO3(LSMO)/LaMnO(LMO) oxide metal/semiconductor superlattices were investigated. The LSMO and LMO thin-?lm depositions were performed using pulsed laser deposition to achieve low resistivity constituent materials for LSMO/LMO superlattice heterostructures on (100)-strontium titanate substrates. X-ray diffraction and high-resolution reciprocal space mapping indicate that the superlattices are epitaxial and pseudomorphic. Cross-plane devices were fabricated by etching cylindrical pillar structures in superlattices using inductively, this coupled-plasma reactive-ion etching. The crossplane electrical conductivity data for LSMO/LMO superlattices reveal a lowering of the effective barrier height to 223 meV as well as an increase in cross-plane conductivity by an order of magnitude compared to high resistivity superlattices. These results suggest that controlling the oxygen de?ciency in the constituent materials enables modi? cation of the effective barrier height and increases the cross-plane conductivity in oxide superlattices. The cross-plane LSMO/LMO superlattices showed a giant Seebeck coef?cient of 2560 uV/K at 300 K that increases to 16640 uV/K at 360 K. The giant increase in the Seebeck coef?cient with temperature may include a collective contribution from the interplay of charge, spin current, and phonon drag. The low resistance oxide superlattices exhibited a room temperature cross-plane thermal conductivity of 0.92 W/m K, this indicating that the suppression of thermal conductivities due to the interfaces is preserved in both low and high resistivity superlattices. The high Seebeck coef? cient, the order of magnitude improvement in cross-plane conductivity, and the low thermal conductivity in LSMO/LMO superlattices resulted in a two order of magnitude increase in cross-plane power factor and thermoelectric ?gure of merit (ZT), compared to the properties of superlattices with higher resistivity that were reported previously. The temperature dependence of the cross-plane power factor in low resistance superlattices suggests a direction for further investigations of the potential LSMO/LMO oxide superlattices for thermoelectric devices. Cross-plane thermoelectric transport in p-type La0.67Sr0.33MnO3/LaMnO3 oxide metal/semiconductor superlattices Approved for public release; distribution is unlimited. 54530.29-MS-DRP REPORT DOCUMENTATION PAGE (SF298) (Continuation Sheet) Continuation for Block 13