Future Large-scale Integration Research Articles

High Power Mid-Infrared Quantum Cascade Lasers Grown on Si

This article details the demonstration of a strain-balanced, InP-based mid-infrared quantum cascade laser structure that is grown directly on a Si substrate. This is facilitated by the creation of a metamorphic buffer layer that is used to convert from the lattice constant of Si (0.543 nm) to that of InP (0.587 nm). The laser geometry utilizes two top contacts in order to be compatible with future large-scale integration. Unlike previous reports, this device is capable of room temperature operation with up to 1.6 W of peak power. The emission wavelength at 293 K is 4.82 μm, and the device operates in the fundamental transverse mode.

High performance few-layer MoS2 transistor arrays with wafer level homogeneity integrated by atomic layer deposition

Wafer-level integration of 2D transition metal disulfide is the key factor for future large-scale integration of the continuously scaling-down devices, and has attracted great attention in recent years. Compared with other ultra-thin film growth methods, atomic layer deposition (ALD) has the advantages of excellent step coverage, uniformity and thickness controllability. In this work, we synthesized large-scale and thickness-controllable MoS2 films on sapphire substrate by ALD at 150 °C with molybdenum hexcarbonyl and hexamethyldisilathiane (HMDST) as precursors followed by high-temperature annealing in sulfur atmosphere. HMDST is introduced for the first time to enable a toxic-free process without hazardous sulfur precursors such as H2S and CH3SSCH3. The synthesized MoS2 retains the inherent benefits from the ALD process, including thickness controllability, reproducibility, wafer-level thickness uniformity, and high conformity. Finally, field-effect transistor (FET) arrays were fabricated based on the large-area ALD MoS2 films. The top-gate FETs exhibited excellent electrical performance such as high on/off current ratio over 103 and peak room-temperature mobility up to 11.56 cm2 V−1 s−1. This work opens up an attractive approach to realize the application of high-quality 2D materials with wafer scale homogeneity.

Applications of three-dimensional LSI

Abstract

Single InGaN nanocolumn spectroscopy

We report on the spectroscopy of single InGaN/GaN nanocolumns that are site-controlled nanostructures allowing for pixel-like large-scale integration. A single nanocolumn shows several narrow photoluminescence peaks at around 600 nm at 20–90 K, the linewidth of which ranges between 0.3 and 10 meV. We have observed an interesting temperature dependence of the integrated intensity, the maximum being around 40–70 K, which suggests the existence of efficient carrier injection channels from localized states. The results show that the optical properties of single nanocolumns are favorable for the future large-scale integration of single-photon emitters and qubits.

Bidirectional multiplexing of heralded single photons from a silicon chip

We demonstrate integrated spatial multiplexing of heralded single photons generated from a single 96 μm long silicon photonic crystal waveguide in a bidirectional pump configuration. By using a low-loss fiber-coupled opto-ceramic switch, the multiplexing technique enhances the brightness of the single photon source by 51.2±4.0% while maintaining the coincidence-to-accidental ratio. Compared with the demonstration of multiplexing two individual sources, the bidirectional pump scheme represents a twofold reduction in the footprint of nonlinear devices for future large-scale integration of on-chip single photon sources. The 51.2±4.0% gain will make any quantum operation requiring n photons 1.5(n) times faster.

Managing and analysing brain data through use of digital atlasing tools and infrastructures

Managing and analysing brain data through use of digital atlasing tools and infrastructures

Characteristics of Al substituted nanowires fabricated by self-aligned growth for future large scale integration interconnects

Substituted Al nanowires for use in future large scale integration interconnects were fabricated by self-aligned growth. The resistivity of an Al substituted nanowire 80 nm in width, 100 nm in height, and 20 μm in length was 4.7 μΩ cm, which is 48% lower than that of an Al nanowire with the same dimensions fabricated using a bottom-up approach. The variation in the resistivity was in a narrow range (14%) over a Si wafer. The TEM imaging revealed that the Al substituted nanowire had a bamboo-like structure with grains larger than 1.6 μm. The electromigration activation energy was 0.72 eV, which is comparable to that of a pure Al wire with a bamboo-like structure. The product of the critical current density and wire length was 1.3 × 103 A/cm at 250 °C; 2.1 times higher than that of a pure Al wire with a polycrystalline structure. The acceleration of electromigration due to current density was 2.0, indicating that incubation time dominates electromigration lifetime. The prolonged incubation time observed in the electromigration test is attributed to the reduction in electromigration-induced mass transport due to the microstructure of the Al substituted nanowire. Even the formation of a small void immediately after incubation may be a fatal defect for nanoscale Al wires.

The Design of Single Mode Large Cross-section Glass-based Waveguides for Photonic Integrated Circuits

This paper presents our recent simulation results and novel designs of single mode large cross-section glass-based waveguides for photonic integrated circuits (PICs). Simulations were performed using an in-house Finite Difference (FD) based mode solver and the FD Beam propagation Method (FD-BPM). Our simulation results show that this innovative technology could provide a simplified means to couple optical energy efficiently between optical components in a single chip. This would provide the base for the future large-scale integration of optical components in PICs. The novel idea of using single mode large cross-section glass-based waveguides as an optical integration platform is an evolutionary innovative solution for the monolithic integration of optical components, in which the glass-based structures act both as waveguides and as an optical bench for integration. This allows easy and efficient optical coupling between optical components and optical fibres, removing costly and tedious alignment problems and considerably reducing optical coupling losses in PICs. We expect that the glass-based waveguide PICs technology will enable the emergence of a new generation of compact, reliable, high speed, and multifunctional devices.

Analysis and Characterization of Device Variations in an LSI Chip Using an Integrated Device Matrix Array

For future large-scale integration design technology, the device matrix array (DMA), which precisely evaluates within-die variation in device parameters, has been developed. The DMA consists of a 14-by-14 array of common units. The unit size is 240 by 240 /spl mu/m, and each unit contains 148 measurement elements (52 transistors, 30 capacitors, 51 resistors, and 15 ring oscillators). The element selection and precise measurement are achieved with low parasitic resistance measurement buses and leakage-controlled switching circuits, which allow the measurement accuracy for a transistor, resistor, or capacitor of 90 pA, 11 m/spl Omega/, and 23 aF, respectively, in the 3/spl sigma/ range. The ability to obtain 29 008 samples from a chip enables statistical analysis of the variation in 148 elements of each chip with 240-/spl mu/m spatial resolution. This high resolution and large sample number allows us to precisely decompose the data into systematic and random variation parts with newly developed fourth-order polynomial fitting. Our methodology has been verified using a test chip fabricated by a 130-nm CMOS process with a 100-nm physical gate length and five Cu interconnect layers. In MOSFETs, the random part was dominant and indicated a certain /spl sigma/ value in every chip. In the case of the interconnect layers, the random and systematic parts of the resistance and the capacitance indicated variance fluctuations. By chip, by item, by size, by structure, random or systematic, the /spl sigma/ values of each variation show inconsistency which we believe is attributable to the Cu process. The correlation coefficients of systematic part between device element and ring oscillator frequency shown very high value (0.87-0.98), and those of a random part were low enough (-0.10-0.22) to prove the accuracy of decomposition.

The Design of a Highly Parallel Computer Organization

The design of a computer organization is presented for general-purpose computing with a very high tolerance of failure while taking advantage of future large-scale integration techniques. A high degree of parallel computations may be executed. The organization distributes processing logic along with memory to form cells. The architecture and operation of the cells are developed. Design aspects of the cells are presented along with software considerations of the organization.