2.1 µm multi-quantum well laser epitaxially grown on on-axis (001) InP/SiO/Si substrate fabricated by ion-slicing.

A cost-effective method to achieve a 2-3 µm wavelength light source on silicon represents a major challenge. In this study, we have developed a novel approach that combines an epitaxial growth and the ion-slicing technique. A 2.

High-power, electrically-driven continuous-wave 1.55-μm Si-based multi-quantum well lasers with a wide operating temperature range grown on wafer-scale InP-on-Si (100) heterogeneous substrate.

A reliable, efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics. Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot (QD) lasers, extending the wavelength window to the widely used 1.

Radiation-Hardened and Flexible Pb(ZrTi)O Piezoelectric Sensor for Structural Health Monitoring.

Piezoelectric sensors are excellent damage detectors that can be applied to structural health monitoring (SHM). SHM for complex structures of aerospace vehicles working in harsh conditions is frequently required, posing challenging requirements for a sensor's flexibility, radiation hardness, and high-temperature tolerance. Here, we fabricate a flexible and lightweight Pb(ZrTi)O piezoelectric film on flexible KMg(AlSiO)F substrate via van der Waals (vdW) heteroepitaxy, endowing it with robust ferroelectric and piezoelectric properties under low energy-high flux protons (LE-HFPs) radiation (10 p/cm).

ReS on GaN Photodetector Using H Ion-Cut Technology.

The wafer-scale single-crystal GaN film was transferred from a commercial bulk GaN wafer onto a Si (100) substrate by combining ion-cut and surface-activated bonding. Well-defined, uniformly thick, and large-scale wafer size ReS multilayers were grown on the GaN substrate. Finally, ReS photodetectors were fabricated on GaN and sapphire substrates, respectively, and their performances were compared.

InAs/GaAs quantum dot laser epitaxially grown on on-axis (001) GaAsOI substrate.

Quantum dot (QD) laser as a light source for silicon optical integration has attracted great research attention because of the strategic vision of optical interconnection. In this paper, the communication band InAs QD ridge waveguide lasers were fabricated on GaAs-on-insulator (GaAsOI) substrate by combining ion-slicing technique and molecular beam epitaxy (MBE) growth. On the foundation of optimizing surface treatment processes, the InAs/InGaAs/GaAs dot-in-well (DWELL) lasers monolithically grown on a GaAsOI substrate were realized under pulsed operation at 20 °C.

Thermal Visualization of Buried Interfaces Enabled by Ratio Signal and Steady-State Heating of Time-Domain Thermoreflectance.

Thermal resistances from interfaces impede heat dissipation in micro/nanoscale electronics, especially for high-power electronics. Despite the growing importance of understanding interfacial thermal transport, advanced thermal characterization techniques that can visualize thermal conductance across buried interfaces, especially for nonmetal-nonmetal interfaces, are still under development. This work reports a dual-modulation-frequency time-domain thermoreflectance (TDTR) mapping technique (1.

Thermal Transport across Ion-Cut Monocrystalline β-GaO Thin Films and Bonded β-GaO-SiC Interfaces.

The ultrawide band gap, high breakdown electric field, and large-area affordable substrates make β-GaO promising for applications of next-generation power electronics, while its thermal conductivity is at least 1 order of magnitude lower than other wide/ultrawide band gap semiconductors. To avoid the degradation of device performance and reliability induced by the localized Joule-heating, proper thermal management strategies are essential, especially for high-power high-frequency applications. This work reports a scalable thermal management strategy to heterogeneously integrate wafer-scale monocrystalline β-GaO thin films on high thermal conductivity SiC substrates by the ion-cutting technique and room-temperature surface-activated bonding technique.

Engineering of self-rectifying filamentary resistive switching in LiNbO single crystalline thin film via strain doping.

The abilities to fabricate wafer scale single crystalline oxide thin films on metallic substrates and to locally engineer their resistive switching characteristics not only contribute to the fundamental investigations of the resistive switching mechanism but also promote the practical applications of resistive switching devices. Here, wafer scale LiNbO (LNO) single crystalline thin films are fabricated on Pt/SiO/LNO substrates by ion slicing with wafer bonding. The lattice strain of the LNO single crystalline thin films can be tuned by He implantation as indicated by XRD measurements.

Realization of wafer-scale nanogratings with sub-50 nm period through vacancy epitaxy.

Gratings, one of the most important energy dispersive devices, are the fundamental building blocks for the majority of optical and optoelectronic systems. The grating period is the key parameter that limits the dispersion and resolution of the system. With the rapid development of large X-ray science facilities, gratings with periodicities below 50 nm are in urgent need for the development of ultrahigh-resolution X-ray spectroscopy.

Light-Trapping Engineering for the Enhancements of Broadband and Spectra-Selective Photodetection by Self-Assembled Dielectric Microcavity Arrays.

Light manipulation has drawn great attention in photodetectors towards the specific applications with broadband or spectra-selective enhancement in photo-responsivity or conversion efficiency. In this work, a broadband light regulation was realized in photodetectors with the improved spectra-selective photo-responsivity by the optimally fabricated dielectric microcavity arrays (MCAs) on the top of devices. Both experimental and theoretical results reveal that the light absorption enhancement in the cavities is responsible for the improved sensitivity in the detectors, which originated from the light confinement of the whispering-gallery-mode (WGM) resonances and the subsequent photon coupling into active layer through the leaky modes of resonances.

High-quality factor, high-confinement microring resonators in 4H-silicon carbide-on-insulator.

Silicon carbide (SiC) exhibits promising material properties for nonlinear integrated optics. We report on a SiC-on-insulator platform based on crystalline 4H-SiC and demonstrate high-confinement SiC microring resonators with sub-micron waveguide cross-sectional dimensions. The Q factor of SiC microring resonators in such a sub-micron waveguide dimension is improved by a factor of six after surface roughness reduction by applying a wet oxidation process.

Efficient ion-slicing of InP thin film for Si-based hetero-integration.

Integration of high quality single crystalline InP thin film on Si substrate has potential applications in Si-based photonics and high-speed electronics. In this work, the exfoliation of a 634 nm crystalline InP layer from the bulk substrate was achieved by sequential implantation of He ions and H ions at room temperature. It was found that the sequence of He and H ion implantations has a decisive influence on the InP surface blistering and exfoliation, which only occur in the InP pre-implanted with He ions.

Investigation on thermodynamics of ion-slicing of GaN and heterogeneously integrating high-quality GaN films on CMOS compatible Si(100) substrates.

Die-to-wafer heterogeneous integration of single-crystalline GaN film with CMOS compatible Si(100) substrate using the ion-cutting technique has been demonstrated. The thermodynamics of GaN surface blistering is in-situ investigated via a thermal-stage optical microscopy, which indicates that the large activation energy (2.5 eV) and low H ions utilization ratio (~6%) might result in the extremely high H fluence required for the ion-slicing of GaN.

Plasma-Induced Nonvolatile Resistive Switching with Extremely Low SET Voltage in TiOF with AgF Nanoparticles.

Low power consumption is crucial for the application of resistive random access memory. In this work, we present the bipolar resistive switching in an Ag/TiOF/Ti/Pt stack with extremely low switch-on voltage of 0.07 V.

Engineering interface-type resistive switching in BiFeO3 thin film switches by Ti implantation of bottom electrodes.

BiFeO3 based MIM structures with Ti-implanted Pt bottom electrodes and Au top electrodes have been fabricated on Sapphire substrates. The resulting metal-insulator-metal (MIM) structures show bipolar resistive switching without an electroforming process. It is evidenced that during the BiFeO3 thin film growth Ti diffuses into the BiFeO3 layer.

Single pairing spike-timing dependent plasticity in BiFeO3 memristors with a time window of 25 ms to 125 μs.

Memristive devices are popular among neuromorphic engineers for their ability to emulate forms of spike-driven synaptic plasticity by applying specific voltage and current waveforms at their two terminals. In this paper, we investigate spike-timing dependent plasticity (STDP) with a single pairing of one presynaptic voltage spike and one post-synaptic voltage spike in a BiFeO3 memristive device. In most memristive materials the learning window is primarily a function of the material characteristics and not of the applied waveform.

Bipolar electric-field enhanced trapping and detrapping of mobile donors in BiFeO3 memristors.

Pulsed laser deposited Au-BFO-Pt/Ti/Sapphire MIM structures offer excellent bipolar resistive switching performance, including electroforming free, long retention time at 358 K, and highly stable endurance. Here we develop a model on modifiable Schottky barrier heights and elucidate the physical origin underlying resistive switching in BiFeO3 memristors containing mobile oxygen vacancies. Increased switching speed is possible by applying a large amplitude writing pulse as the resistive switching is tunable by both the amplitude and length of the writing pulse.

Preparation and growth mechanism of chrysanthemum-like ZnO nanowire clusters.

With sodium hydroxide (NaOH), ammonia water (NH3 x H2O) and hexamethylenetetramine (HMT, C6H12N4) respectively as alkaline source material, a simple hydrothermal process was employed to prepare chrysanthemum-like ZnO nanowire clusters. The morphologies and crystalline structures of the as-prepared products were investigated by X-ray diffractometer (XRD), field emission environment scanning electron microscope (SEM), and high-resolution transmission electron microscopy (TEM). The experimental results indicate that the as-prepared products all have three-dimensional chrysanthemum-like structure in which the petal-like nanowires are ZnO single crystalline with hexagonal wurtzite structure, that the flower bud saturation degree F(d) is slightly different under different alkaline source materials, and that the proposed growth mechanism of chrysanthemum-like ZnO nanowire clusters is reasonable.