Semiconductor Membrane Research Articles

III-nitride semiconductor membrane electronics and optoelectronics for heterogeneous integration

III-nitride semiconductor membrane electronics and optoelectronics for heterogeneous integration

Remote epitaxy and freestanding wide bandgap semiconductor membrane technology

Remote epitaxy and freestanding wide bandgap semiconductor membrane technology

Multitype Quantum Well Semiconductor Membrane External-Cavity Surface-Emitting Lasers for Widely Tunable Continuous Wave Operation.

Membrane external-cavity surface-emitting lasers (MECSELs) represent a cutting-edge approach in pushing the performance boundaries of vertically emitting semiconductor lasers. The fundamental concept of employing an extremely thin gain membrane, spanning from hundreds of nanometers to a few micrometers in thickness and sandwiched between transparent heat spreaders, introduces novel opportunities through uniform double-sided optical pumping and enhanced heat dissipation from the active region. Additionally, these advantages of MECSELs facilitate more intricate band gap engineering possibilities for the active region by integrating multiple types of quantum wells (QWs) into a single laser gain structure. This work introduces a novel design strategy for laser gain structures incorporating various QW types. The objective is to achieve broad-spectrum gain with relatively high-power operation and potentially a flat spectral tuning range. Our design focuses on ensuring sufficient gain across a wide wavelength span, achieving uniform pump absorption, and limiting carrier mobility between different quantum well types during laser operation. We demonstrate a full-width half-maximum (FWHM) tuning range exceeding 70 nm (equivalent to more than 21.7 THz) with over 125 mW of output power across this entire tuning range at room temperature.

Semiconductor Membrane Exfoliation: Technology and Application

AbstractFlexible semiconductor film‐based optoelectronic devices have garnered significant attention in emerging fields such as the Internet of Things (IoT), wearable devices, and smart healthcare due to their wide range of applications. It is challenging to directly grow the foundational materials of optoelectronic devices, specifically semiconductor thin film structures, on flexible substrates. Instead, they are typically fabricated on conventional rigid thick semiconductor substrates. Consequently, the exfoliation and transfer of epitaxial semiconductor thin film structures onto substrates constitute pivotal steps in the production of flexible optoelectronic devices. The integration of hard inorganic semiconductor materials with flexible substrates offers a solution to the limitations of rigidity and brittleness associated with conventional optoelectronic devices and can be used to address challenges from design to manufacturing. This review provides a comprehensive overview of the working principles and recent advances of various techniques aimed at achieving the membrane exfoliation and transfer of semiconductor structures on conventional rigid substrates. It also reviews the possible applications of the transferred membrane in a variety of optoelectronic devices. Finally, it offers insights into the potential of high‐end semiconductor manufacturing and flexible semiconductor devices to play a critical role in advancing next‐generation optoelectronics technologies.

Dynamic and controlled stretching of macroscopic crystalline membranes towards unprecedented levels

Imposing and controlling strain in materials such as semiconductors or ferroelectrics is a promising way to obtain new or enhance existing properties. Although the field of strain engineering has seen a rapid expansion over the last two decades, straining semiconductor membranes over large areas remains a challenge. A generic way of tuning strain and hence band structure and electric or magnetic properties of any crystalline material can be obtained by compression of a composite structure involving poorly compressible elastomers. Mechanically similar to the principle of a hydraulic press, this work proposes a device and describes analytically a methodology to easily strain macroscopic membranes up to unprecedented values. Using in-situ X-ray diffraction and Raman spectroscopy, we tuned the biaxial strain in silicon membranes up to a value of 2.1 %, paving the way for new studies in the field of strain related physics, from semiconductors to perovskite oxide multiferroics.

Dual-Use Strain Sensors for Acoustic Emission and Quasi-Static Bending Measurements.

In this paper, a MEMS piezoresistive ultrathin silicon membrane-based strain sensor is presented. The sensor's ability to capture an acoustic emission signal is demonstrated using a Hsu-Nielsen source, and shows comparable frequency content to a commercial piezoceramic ultrasonic transducer. To the authors' knowledge, this makes the developed sensor the first known piezoresistive strain sensor which is capable of recording low-energy acoustic emissions. The improvements to the nondestructive evaluation and structural health monitoring arise from the sensor's low minimum detectable strain and wide-frequency bandwidth, which are generated from the improved fabrication process that permits crystalline semiconductor membranes and advanced polymers to be co-processed, thus enabling a dual-use application of both acoustic emission and static strain sensing. The sensor's ability to document quasi-static bending is also demonstrated and compared with an ultrasonic transducer, which provides no significant response. This dual-use application is proposed to effectively combine the uses of both strain and ultrasonic transducer sensor types within one sensor, making it a novel and useful method for nondestructive evaluations. The potential benefits include an enhanced sensitivity, a reduced sensor size, a lower cost, and a reduced instrumentation complexity.

Recent advancement of solid oxide fuel cells towards semiconductor membrane fuel cells

In the last few decades, there has been remarkable progress in the development of solid oxide fuel cells (SOFCs) based on both traditional solid electrolyte materials and novel semiconductor membranes. However, limited attention has been given to the transition of SOFCs from oxide ion-based electrolyte membranes to semiconductor membrane devices, considering the overall perspective of materials, technology, and scientific principles. Traditional knowledge strictly dictates that semiconductors should not be used as the membrane unless these materials possess negligible electronic conduction. This is because semiconductor membrane materials typically exhibit significantly higher electrical conductivity, surpassing the inherent ionic conductivity. Interestingly, by using semiconductors as the membrane, numerous novel materials have been demonstrated in the literature, which seems difficult to understand from traditional SOFC knowledge. Therefore, there is an emerging need to summarize and explore new understanding and knowledge of materials, technology, and science of SOFCs and Semiconductor Membrane Fuel Cells and their transition. In this review, we attempted to summarize the gap between the current state of SOFCs and the advancements in new materials, technologies, scientific principles, and mechanisms driving the development of such devices.

Universal design method for bright quantum light sources based on circular Bragg grating cavities.

We theoretically develop an efficient and universal design scheme of quantum light sources based on hybrid circular Bragg grating (CBG) cavity with and without electrical contact bridges. As the proposed design scheme strongly alleviates the computational cost of numerical simulation, we present high-performance CBG designs based on the GaAs/SiO2/Au material system for emission wavelengths ranging from 900 nm to 1600 nm, covering the whole telecom O-band and C-band. All designs achieve remarkable Purcell factors surpassing a value of 26 and extraction efficiencies (into a numerical aperture of 0.8) exceeding 92% without contact bridges and 86% with contact bridges. Additionally, we show that our design approach easily deals with realistic structural constraints, such as preset thicknesses of a semiconductor membrane or SiO2 layers or with a different material system. The high design flexibility greatly supports the experimental deterministic fabrication approaches, allowing one to perform in-situ design adaptation and to integrate single quantum emitters of an inhomogeneously broadened ensemble on the same chip into wavelength-adapted structures without spectral constraints, which highly increase the yield of quantum device fabrication.

Effect of Non-Resonant Gain Structure Design in Membrane External-Cavity Surface-Emitting Lasers

The operation of a semiconductor membrane external-cavity surface-emitting laser (MECSEL) employing a gain membrane with a cavity design, which is non-resonant regarding the two semiconductor - heat-spreader interfaces, is presented. The MECSEL delivers watt-level output power, in line with state-of-the-art results. The study provides new evidence that the design criteria of a MECSEL gain region are significantly relaxed compared to active regions employing distributed Bragg reflectors, for which the field distribution is set by the Bragg condition leading to tight tolerances for positioning of the emitting quantum structures. The study has relevance especially for the development of mode-locked MECSELs by minimizing the impact of defective Fabry-Pérot micro-cavity effects due to reflections between the semiconductor gain structure and the two heat-spreader elements placed on each side of the semiconductor membrane.

Heterogeneous integration of superconducting thin films and epitaxial semiconductor heterostructures with lithium niobate

We report on scalable heterointegration of superconducting electrodes and epitaxial semiconductor quantum dots (QDs) on strong piezoelectric and optically nonlinear lithium niobate. The implemented processes combine the sputter-deposited thin film superconductor niobium nitride and III–V compound semiconductor membranes onto the host substrate. The superconducting thin film is employed as a zero-resistivity electrode material for a surface acoustic wave resonator with internal quality factors representing a three-fold enhancement compared to identical devices with normal conducting electrodes. Superconducting operation of resonators is achieved to temperatures and electrical radio frequency powers . Heterogeneously integrated single QDs couple to the resonant phononic field of the surface acoustic wave resonator operated in the superconducting regime. Position and frequency selective coupling mediated by deformation potential coupling is validated using time-integrated and time-resolved optical spectroscopy. Furthermore, acoustoelectric charge state control is achieved in a modified device geometry harnessing large piezoelectric fields inside the resonator. The hybrid QD—surface acoustic wave resonator can be scaled to higher operation frequencies and smaller mode volumes for quantum phase modulation and transduction between photons and phonons via the QD. Finally, the employed materials allow for the realization of other types of optoelectronic devices, including superconducting single photon detectors and integrated photonic and phononic circuits.

High-throughput manufacturing of epitaxial membranes from a single wafer by 2D materials-based layer transfer process

Layer transfer techniques have been extensively explored for semiconductor device fabrication as a path to reduce costs and to form heterogeneously integrated devices. These techniques entail isolating epitaxial layers from an expensive donor wafer to form freestanding membranes. However, current layer transfer processes are still low-throughput and too expensive to be commercially suitable. Here we report a high-throughput layer transfer technique that can produce multiple compound semiconductor membranes from a single wafer. We directly grow two-dimensional (2D) materials on III-N and III-V substrates using epitaxy tools, which enables a scheme comprised of multiple alternating layers of 2D materials and epilayers that can be formed by a single growth run. Each epilayer in the multistack structure is then harvested by layer-by-layer mechanical exfoliation, producing multiple freestanding membranes from a single wafer without involving time-consuming processes such as sacrificial layer etching or wafer polishing. Moreover, atomic-precision exfoliation at the 2D interface allows for the recycling of the wafers for subsequent membrane production, with the potential for greatly reducing the manufacturing cost.

Au-doped ZnO@ZIF-7 core-shell nanorod arrays for highly sensitive and selective NO2 detection

The exploration of novel NO2 sensors with high performance is of great importance for air quality monitoring and human health. In this work, Au-doped ZnO@ZIF-7 core-shell nanorod arrays were fabricated for high-performance NO2 detection. Due to the spill-over effects of Au nanoparticles, gas enriching and molecular sieving effects provided by ZIF-7 membranes, the ZnO-Au@ZIF-7 sensor affords highly sensitive and selective detection of NO2. The heterostructured ZnO-Au@ZIF-7 allows for ppb-level detection of NO2 (Response = 1.7–5 ppb) with excellent repeatability and provides improved selectivity, anti-humidity capacity, and long-term stability compared with bare ZnO, Au-doped ZnO or ZnO@ZIF-7 core-shell nanorod arrays. According to the calculation of density functional theory (DFT), the ZnO-Au@ZIF-7 sensor renders higher adsorption energy towards NO2 molecules compared with the aforementioned other materials, which also explains its outstanding sensing performances. We believe our approach that combines noble metals doped semiconductor metal oxides (SMOs) and MOF filtration membranes can be further extended to numerous new heterostructured SMO@MOF materials, which opens venues to the development of advanced chemiresistive gas sensors.

Strain relaxation of semiconductor membranes: insights from finite element modeling

Finite element (FE) models were employed to better understand the process used to fabricate elastically strain-relaxed in-place bonded semiconductor membranes for application as engineered substrates for semiconductor devices (Cohen et al 2005 Appl. Phys. Lett. 86 251902; Owen et al 2008 ECS Trans. 16 271; Owen et al 2009 Sci. Technol. 24 035011; Mooney et al 2014 Semicond. Sci. Technol. 29 075009; Salehzadeh et al 2014 Semicond. Sci. Technol. 29 085002). Initial structures consist of a compressively strained, square semiconductor membrane atop a sacrificial layer that is subsequently removed by etching in an hydrofluoric acid (HF) solution. Elastic relaxation of the compressive strain bends the free area of the membrane toward the substrate. But for the dimensions of most of the structures employed in the fabrication of in-place bonded membranes, the bending by elastic strain relaxation alone is not sufficient for the membrane corners to contact the substrate. FE models, therefore, confirm that an attractive force between the surface of the membrane and the surface of the substrate in the HF solution must act to hold the membrane in place during the wet etching process. FE models also confirm that in the etch solution the interface between the membrane and the substrate must be a sliding interface in order for the membrane to lie flat on the substrate once the sacrificial layer has been completely removed.

Processive Pathways to Metastability in Block Copolymer Thin Films.

Block copolymers (BCPs) self-assemble into intricate nanostructures that enhance a multitude of advanced applications in semiconductor processing, membrane science, nanopatterned coatings, nanocomposites, and battery research. Kinetics and thermodynamics of self-assembly are crucial considerations in controlling the nanostructure of BCP thin films. The equilibrium structure is governed by a molecular architecture and the chemistry of its repeat units. An enormous library of materials has been synthesized and they naturally produce a rich equilibrium phase diagram. Non-equilibrium phases could potentially broaden the structural diversity of BCPs and relax the synthetic burden of creating new molecules. Furthermore, the reliance on synthesis could be complicated by the scalability and the materials compatibility. Non-equilibrium phases in BCPs, however, are less explored, likely due to the challenges in stabilizing the metastable structures. Over the past few decades, a variety of processing techniques were introduced that influence the phase transformation of BCPs to achieve a wide range of morphologies. Nonetheless, there is a knowledge gap on how different processive pathways can induce and control the non-equilibrium phases in BCP thin films. In this review, we focus on different solvent-induced and thermally induced processive pathways, and their potential to control the non-equilibrium phases with regards to their unique aspects and advantages. Furthermore, we elucidate the limitations of these pathways and discuss the potential avenues for future investigations.

Structural optimization and simulation of piezoelectric- piezoresistive coupled MEMS steady-state electric field sensor

Abstract: In view of the problems of large volume, high energy consumption and difficult maintenance of electric field measurement sensors in existing power systems, non-contact miniature electric field sensors have become a hot topic in current research. In this paper, a MEMS miniature electric field measurement sensor model based on the principle of piezoelectric-piezoresistive coupling is constructed, and the sensor structure is optimized by analyzing the steady-state characteristics of the piezoelectric material and semiconductor membrane of the sensor. The input and output characteristics of the sensor were tested. The test results show that the sensor has excellent mechanical strain capacity, and the output voltage of the sensor has a linear relationship with the electric field strength, thus verifying the feasibility of the sensor measurement in the electric field. The research results will provide some reference for the development of contactless coupled sensors.

Large-Scale Silver Sulfide Nanomesh Membranes with Ultrahigh Flexibility.

The growth of flexible semiconductor thin films and membranes is highly desirable for the fabrication of next-generation wearable devices. In this work, we have developed a one-step, surface tension-driven method for facile and scalable growth of silver sulfide (Ag2S) membranes with a nanomesh structure. The nanomesh membrane can in principle reach infinite size but only limited by the reactor size, while the thickness is self-limited to ca. 50 nm. In particular, the membrane can be continuously regenerated at the water surface after being transferred for mechanical and electronic tests. The free-standing membrane demonstrates exceptional flexibility and strength, resulting from the nanomesh structure and the intrinsic plasticity of the Ag2S ligaments, as revealed by robust manipulation, nanoindentation tests and a pseudo-in situ tensile test under scanning electron microscope. Bendable electronic resistance-switching devices are fabricated based on the nanomesh membrane.

2D materials-assisted heterogeneous integration of semiconductor membranes toward functional devices

Heterogeneous integration techniques allow the coupling of highly lattice-mismatched solid-state membranes, including semiconductors, oxides, and two-dimensional materials, to synergistically fuse the functionalities. The formation of heterostructures generally requires two processes: the combination of crystalline growth and a non-destructive lift-off/transfer process enables the formation of high-quality heterostructures. Although direct atomic interaction between the substrate and the target membrane ensures high-quality growth, the strong atomic bonds at the substrate/epitaxial film interface hinder the non-destructive separation of the target membrane from the substrate. Alternatively, a 2D material-coated compound semiconductor substrate can transfer the weakened (but still effective) surface potential field of the surface through the 2D material, allowing both high-quality epitaxial growth and non-destructive lift-off of the grown film. This Perspective reviews 2D/3D heterogeneous integration techniques, along with applications of III–V compound semiconductors and oxides. The advanced heterogeneous integration methods offer an effective method to produce various freestanding membranes for stackable heterostructures with unique functionalities that can be applied to novel electrical, optoelectronic, neuromorphic, and bioelectronic systems.

Hybrid membrane-external-cavity surface-emitting laser.

We develop, analyze, and demonstrate an optically-pumped semiconductor disk laser using an active mirror architecture formed by sandwiching the semiconductor gain membrane between two heatspreaders, one of which is coated with a high-reflectivity multilayer. Thermal modeling indicates that this structure outperforms traditional VECSELs. Employing an InGaAs/GaAs MQW gain structure, we demonstrate output powers of approximately 30 W at a center wavelength of λ ≈ 1178 nm in a TEM00 mode using an in-well pumped geometry.

Optical ReLU using membrane lasers for an all-optical neural network.

In this study, we propose low power consumption, programmable on-chip optical nonlinear units (ONUs) for all-optical neural networks (all-ONNs). The proposed units were constructed using a III-V semiconductor membrane laser, and the nonlinearity of the laser was used as the activation function of a rectified linear unit (ReLU). By measuring the relationship of the output power and input light, we succeeded in obtaining the response as an activation function of the ReLU with low power consumption. With its low-power operation and high compatibility with silicon photonics, we believe that this is a very promising device for realizing the ReLU function in optical circuits.

Built-in Electric Field for Efficient Charge Separation and Ionic Transport in LiCoO2/SnO2 Semiconductor Junction Fuel Cells

Built-in electric field (BIEF)-induced charge transfer in planar and bulk junctions has significantly improved electrochemical performance in current and advanced energy storage devices such as lithium, sodium, and aluminum batteries. In this study, fuel cells with different junctions based on semiconductor membranes were designed in thin-film planar, bulk planar, and bulk heterojunction (BHJ) configurations to investigate the BIEF effects on their electrochemical performance. These semiconductor membrane fuel cells were constructed with p-type LiCoO2 and n-type SnO2 sandwiched between Ni0.8Co0.15Al0.05LiO2 (NCAL) electrode semiconductors. At 600 °C, the fuel cells with bulk heterojunction (BHJ), bulk planar p–n junction, and thin-film planar p–n junction deliver remarkable peak power densities of 0.82, 0.61, and 0.28 W/cm2 in H2/air operation, respectively. The band structures were determined and the charge transport properties and device operation were investigated. Our results show that the semiconductor membrane-based devices are a good alternative to replace the conventional electrolyte membrane fuel cells for the next generation of fuel-to-electricity conversion technology.