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We demonstrate industry’s first 300 mm GaN transistor technology and 3-D monolithic heterogeneous integration with Si transistors, enabled by 300 mm GaN metal–organic chemical vapor deposition (MOCVD) epitaxy and 300 mm 3-D layer transfer. The 300 mm GaN technology is a high- ${k}$ dielectric enhancement-mode GaN nMOS transistor technology on Si(111) substrate. It is capable of excellent characteristics and figure-of-merits (FOM) for realizing energy-efficient, compact power-delivery and RF front-end components such as power-amplifiers, low-noise amplifiers, and RF-switches. Our GaN nMOS transistors show e-mode operation with: 1) high ${I}_{\text {D,max}} =1.5$ mA/ $\mu \text{m}$ ; 2) low ${R}_{ \mathrm{\scriptscriptstyle ON}}$ of $610\,\,\Omega -\mu \text{m}$ ( ${L}_{\text {G}} =50$ nm); 3) low ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ of 100 pA/ $\mu \text{m}$ ( ${L}_{\text {G}} \,\,=180$ nm), which are significant improvements over GaN HEMT; 4) excellent RF performance: ${f}_{\text {T}} =190$ GHz, ${f}_{\text {MAX}} =300$ GHz, power-added efficiency (PAE) = 56% ( ${L}_{\text {G}} \,\,=50$ nm) at mmwave frequency 28 GHz, and PAE = 77% at 5 GHz ( ${L}_{\text {G}} =180$ nm), significantly better than industry-standard GaAs and Si RF transistors; 5) good RF-switch FOM, ${R}_{ \mathrm{\scriptscriptstyle ON}}{C}_{ \mathrm{\scriptscriptstyle OFF}} =110$ fs; and 6) low noise figure, NF $_{\text {min}} \,\,=1.36$ dB ( ${f} =28$ GHz) and 0.4 dB ( ${f} =5$ GHz), all at SoC-compatible voltages. We further demonstrate GaN transistor innovations all integrated on 300 mm Si(111) wafer, including depletion-mode GaN nMOS transistor with high ${I}_{\text {D}} =1.8$ mA/ $\mu \text{m}$ ; GaN Schottky gate transistor producing high saturated power of 20 dBm ( $80\mu \text{m}$ width) with peak PAE = 57% at 28 GHz; low leakage compact cascode and multigate GaN transistors; and GaN Schottky diodes with ultralow ${C}_{ \mathrm{\scriptscriptstyle OFF}}$ for electrostatic discharge (ESD) protection. The layer-transferred Si transistors, monolithically stacked on top of the GaN transistors by 300 mm 3-D layer transfer, show high drive current performance: 1.0 mA/ $\mu \text{m}$ (Si nMOS) and 0.5 mA/ $\mu \text{m}$ (Si pMOS). Such a monolithic 3-D Monolithic integration of GaN and Si transistors enables full integration of energy-efficient, truly compact power delivery and RF solutions with CMOS digital signal processing, logic computation and control, memory, and analog circuitries.

We demonstrate 3-D self-aligned stacked NMOS-on-PMOS multiple Si nanoribbon transistors with successful integration of vertically stacked dual source/drain EPI process and vertically stacked dual metal gate process. Both top NMOS and bottom PMOS show high on-state performance and superior short channel control. A functional CMOS inverter is also demonstrated with well-balanced voltage transfer characteristics. The 3-D self-aligned stacked CMOS nanoribbon transistor is demonstrated as a promising transistor architecture to continue Moore’s law scaling.

We discuss advances in our research on 300mm GaN NMOS by demonstrating GaN-on-Si(111) NMOS transistors achieving low R ON =330Ω-μm; high ID,max=1.7mA/μm; BV DS (at I D =1μA/μm) of up to 90V with excellent R ON =660Ω-μm; record f T /f MAX of 200/350GHz for GaN-on-Si; industry’s best RF switch R on C off =55fs; and highest mmwave (28GHz) RF power amplifier peak PAE of 65% @ 19.5dBm saturated power. We discuss and compare the challenges in approaches to GaN and Si CMOS integration research including: (a) poly-silicon CMOS, (b) heterogeneous epitaxy of GaN and Si(111) CMOS, (c) wafer-to-wafer bonding [2], and (d) 3D monolithic Si(100) layer transfer using bonding techniques [1],[3].

We expand on our work in [1] by demonstrating both Si P- and NMOS finfet transistors monolithically integrated with GaN transistors on 300mm Si(111) wafers using 3D integration. With the Si finfet architecture, we are able to take advantage of the fin orientations of the transferred Si(100) crystal to fabricate both high performance Si P- and NMOS transistors. Furthermore, we demonstrate a variety of GaN transistor innovations, including enhancement (e-mode) and depletion mode (d-mode) GaN NMOS transistor with high $\mathrm{I}_{\mathrm{D}}=1.8\mathrm{m}_{1}\mathrm{W}\mu \mathrm{m};\mathrm{GaN}$ Schottky gate transistor producing high saturated power of 20dBm with peak PAE=57% at 28GHz; high performing, low leakage cascode and multi-gate GaN transistors; and GaN Schottky diodes with ultra-low $\mathrm{C}_{\mathrm{OFF}}$ for ESD protection, all integrated on 300mm Si(111) wafer.

We have demonstrated industry’s first 300mm 3D heterogeneous integration of high performance, low-leakage high-K dielectric metal gate enhancement-mode (e-mode) GaN NMOS and Si PMOS transistors on 300mm high-resistivity (HR) Si(111) substrate, enabled by 300mm GaN MOCVD epitaxy and 300mm 3D layer transfer. The fabricated (bottom device layer) high-K dielectric e-mode GaN NMOS transistors, integrated on a 300mm HR Si(111) substrate, show excellent electrical characteristics and figure-of-merits (FOM) for realizing energy-efficient, compact voltage regulators and RF front-end components such as power amplifiers, low-noise amplifiers and RF switches, with (i) I OFF as low as 100pA/μm (V D =5V, V G =0V), (ii) high I D,max =1.5mA/μm; (iii) R ON as low as 610Ω-μm, significantly better than industry-standard Si transistors at equivalent drain breakdown (BV D ), (iv) excellent RF performance: f T =190GHz, f MAX =300GHz, PAE=56% at mmwave frequency (f=28GHz), and PAE=70% at sub-7GHz (f=5GHz), significantly better than industry-standard GaAs and Si RF transistors, (v) excellent RF switch FOM, R on C off =110fs, and (vi) low noise figure, NF min =1.36dB (f=28GHz), 0.4dB (f=5GHz) and 0.27dB (f=1.8GHz), all at SoC-compatible voltages. The fabricated (top device layer) L G =65nm and 130nm Si PMOS transistors, which are monolithically integrated on top of the bottom GaN NMOS transistors by 300mm 3D layer transfer, show respectively, high drive current of 0.85mA/μm, and low I off of 150pA/μm at V D =-1.2V. Such a monolithic 3D integration of GaN NMOS and Si PMOS enables full integration of energy-efficient, truly compact power delivery and RF solutions with CMOS digital signal processing, logic computation and control, memory functions and analog circuitries for next generation power delivery, RF (5G and beyond) and SoC applications.

We investigate the structural and quantum transport properties of isotopically enriched Si28/SiO228 stacks deposited on 300-mm Si wafers in an industrial CMOS fab. Highly uniform films are obtained with an isotopic purity greater than 99.92%. Hall-bar transistors with an oxide stack comprising 10 nm of Si28O2 and 17 nm of Al2O3 (equivalent oxide thickness of 17 nm) are fabricated in an academic cleanroom. A critical density for conduction of 1.75×1011cm-2 and a peak mobility of 9800cm2/Vs are measured at a temperature of 1.7 K. The Si28/SiO228 interface is characterized by a roughness of Δ=0.4nm and a correlation length of Λ=3.4nm. An upper bound for valley splitting energy of 480μeV is estimated at an effective electric field of 9.5 MV/m. These results support the use of wafer-scale Si28/SiO228 as a promising material platform to manufacture industrial spin qubits.

Motivated by theoretical predictions that spatially complex concentration modulations of Si and Ge can increase the valley splitting in quantum wells, we grow and characterize Si/SiGe heterostructures with a thin, pure Ge layer at the top of the quantum well using chemical vapor deposition. We show that these heterostructures remain hosts for high-mobility electron gases. We measure two quantum wells with approximately five monolayers of pure Ge at the upper barrier, finding mobilities as high as 70,000 cm$^2$/Vs, compared to 100,000 cm$^2$/Vs measured in samples with no Ge layer. Activation energy measurements in quantum Hall states corresponding to Fermi levels in the gap between different valley states reveal energy gaps ranging from 30 to over 200 $\mu$eV, and we extract a surprisingly strong dependence of the energy gap on electron density. We interpret our results using tight binding theory and argue that our results are evidence that atomic scale disorder at the quantum well interface dominates the behavior of the valley splittings of these modified heterostructures., Comment: 7 pages

The tear film is a valuable diagnostic fluid for a continuous, minimally invasive surveillance of health conditions in a patient. We developed an electronic enzymatic l -lactate sensor on a polymer substrate molded into contact lens shape for potential in situ monitoring of l -lactate levels in tear fluid. The platinum sensing structures were functionalized by cross-linkage of lactate oxidase with glutaraldehyde and bovine serum albumin, and coated with medical grade polyurethane. Different approaches for the suppression of interfering species present in the tear film were evaluated. The sensors show a quick response time of 35 s, an average sensitivity of ∼53 μA mM −1 cm −2 within their linear range, and sufficient resolution within the physiological range of lactate concentrations. A dual sensor design was found appropriate for the suppression of interfering signals. The sensors are functional at temperatures comparable to those at the surface of the eye, and their response is stable for up to 24 h.

We demonstrate the direct immobilization of glucose oxidase and lactate oxidase onto photoresists commonly used in microfabrication. The method allows for a cost-effective, facile inclusion of enzyme functionality into novel MEMS devices because it does not require any chemical or physical pre-treatment of surfaces, and it is largely compatible with existing fabrication technologies. We used fluorescence imaging and absorbance spectrometry to confirm attachment of the enzymes onto the photoresists and to determine their activity. In addition, the procedure was used to successfully integrate enzyme functionality into a photoresist-based biosensor. This further demonstrates the effectiveness of the approach, and opens a path towards other novel applications in MEMS research.

A large population of carbon nanotube field effect transistors (CNT-FETs), including a variety of channel morphologies with single and multiple tubes, was electrically characterized in atmospheric, ultra-high vacuum (UHV) and oxygen-rich environments. Devices were systematically classified according to the number and nature of the bridging CNTs based on a rigorous device characterization methodology. A statistical analysis of the interaction of oxygen with such a complex population of devices reveals shifts in carrier type, contact resistance and threshold voltages indicative of both charge trapping and transport barrier modulation at the tube–electrode interface. Devices with a single semiconducting tube could be changed from p-type (hole conduction) at atmosphere to n-type (electron conduction) through vacuum-annealing. Furthermore, the average resistance of these CNT-FETs after annealing was observed to decrease from 2.16 MΩ under UHV to 1.0 MΩ in the presence of pure oxygen while threshold voltages shifted from −5.5 V to −2.2 V. Overall responses to ambient conditions is dependent on the device morphology as well as the use of thermal annealing.

We report here an effective method for the fabrication of a large number of triode-type microgated carbon nanotube field emitter arrays. Our technique combines dual-beam focused ion beam technology and plasma-enhanced chemical vapor deposition, avoiding the tedious lithography and wet chemistry procedures conventionally used to fabricate such structures. Field emission testing revealed that increasing gate voltage by as little as 0.3 V had significant impact on the local electric fields, lowering the turn on and threshold fields by 3.6 and 3.0 V/microm, respectively. The field enhancement factor of the emitter arrays was also increased from 149 to 222. A quantum mechanical model for such triode-type field emission indicates that the local electric field generated by a negatively or positively biased gate directly impacts the tunneling barrier thickness and thus the achievable emitter current.

The effect of electrode work function (WF) on the device resistance of carbon-nanotube field-effect transistors (CNT-FETs) is less significant than that of device surface chemistry, specifically interactions with molecular oxygen adsorbate. Experimental results are based on over 130 individual devices with electrode WFs varying from 4.17 to 5.21 eV that were tested under standard-atmosphere, ultrahigh-vacuum, and pure-oxygen environments. Oxygen decreased device resistance by an average of 56% and altered majority charge carriers regardless of electrode metal. Variations in CNT-FET performance based on electrode material appeared more closely associated with crystallization and oxidation states than WF.

Nitrogen-vacancy (NV) centers coupled to scalable optical networks have the potential to realize solid-state quantum information processing platforms. Toward this goal, we demonstrate coupling of near-surface NV- centers to an array of GaP optical resonators. The use of GaP as the optical waveguiding materials is appealing due to the possibility of realizing integrated photonic switches based on the linear electro-optic effect. We explore large-area integration of GaP on diamond through two routes: molecular beam deposition directly onto diamond substrates and layer transfer of single-crystalline sheets. While the direct deposition benefits from simpler, monolithic processing, the layer transfer route benefits from higher material quality. In the latter approach, we demonstrate the transfer of submicrometer thick, mm2-sized GaP sheets from a GaP/AlGaP/GaP substrate to a diamond sample prepared with near-surface NV- centers. We fabricate large arrays of GaP disk resonators with varying diameters (1 to 20 μm) on the diamond substrate via electron beam lithography and dry etching, and show coupling of the NV- center emission to the cavity structures. Quality factors above 10,000 were observed in 5 μm diameter disks on the non-etched diamond substrate. Similar quality factors in smaller sized devices are expected with diamond substrate etching to further confine the optical mode. This approach opens a path towards the integration of coupled optical components in the hybrid GaP/diamond system, an essential step towards large-scale photonic networks utilizing NV- centers in diamond.

Large-scale entanglement of nitrogen-vacancy (NV) centers in diamond will require integration of NV centers with optical networks. Toward this goal, we present the fabrication of single-crystalline gallium phosphide (GaP) resonator-waveguide coupled structures on diamond. We demonstrate coupling between 1 {\mu}m diameter GaP disk resonators and waveguides with a loaded Q factor of 3,800, and evaluate their potential for efficient photon collection if integrated with single photon emitters. This work opens a path toward scalable NV entanglement in the hybrid GaP/diamond platform, with the potential to integrate on-chip photon collection, switching, and detection for applications in quantum information processing., Comment: 9 pages, 5 figures, submitted to Optics Express

Loss measurements at a wavelength of 632 nm are presented for optical waveguides fabricated in polycrystalline GaP grown directly on SiO2. Devices fabricated in poly-GaP on diamond are also shown.

We present the fabrication and electrochemical characterization of an electronic molecular lactate sensor comprised of an optimized three-electrode setup on a transparent, flexible polymer substrate. The sensors are functionalized with the flavoenzyme lactate oxidase as a selective, nanoscale recognition element. They exhibit an exceptionally high sensitivity in their linear range of ∼ 370 µAmM−1cm−2, a very low detection limit of ∼ 5 µM, and good thermal stability, with a working electrode area of only ∼ 0.19 mm2. We envision the sensors being utilized for one-time measurements of lactate levels in food or agricultural products for monitoring of their freshness, and show results of lactate level measurements for various dairy products.

We demonstrate the use of common photoresists for the direct immobilization of enzymes on micropatterns. Absorbance spectrometry and fluorescence imaging confirmed successful attachment of glucose oxidase on both positive and negative resists commonly used in the microfabrication of MEMS. For SU8, the immobilization may be, at least partially, caused by covalent binding of the enzyme to the substrate mediated by amine groups. Since no pre-treatment of the substrate is needed for the attachment, the proposed method allows for a facile and very versatile approach for the integration of enzymatic functionality into novel MEMS devices.

In this study, we report the development of a microenvironment probe station capable of detecting the effect of small changes to the local environment around a carbon nanotube conduction channel. The microenvironment probe station is highly versatile and is used to characterize alterations in carbon nanotube field effect transistor electrical behavior in response to changes in temperature, gas species, infrared and ultraviolet light. All devices were electrically characterized in atmospheric, ultrahigh vacuum and oxygen-rich environments. The results suggest that devices could be changed from n-type at 1 x 10(-8) torr through an intermediate ambipolar state at 1 x 10(-4) torr to p-type at atmosphere solely by increasing the oxygen concentration. The average resistance of these carbon nanotube field effect transistors after annealing was observed to decrease by approximately 54% from their initial value under ultrahigh vacuum to their final value in the presence of pure oxygen while corresponding threshold voltages shifts were also observed. Illumination with infrared light resulted in a approximately 10% increase in drain current with an estimated response time

We demonstrate room temperature detection of isolated single 19 nm super-paramagnetic nanoparticles (SPNs) with a wide-field optical microscope platform suitable for biological integration. The particles are made of magnetite (Fe3O4) and are thus non-toxic and biocompatible. Detection is accomplished via optically detected magnetic resonance imaging using nitrogen-vacancy defect centers in diamond, resulting in a DC magnetic field detection limit of 2.4 μT. This marks a large step forward in the detection of SPNs, and we expect that it will allow for the development of magnetic-field-based biosensors capable of detecting a single molecular binding event.

We present coupled GaP resonator-waveguide structures on diamond fabricated from single-crystalline, epitaxially grown material. This progress is critical for the integration of nitrogen-vacancy centers in diamond into optical networks with active, linear electro-optic devices.