Use Of Aluminum Nitride Research Articles

High-efficiency fiber-to-chip interface for aluminum nitride quantum photonics

Integrated nonlinear photonic circuits received rapid development in recent years, providing all-optical functionalities enabled by cavity-enhanced photon-photon interaction for classical and quantum applications. A high-efficiency fiber-to-chip interface is key to these integrated photonic circuits for quantum information tasks, as photon-loss is a major source that weakens quantum protocols. Here, overcoming material and fabrication limitation of thin-film aluminum nitride by adopting a stepwise waveguiding scheme, we demonstrate low-loss adiabatic fiber-optic couplers in aluminum nitride films with a substantial thickness (∼600 nm) for optimized nonlinear photon interaction. For telecom (1550 nm) and near-visible (780 nm) transverse magnetic-polarized light, the measured insertion loss of the fiber-optic coupler is -0.97 dB and -2.6 dB, respectively. Our results will facilitate the use of aluminum nitride integrated photonic circuits as efficient quantum resources for generation of entangled photons and squeezed light on microchips.

Comparison of AlN vs. SIO2/LiNbO3 Membranes as Sensitive Elements for the SAW-Based Acceleration Measurement: Overcoming the Anisotropy Effects.

We propose the use of aluminum nitride (AlN) membranes acting as sensitive elements for the surface acoustic wave (SAW)-based acceleration measurement. The proposed solution is compared against existing prototypes based on the use of quartz (SiO2)/lithium niobate (LiNbO3) membranes that are characterized by extensive anisotropic properties. Using COMSOL Multiphysics 5.4 computer simulations we show explicitly that sensitive elements based on less anisotropic AlN membranes overcome both the low sensitivity limitations of SiO2 and low temperature stability of LiNbO3. Moreover, AlN membranes exhibit nearly double the robustness against irreversible mechanical deformations when compared against SiO2, which in turn allows for further 1.5-fold sensitivity enhancement over LiNbO3 based sensors. Taking into account their acceptable frequency characteristics, we thus believe that the AlN membranes are a good candidate forsensitive elements especially for high acceleration measurements.

Facile synthesis of powder-based processing of porous aluminum nitride

The use of aluminum nitride (AlN) has recently begun to be explored for advanced functional applications. For some particular applications, it is more advantageous to use porous-structured AlN, simply because it can provide a greater surface area and higher permeability. However, porous or bulk AlN is very difficult to achieve due mainly to its high melting point (2200°C). This study proposes a new novel processing method to synthesize porous AlN through a complete transformation from porous aluminum (Al) using a remarkably low nitriding/sintering temperature (620°C) as opposed to only the surface nitride AlN-Al core composite systems reportedly at or above 1000°C in the literature. A uniform microporous bead structure of porous AlN with a mean pore size of 74.0±27.7μm was obtained that also contained nanoparticles ranging from 80 to 230nm that covered the surface.

Thick Film Materials for High Power Hybrid Circuits on Aluminum Nitride

Abstract For over 40 years, the substrate of choice for designing and fabricating traditional hybrid circuits has been alumina. It has provided the required mechanical strength, electrical resistivity, and thermal performance needed for proper circuit operation. Over the past several years however, we have experienced a shift in hybrid technology towards electronic devices with highly complex, dense circuit configurations that produce more power and consequently, more heat than previous designs. This requires the use of a substrate with a higher thermal conductivity to properly manage the heat transfer and dissipation in order to maintain optimum performance and functionality of the end device. The thermal properties displayed by aluminum nitride provide design engineers with a reliable alternative to traditional alumina. While creating new and exciting possibilities, the use of aluminum nitride also creates a different set of challenges for thick film suppliers and circuit fabricators. Due to the thermal expansion mismatch, as well as the chemical changes that occur to the substrate which affect adhesion during the firing process, thick film pastes previously suitable for alumina are typically not compatible with aluminum nitride. To overcome this challenge and the performance demands of high power, high reliability circuit applications, a new line of RoHS and REACH compliant thick film pastes has been developed. The following conductors are available: silver, silver/palladium, silver/platinum, copper, and gold. In addition, we have developed two resistor pastes and a compatible overglaze. This paper will discuss the aforementioned thick films and their critical performance properties before and after reliability testing. This includes adhesion for the conductors, resistance and TCR for the resistors.

Enhanced actuation of nanocrystalline diamond microelectromechanical disk resonators with AlN layers

A great potential of the use of aluminum nitride (AlN) to enhance the actuation of nanocrystalline diamond (NCD) microelectromechanical system disk resonators is revealed. A disk resonator with a unimorph (AlN/NCD) structure is fabricated by depositing a c-axis oriented AlN on a capacitive NCD disk resonator. The unimorph resonator is piezoelectrically actuated with flexural whispering gallery modes with a relatively large electrode gap spacing, i.e., the spacing which is greater than 1 μm, although this is not possible for the capacitive NCD disk resonator. This result is explained by a finite element method simulation where the piezoelectric actuation turns out to be more effective than the capacitive actuation when the electrode gap spacing is >0.8 μm. The simulation also shows that the electrode gap spacing required for the capacitive actuation to be more effective than the piezoelectric actuation exponentially decreases when the resonator dimension is scaled down for higher frequency operations. Our study indicates that the use of AlN is promising to decrease impedance levels of NCD disk resonators especially for their higher frequency operations.

The use of aluminum nitride to improve Aluminum-26 Accelerator Mass Spectrometry measurements and production of Radioactive Ion Beams

We present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of 26Al isotopes. The measurement of 26Al in geological samples by AMS is typically conducted on Al2O3 targets. However, Al2O3 is not an ideal source material because it does not form a prolific beam of Al− required for measuring low-levels of 26Al. Multiple samples of aluminum oxide (Al2O3), aluminum nitride (AlN), mixed Al2O3–AlN as well as aluminum fluoride (AlF3) were tested and compared using the ion source test facility and the stable ion beam (SIB) injector platform at the 25-MV tandem electrostatic accelerator at Oak Ridge National Laboratory. Negative ion currents of atomic and molecular aluminum were examined for each source material. It was found that pure AlN targets produced substantially higher beam currents than the other materials and that there was some dependence on the exposure of AlN to air. The applicability of using AlN as a source material for geological samples was explored by preparing quartz samples as Al2O3 and converting them to AlN using a carbothermal reduction technique, which involved reducing the Al2O3 with graphite powder at 1600°C within a nitrogen atmosphere. The quartz material was successfully converted to AlN. Thus far, AlN proves to be a promising source material and could lead towards increasing the sensitivity of low-level 26Al AMS measurements. The potential of using AlN as a source material for nuclear physics is also very promising by placing 26AlN directly into a source to produce more intense radioactive beams of 26Al.

Ken Lakin [In Memoriam

Recounts the life and professional achievements of Ken Lakin. Kenneth Lakin was born on 14 January 1941 in Grand Rapids, Michigan, USA. He graduated from the University of Michigan with B.S. and M.S. degrees in physics, mathematics, and electrical engineering and received his Ph.D. in applied physics from Stanford University in 1969. Dr. Lakin made pioneering contributions to microwave acoustic materials, devices, and applications, where he introduced consistently new and innovative ideas. He worked in the microwave acoustic field for more than 40 years, and his work significantly advanced the state of the art. He is probably best known for his following achievements: He played a key role in the successful demonstration of the use of aluminum nitride as a material for microwave acoustic applications; He demonstrated the first FBAR device in the early eighties, the socalled solidly mounted resonator (SMR). Dr. Lakin passed away on 24 November 2012.

Combustion synthesis of AlN with melamine as an additive

Melamine (C3H6N6) was used as an additive for synthesizing aluminum nitride by combustion synthesis. It was found that at least 0.1 M of melamine addition to 1 M of aluminum and 0.8 MPa of nitrogen pressure were necessary to initiate a stable reaction. In addition to melamine, however, use of aluminum nitride as a diluent and application of forced nitrogen flow yielded better results. Analyzing the reaction temperatures, reaction rates, nitrogen contents, x-ray diffraction patterns, and scanning electron microscopy photographs, the optimum conditions for synthesizing AlN were established: (i) reactants were 90 wt% (1 M Al + 0.1 M melamine) + 10 wt% AlN diluent, (ii) chamber pressure was 0.9 MPa, and (iii) nitrogen flow rate was 15 l/min. Under these conditions, aluminum nitride with the stoichiometric nitrogen content of 34 wt% could be obtained.

Estudo do nitreto de alumínio para aplicações termo-mecânicas

O nitreto de alumínio é muito utilizado como material semicondutor em dispositivos óptico-eletrônicos na qual sua alta condutividade térmica permite uma boa dissipação de calor. Por outro lado, devido à alta resistência mecânica e boa estabilidade estrutural à alta temperatura, tem sido crescente o seu estudo para aplicações termo-mecânica levando em considerações os avanços tecnológicos no processamento e caracterização destes materiais. Neste trabalho serão apresentados os resultados dos estudos de prensagem a quente do nitreto de alumínio aditivado com 5%, 10% e 20% de uma mistura contendo Al2O3 + Y2O3. A massa específica foi determinada de acordo com a norma ASTM C20-87, as fases presentes por difração de raios X e as análises microestruturais por microscopia eletrônica de varredura. A microdureza e tenacidade à fratura foram avaliadas pelo método de indentação Vickers. Os resultados promissores alcançados de densificação, próximos à densidade teórica, e propriedades mecânicas, mostraram a viabilidade da utilização do AlN em aplicações estruturais.

Indirect-Bonded Metallization of Aluminum Nitride

AbstractThe use of aluminum nitride (AIN) as a substrate and packaging material for microcircuit applications is of present interest due to its many advantageous physical properties. A limitation to the widespread use of AIN is the lack of an adequate metallization system. The most common method of achieving high-integrity metallized ceramics is through the use of indirect-bonded metallizations. A wide range of intermediate bonding materials are used, for example glasses, oxide mixtures, and active metals. In this paper, the indirect-bonded metallization of AIN will be reviewed and discussed. Requirements which must be considered in producing successful metallizations include; wetting of the substrate and the metal by the intermediate phase and the reactivity between the intermediate phase and the substrate. The reactions which occur in many of the systems considered can be predicted by examination of thermodynamic data.

The influence of contact angle, wettability, and reactivity on the development of indirect-bonded metallizations for aluminum nitride

The use of aluminum nitride (AIN) as a substrate and packaging material for microcircuit applications is of present interest due to its many advantageous physical properties. A limitation to the widespread use of AIN is the lack of an adequate metallization system. In this paper, the indirect-bonded metallization of AIN will be reviewed-in particular, thick-film metallization, where the intermediate material is often a glass, and brazing, where the intermediate material is an active metal. Requirements which must be considered in producing successful metallizations include wetting of the substrate and the metal by the intermediate phase, and the reactivity between the intermediate phase and the substrate. In the case of thick-film metallization, these reactions can often be deleterious to the properties of the metal layer. In brazing, reaction between the active metal and the substrate is essential for achieving wetting of the ceramic surface by the molten braze and, thus, for producing high-strength joints. The reactions which occur in many of the systems considered can be predicted by examination of thermodynamic data.