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Growth of Si-doped AlN on sapphire (0001) via pulsed sputtering
摘要： The Si-doped AlN films were grown on sapphire (0001) by pulsed sputtering deposition (PSD), and their structural and electrical properties were investigated. A combination of PSD and high-temperature annealing process enabled the growth of high-quality AlN (0001) epitaxial films on sapphire (0001) substrates with atomically flat stepped and terraced surfaces. The transmission electron microscopy observations revealed that the majority of the threading dislocations in AlN belonged to the mixed- or edge-type, with densities of 2.8 × 108 and 4.4 × 109 cm?2, respectively. The Si-doping of AlN by PSD yielded a clear n-type conductivity with a maximum electron mobility of 44 cm2 V?1 s?1, which was the highest value reported for AlN that was grown on sapphire. These results clearly demonstrated the strong potential of the PSD technique for growing high-quality conductive n-type AlN on sapphire.
关键词： n-type conductivity,Si-doped AlN,pulsed sputtering deposition,electron mobility,sapphire
更新于2025-09-10 09:29:36
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Thermally stimulated luminescence properties of Eu-doped AlN ceramic
摘要： We synthesized non- and Eu-doped AlN ceramics by the spark plasma sintering (SPS) method and characterized their photoluminsecence (PL) and thermally stimutrated luminescence (TSL) properties. In the PL properties, the non-doped AlN samples showed a broad emission peaking around 400 nm. In contract, the Eu-doped AlN samples showed two broad emission bands around 400 and 520 nm, and two sharp emission peaks at 610 and 700 nm. The origins of the emission peaks at 400, 520, 610 and 700 nm were due to complexes composed of Al vacancy and O impurity, 5d-4f transitons of Eu2+, 5D0→7F2 and 5D0→7F4 transitions of Eu3+, respectively. Regarding the TSL properties, the TSL intensities of the 0.01 and 0.1% Eu-doped AlN samples were higher than that of the non-doped AlN sample. It was confirmed that the 0.1% Eu-doped AlN showed a good linearity from 0.01 to 1000 mGy.
关键词： dosimeter,TSL,Eu ion,X-rays,AlN
更新于2025-09-10 09:29:36
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Fabrication and characterization of AlN based Piezoelectric Micromachined Ultrasonic Transducer for contact sensing
摘要： In this paper, we present an aluminum nitride (AlN) Piezoelectric Micro-machined Ultrasonic Transducer (PMUT) for contact sensing, which is a suspended stacked layers Si/Mo electrode /AlN/Al electrode in Silicon substrate. In order to obtain a Si elastic layer with a small thickness, DRIE Si process is utilized to make a deep cavity on the backside of Si substrate to suspend the stacked layers of PMUT device. AlN based PMUT sample is fabricated, having a suspended stacked layers of Si/Mo/AlN/Al measured about 5?m/0.1?m /0.8?m/1?m respectively in the thickness, 100?m in the radius of Si film. The AlN film has a measured surface roughness of 5nm by AFM and has (001) orientation peak by XRD analysis.
关键词： characterization,PMUT,AlN
更新于2025-09-10 09:29:36
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Characterization of Er-doped AlN films prepared by RF magnetron sputtering
摘要： Er-doped AlN thin film were deposited on sapphire substrates (0001) by RF magnetron sputtering at different sputtering times. The crystalline structure, surface morphology and electrical properties of the thin films have been investigated. The XRD patterns and the SEM sectional diagram indicate that Er-doped AlN thin films presents the preferred orientation of C axis. The crystalline quality of the films rises first and then decreases with the increase of sputtering time and reaches best at 90 minutes. Piezoelectric coefficient d33 indicates maximum value of 9.53pm/V. Correspondingly, the best surface morphology of thin film was obtained at 90 minutes and the surface roughness reached a minimum of 2.012 nm. In addition, the change of resistance is same with change of the crystalline quality and the resistivity reached a maximum of 4.36*1012Ω?cm at 90minutes.
关键词： piezoelectric properties,Er-doped AlN,crystal structure,resistivity,sputtering time,magnetron sputtering
更新于2025-09-10 09:29:36
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Temperature dependent electrical properties of AlN/Si heterojunction
摘要： AlN is an integral part of many Si based electronic, optoelectronic, and electromechanical devices. The transport of charge carriers and their recombination at the AlN (0002)/Si (111) interface become crucial for the performance and reliability of such devices. In this work, we have studied the temperature dependent current-voltage (I-V-T) characteristics of AlN/Si heterojunctions to gain a deeper understanding. The analysis of the I-V-T characteristics interestingly suggested a temperature dependent turn-on voltage in the forward bias of the Schottky barrier. Also, the Schottky barrier itself was found to be temperature dependent as expected. We have qualitatively explained the temperature dependence of the turn-on voltage in terms of trap states at the AlN/Si heterojunction.
关键词： electrical properties,temperature dependent,AlN/Si heterojunction,Schottky barrier,trap states
更新于2025-09-10 09:29:36
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Direct van der Waals Epitaxy of Crack-Free AlN Thin Film on Epitaxial WS2
摘要： Van der Waals epitaxy (vdWE) has drawn continuous attention, as it is unlimited by lattice-mismatch between epitaxial layers and substrates. Previous reports on the vdWE of III-nitride thin film were mainly based on two-dimensional (2D) materials by plasma pretreatment or pre-doping of other hexagonal materials. However, it is still a huge challenge for single-crystalline thin film on 2D materials without any other extra treatment or interlayer. Here, we grew high-quality single-crystalline AlN thin film on sapphire substrate with an intrinsic WS2 overlayer (WS2/sapphire) by metal-organic chemical vapor deposition, which had surface roughness and defect density similar to that grown on conventional sapphire substrates. Moreover, an AlGaN-based deep ultraviolet light emitting diode structure on WS2/sapphire was demonstrated. The electroluminescence (EL) performance exhibited strong emissions with a single peak at 283 nm. The wavelength of the single peak only showed a faint peak-position shift with increasing current to 80 mA, which further indicated the high quality and low stress of the AlN thin film. This work provides a promising solution for further deep-ultraviolet (DUV) light emitting electrodes (LEDs) development on 2D materials, as well as other unconventional substrates.
关键词： van der Waals epitaxy,AlN thin film,MOCVD,WS2
更新于2025-09-09 09:28:46
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Tuneable Q-Factor of MEMS Cantilevers with Integrated Piezoelectric Thin Films
摘要： In atomic force microscopes (AFM) a resonantly excited, micro-machined cantilever with a tip is used for sensing surface-related properties. When targeting the integration of AFMs into vacuum environments (e.g., for enhancing the performance of scanning electron microscopes), a tuneable Q-factor of the resonating AFM cantilever is a key feature to enable high speed measurements with high local resolution. To achieve this goal, in this study an additional mechanical stimulus is applied to the cantilever with respect to the stimulus provided by the macroscopic piezoelectric actuator. This additional stimulus is generated by an aluminum nitride piezoelectric thin film actuator integrated on the cantilever, which is driven by a phase shifted excitation. The Q-factor is determined electrically by the piezoelectric layer in a Wheatstone bridge configuration and optically verified in parallel with a laser Doppler vibrometer. Depending on the measurement technique, the Q-factor is reduced by a factor of about 1.9 (electrically) and 1.6 (optically), thus enabling the damping of MEMS structures with a straight-forward and cheap electronic approach.
关键词： phase shifted excitation,vacuum,electronically tuneable Q-factor,AFM,MEMS cantilever,AlN,piezoelectric,peak shaping
更新于2025-09-09 09:28:46
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High-efficiency electron-beam-pumped sub-240-nm ultraviolet emitters based on ultra-thin GaN/AlN multiple quantum wells grown by plasma-assisted molecular-beam epitaxy on <i>c</i> -Al <sub/>2</sub> O <sub/>3</sub>
摘要： We report the internal structures and emission properties of GaN/AlN single- and multiple-quantum-well (QW) heterostructures with well widths of dw = 1–4 monolayers (MLs), grown by plasma-assisted molecular-beam epitaxy on c-sapphire at metal-rich conditions and low temperatures (>700 °C). The formation of plane QWs with abrupt symmetrical interfaces is con?rmed by both scanning transmission electron microscopy and X-ray di?raction analysis. Pulse-scanning and continuous-wave output powers of 150 and 28 mW, respectively, at a peak emission wavelength of 235 nm were achieved at 300 K in an electron-beam-pumped deep-ultraviolet (1.5 ML-GaN/5.5 nm-AlN)360 multiple-QW emitter with a maximum e?ciency of 0.75%.
关键词： plasma-assisted molecular-beam epitaxy,electron-beam-pumped,deep-ultraviolet emitters,GaN/AlN,quantum wells
更新于2025-09-04 15:30:14
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190 GHz high power input frequency doubler based on Schottky diodes and AlN substrate
摘要： This paper presents the design and development of a 190 GHz Schottky-diode frequency doubler (×2 multiplier) which can handle up to 260 mW input power. In order to increase the power handling capability, a modeling approach incorporating computer-aided design (CAD) load-pull techniques to characterize the diode performance is proposed. By the use of this approach, e?ects of several critical diode parameters on the power handling issue are quantitatively investigated and based on the analysis, a discrete diode chip is designed for the doubler. To ensure rapid heat sink in the doubler circuitry, low cost aluminum nitride ceramic (AlN) is selected as the dielectric material of the circuit substrate, which has signi?cantly better thermal conductivity compared with currently widely-used fused quartz. The doubler circuitry is based on a balanced con?guration, which brings a merit of avoiding the use of a ?lter for the input and output signal isolation. The doubler circuit is optimized by co-simulation using ANSYS’s HFSS and Keysight’s ADS. The measurements show that the doubler can handle up to 260 mW input power with a power conversion e?ciency of nearly 8%, resulting in 20 mW output power at 193 GHz.
关键词： high power,AlN substrate,Schottky diodes,CAD load-pull,terahertz multiplier
更新于2025-09-04 15:30:14
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High magnetoelectric coupling in Si-integrated AlN/NiMnIn thin film double layers at room temperature
摘要： The current study explores the presence of strong magnetoelectric (ME) coupling in a sputtered deposited NiMnIn/aluminum nitride (AlN) heterostructure on an Si substrate. The X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy results confirm the formation of a pure AlN wurtzite phase in the ME heterostructure. The magnetization vs temperature measurement shows the presence of the martensite transformation region of the NiMnIn/AlN heterostructure. The magnetic measurements exhibit the room temperature ferromagnetic nature of the NiMnIn/AlN heterostructure. The NiMnIn/AlN ME heterostructure was found to have a high ME coupling coefficient of (cid:2)99.2 V/cm Oe at Hdc ? 300 Oe. The induced ME coupling coefficient shows a linear dependency on Hac up to 8 Oe.
关键词： room temperature,Si-integrated,thin film,magnetoelectric coupling,AlN/NiMnIn
更新于2025-09-04 15:30:14