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Zenita Aisah Rahmayanti,1 Dudi Aripin,1 Anna Muryani,1 Yolanda Yolanda,1 Hendra Dian Adhita Dharsono,1 Sandro Mihradi,2 Satrio Wicaksono2 1Department of Conservative Dentistry, Faculty of Dentistry, Universitas Padjadjaran, Bandung, Indonesia; 2Faculty of Mechanical and Aerospace Engineering, Bandung Institute of Technology, Bandung, IndonesiaCorrespondence: Anna Muryani, Department of Conservative Dentistry, Faculty of Dentistry, Universitas Padjadjaran, Jl. Sekeloa Selatan no. 1, Bandung, 40123, Indonesia, Tel +62 896 19972132, Email anna.muryani@unpad.ac.idPurpose: This research aimed to describe the stress distribution of an endodontically treated tooth with a mesio-occluso-distal (MOD) cavity restored with direct composite reinforced with polyethylene and e-glass ribbon fiber.Methods: This research was a descriptive study using the finite element method. A 3D model of the mandibular first molar solid after endodontic treatment with class II MOD preparation was prepared using Solidworks software. Finite element simulation was carried out using Abaqus software. In the first simulation, 180 N force was applied (vertically 90° perpendicular to the occlusal surface) at four points of loading: the tip of the mesiobuccal and distobuccal cusp, central fossa, and distal marginal ridge. For the second simulation, a 100 N force was applied at a 45° lateral angle to the occlusal surface at two loading points: the lingual slope of the mesiobuccal and distobuccal cusp.Results: This study showed that the stress concentration was located in the occlusal pit and fissure, CEJ distal area, bifurcation in dentin, and the 1/3 cervical area of root dentin. The stress value generated after vertical and lateral force did not exceed the tooth and restoration’s compressive and tensile strength value. The failure occurred at the interface of enamel and composite near the loading point area due to vertical load, both on polyethylene and e-glass fiber ribbon-reinforced composite restoration. Stress distribution of an endodontically treated tooth with a MOD cavity restored with ribbon fiber-reinforced composite using the finite element method showed that the highest stress concentration occurred on the surface close to the loading point, in narrow, concave, and sharp areas, and more apically for endodontically treated teeth.Conclusion: Neither the tooth nor restoration failed after vertical and horizontal loads. The interface between enamel and composite on the occlusal surface failed.Keywords: direct composite restoration, fiber-reinforced composite, wallpapering technique, finite element

The improvement of GaInNAs/GaAs p-i-n photodetector responsivity following the incorporation of antimony into the quaternary material and the measurements from deep level transient spectroscopy (DLTS) to support the effects leading to such improvement is reported. The results have shown that the incorporation of Sb into GaInNAs has effectively improved the performance of the p-i-n photodetector device.

The effect of the growth temperature of GaAsSbN is studied by using a combination of low temperature photoluminescence (PL), x-ray diffraction (XRD) reciprocal space maps (RSMs) and photocurrent response measurements for the application as the intrinsic layer in GaAs-based 1.3 micro m p-i-n photodetector. The RSMs have revealed traces of point defects and segregation of N and Sb, which might have a detrimental effect on the photocurrent responsivity.

The effect of annealing on the photoluminescence (PL) in GaAsSbN/GaAs quantum wells (QWs) grown by solid-source molecular-beam epitaxy is investigated by low-temperature PL measurements. The results show that the optical quality of QW can be improved in terms of PL intensity and full width at half maximum (FWHM) under the optimum condition.

Insomnia is a disorder to start, maintain, and wake up from sleep, has many sufferers in the world. For patients in remote locations who suffer from insomnia, which requires testing, the gold standard performed requires patients to take the time and travel to the health care center. By making alternatives to remote sleep insomnia testing using electrocardiography and electromyography connected to the internet of things can solve the problem of patients' access to treatment. Delivery of patient data to the server is done to make observations from the visualization of patient data in real-time. Furthermore, using artificial neural networks was used to classify EMG, ECG, and combine patient data to determine patients who have Insomnia get resulted in patient classification errors around 0.2% to 2.7%. [ABSTRACT FROM AUTHOR]

We present the reverse-bias current-voltage and deep-level transient spectroscopy (DLTS) characteristics of a Ga0.90In0.10N0.033As0.967/GaAs positive-intrinsic-negative photodiode (Eg=0.92 eV) and a trap-assisted tunneling model which considers generation-recombination and tunneling mechanisms. Using trap parameters obtained from the DLTS measurement, the model generates current-voltage characteristics of the photodiode, which were found to be in good agreement with experimental current-voltage curves at different temperature. The model also suggests that high dark current at low reverse-bias voltage is caused by the presence of traps which have low activation energy. Furthermore, it is predicted that approximately ten times reduction in the dark current can be achieved when the trap concentration of type H-1 (Ea=0.15 eV) is reduced by one order. On the other hand, a similar reduction in defect concentration of type H-2 (Ea=0.40 eV), which is nearer to midgap does not produce the same effect. [ABSTRACT FROM AUTHOR]

A GaAsSbN layer closely lattice matched to GaAs was used as an intrinsic layer (i layer) in a GaAs/GaAsSbN/GaAs p-i-n photodiode with response up to 1.3 μm. Deep level transient spectroscopy measurement on the GaAs/GaAsSbN/GaAs reveals two types of hole traps (HTs) in the GaAsSbN i layer; (i) HT1: a shallow N-related defect state (Ea∼0.10–0.12 eV) and (ii) HT2: an AsGa point defect-related midgap defect state with Ea∼0.42–0.43 eV. Reduction in growth temperature from 480 to 420 °C reduces the HT2 trap concentration from 4×1015 to 1×1015 cm-3, while increases the HT1 trap concentration from 1×1014 to 7×1014 cm-3. Reduction in the HT2 trap concentration following growth temperature reduction was attributed to the suppression of AsGa point defect formation. Evidence of possible change of the AsGa midgap state to a shallow level defect due to the formation of (AsGa–NAs) pairs was also suggested to have increased the HT1 trap concentration and reduced the HT2 trap concentration. An ∼4 dBm improvement in photoresponse under 1.3 μm laser excitation and approximately eight times reduction in dark current at -8 V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the AsGa-related midgap trap concentration in the sample grown at 420 °C. [ABSTRACT FROM AUTHOR]

GaAsSbN layers closely lattice-matched to GaAs were studied for application as the intrinsic layer in GaAs-based 1.3 μm p-i-n photodetector. The GaAsSbN was grown as the intrinsic layer for the GaAs/GaAsSbN/GaAs photodetector structure using solid-source molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and valved antimony cracker source. The lattice mismatch of the GaAsSbN layer to GaAs was kept below 4000 ppm, which is sufficient to maintain coherent growth of ∼0.45 μm thick GaAsSbN on the GaAs substrate. The growth temperature of the GaAsSbN layer was varied from 420–480 °C. All samples exhibit room temperature photocurrent response in the 1.3 μm wavelength region, with dark current density of ∼0.3–0.5 mA/cm2 and responsivity of up to 33 mA/W at 2 V reverse bias. Reciprocal space maps reveal traces of point defects and segregation (clustering) of N and Sb, which may have a detrimental effect on the photocurrent responsivity. [ABSTRACT FROM AUTHOR]

Deep level transient spectroscopy measurement on the GaAs/GaAsSbN/GaAs has shown two types of hole traps (HTs) in the GaAsSbN intrinsic layer (i layer). The improvement in photoresponse under 1.3 [mu]m laser excitation and approximately eight times reduction in dark current at -8 V reverse bias are attributed to the reduction in the overall trap concentration.

The effect of annealing on the photoluminescence (PL) in GaAsSbN/GaAs quantum wells (QWs) grown by solid-source molecular-beam epitaxy has been investigated. The annealing time and temperature are 5 min and 650–750 °C, respectively. Low-temperature (4 K) PL peaks shift to higher energies with the annealing temperatures. An As–Sb atomic interdiffusion at the heterointerface is proposed to model this effect. The compositional profile of the QW after interdiffusion is described by an error function distribution and calculated by a ten-band k·p method. The estimated interdiffusion constants D are ∼10-17–10-16 cm2/s in the above temperature range and an activation energy of 1±0.4 eV is obtained. [ABSTRACT FROM AUTHOR]

We report the performance of a 1 eV GaNAsSb photovoltaic cell grown on a Si substrate with a SiGe graded buffer grown using molecular beam epitaxy. For comparison, the performance of a similar 1 eV GaN0.018As0.897Sb0.085 photovoltaic cell grown on a GaAs substrate was also reported. Both devices were in situ annealed at 700 ℃ for 5min, and a significant performance improvement over our previous result was observed. The device on the GaAs substrate showed a low open circuit voltage (VOC) of 0.42V and a short circuit current density (JSC) of 23.4mA/cm² while the device on the Si substrate showed a VOC of 0.39V and a JSC of 21.3mA/cm². Both devices delivered a quantum efficiency of 50%-55% without any anti-reflection coating. [ABSTRACT FROM AUTHOR]

We report a photoconductive switch using low temperature grown GaNAsSb as the active material. The GaNAsSb layer was grown at 200 °C by molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and a valved antimony cracker source. The low temperature growth of the GaNAsSb layer increased the dark resistivity of the switch and shortened the carrier lifetime. The switch exhibited a dark resistivity of 107 Ω cm, a photo-absorption of up to 2.1 μm, and a carrier lifetime of ∼1.3 ps. These results strongly support the suitability of low temperature grown GaNAsSb in the photoconductive switch application. [ABSTRACT FROM AUTHOR]

We report on the small-signal high-frequency response of a GaNAsSb/GaAs pin waveguide photodetector at 1.55-\mu\m wavelength. The GaNAsSb absorbing layer with 3.5% N and 18% Sb is sandwiched by GaAs-cladding layers. The device of an 8-\mu\m ridge width and 15- \mu\m ridge length has a dc responsivity of 0.44 A/W and an 11-GHz cutoff frequency at 5-mW optical illumination at a bias condition of -5 V. A higher cutoff frequency of 14.3-GHz is achieved on the smallest device of 4- \mu\m ridge width and 17-\mu\m ridge length with a responsivity of 0.2 A/W at a reverse bias condition of -1 V. [ABSTRACT FROM PUBLISHER]

Indium antimonide (InSb) is a promising material for mid- and long-wavelength infrared device applications. However, because of material’s small band gap and low melting point, reproducibility of high quality epitaxial InSb is difficult to obtain. This article reports growth experimentations for determining suitable conditions for growing InSb on InSb(100) substrate using solid source molecular beam epitaxy. The effects of growth temperature and antimony/indium (Sb/In) flux ratio on epilayer structure, surface roughness, and electronic properties were investigated. The process of oxide desorption observed from reflection high energy electron diffraction pattern is reported. A three-layer model was used to extract the electronic properties of the epilayer, taking into account the effect of parallel conduction. Process conditions for good structural and electronic properties of the InSb epilayer, which includes substrate temperature and flux ratio, have been established in this study and reported herein. [ABSTRACT FROM AUTHOR]

Abstract: GaAsSbN is a potential material for GaAs-based long wavelength optoelectronic devices. In this work, using solid source molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and a antimony cracker source, we will demonstrate closely lattice-matched condition of GaAsSbN/GaAs with lattice mismatch <1000ppm. Closely lattice-matched GaAsSbN/GaAs samples were obtained which showed room temperature and 4K photoluminescence emission at ∼1300nm, with N and Sb concentration of ∼2.3% and ∼7%, respectively. Competitive incorporation of Sb and N was observed, as the presence of Sb promotes N incorporation. This competition enhances Sb-surfactant effect observed in GaAsSbN layer grown with a slight compressive strain. [Copyright &y& Elsevier]

The authors report the demonstration of high-speed GaNAsSb/GaAs p-i-n waveguide photodetector grown by molecular beam epitaxy technique. A 0.4-µm-thick GaNAsSb core layer with 3.3% of N and 8% of Sb for detection wavelength over 1.3 µm is sandwiched by GaAs and AlGaAs cladding layers. The device exhibits a record value of cutoff frequency of 16.5 GHz. [ABSTRACT FROM AUTHOR]

We present the dc performance of a high-quantum-efficiency GaNAsSb/GaAs p-i-n waveguide photodetector. GaNAsSb with N and Sb contents of 3.3% and 8%, respectively, is sandwiched by AlGaAs/GaAs cladding layers. Two types of device epilayer structures, i.e., with and without AlGaAs cladding layer, show high responsivity values of 0.72 and 0.55 A/W, respectively, at a reverse bias voltage of 10 V and a wavelength of 1.3 µm. These correspond to internal quantum efficiencies of 96.7% and 73.9%, respectively. A linear increase in photocurrent with an increase in optical power up to 8 mW and also a high reverse breakdown voltage of -16.6 V were obtained. [ABSTRACT FROM AUTHOR]

Room-temperature full GaAs-based near-infrared (NIR) upconversion has been demonstrated by connecting lattice-matched GaNAsSb/GaAs p-i-n photodetectors in series with commercial GaAs/AlGaAs light-emitting diodes (LEDs). Due to the avalanche gain in GaNAsSb/GaAs photodetectors and high internal efficiency in GaAs/AlGaAs LEDs, the upconversion efficiency of the integrated system reaches 0.048 W/W under -7 V bias, much higher than any existing NIR upconverters without amplifying structures. We have further investigated the dependence of the upconversion efficiency on applied bias and incident light intensity. The present work establishes an experimental base for direct epitaxial growth of full GaAs-based NIR upconverters with high upconversion efficiencies. [ABSTRACT FROM AUTHOR]

We present a GaNAsSb/GaAs p-i-n waveguide photodetector operating in the 1.0–1.6 μm wavelength range with enhanced photoresponsivity compared to a top-illuminated photodetector fabricated using the same material system. The device consists of a strained GaNAsSb layer, with N and Sb contents of 3.5% and 18%, respectively, sandwiched between GaAs:Si (n-type) and GaAs:C (p-type) layers. X-ray reciprocal space map of the GaNAsSb layer before device fabrication showed that the film relaxation is ∼1%. At 1.55 μm, photoresponsivities of 0.25 and 0.29 A/W for devices with 6.5 and 10 μm ridge width, respectively, was demonstrated. [ABSTRACT FROM AUTHOR]

We report on the fabrication of high-speed GaNAsSb photodetector for multigigabit operation at 1.3 μm wavelength. The 2 μm thick bulk GaNAsSb photoabsorption layer contains 3.3% of N and 8% of Sb, resulting in optical band gap of ∼0.9 eV suitable for near infrared operation up to wavelengths of about 1380 nm. By using the bulk photoabsorption layer, we have fabricated GaNAsSb photodetector with high dc responsivity of 0.12 A/W at 1.3 μm wavelength. The photodetector exhibits 3 dB cutoff frequency at 1.3 μm wavelength of 4.5 GHz. Furthermore, 5 Gb/s fiber-optic transmission at 1.3 μm wavelength is demonstrated using the GaNAsSb photodetector. [ABSTRACT FROM AUTHOR]

We demonstrate a 1.55 μm GaAs/GaNAsSb/GaAs optical waveguide grown by molecular beam epitaxy as an alternative to the AlGaAs/GaAs system. The 0.4-μm-thick GaNAsSb guiding layer contains ∼3.5% of N and 9% of Sb, resulting in optical band gap of 0.88 eV. The refractive index of the GaNAsSb layer was measured from 800 to 1700 nm. The GaNAsSb layer has a refractive index value of 3.42 at 1.55 μm wavelength. The propagation loss measured using the Fabry–Pérot resonance method was found to be affected by nitrogen-related defect absorption. [ABSTRACT FROM AUTHOR]

AlGaAs/GaAsNSb heterojunction bipolar transistors (HBTs) with low turn-on voltage have been fabricated. The turn-on voltage of the device fabricated from an as-grown sample is ~180 mV lower than that of a conventional AlGaAs/GaAs HBT. The effect of rapid thermal annealing on device performance is an increase in the gain from ~8.5 to ~20. However, the knee voltage of the annealed sample (~3 V), as well as the turn-on voltage, is also higher compared with that of the as-grown sample (~1.5 V). [ABSTRACT FROM AUTHOR]

The authors report on picosecond pulse response GaNAsSb/GaAs p-i-n photodetectors grown by molecular beam epitaxy in conjunction with a rf plasma-assisted nitrogen source. The 2 μm thick GaNAsSb photoabsorption layer contains 3.3% of N and 8% of Sb resulting in a dc photoresponse up to 1380 nm wavelength. Dark current densities at 0 and -5 V are 1.6×10-5 and 13 A/cm2, respectively. The GaNAsSb photodiodes exhibit a record pulse response width of only 40.5 ps (full width at half maximum) corresponding to a 4.5 GHz bandwidth. [ABSTRACT FROM AUTHOR]

A GaAsNSb heterojunction bipolar transistor (HBT) structure was grown by solid source molecular beam epitaxy. The fabricated HBT showed a reduction in the turn-on voltage of ∼195 mV when GaAs0.915N0.005Sb0.08 was used as the base material. The small knee voltage (<1 V) of the GaAsNSb HBT indicates that the current blocking effect is small. Significant gain degradation in the GaAsNSb HBT was observed when the nitrogen (N) composition was increased to 2%. The results show that the dilute nitride GaAsNSb materials have potential for reducing the turn-on voltage in GaAs HBTs. [ABSTRACT FROM AUTHOR]

Abstract: The electrical and optical characteristics of planar non-annealed GaInNAs/GaAs p-i-n photodetector structures with 0.5μm thick GaInNAs i-layer with nitrogen composition higher than 3% and detection wavelength up to 1.35μm are reported. Soft-breakdown behavior in the reverse biased characteristic was observed under non-illuminated condition. Analysis of the reverse biased current dependence on detector diameter under non-illuminated condition shows a more significant contribution from the bulk generation current compared to surface recombination current. Under forward bias, the ideality factor value of 1.35 is found to be temperature independent. This suggests that the recombination current in the depletion region contributes significantly to the forward biased current besides the diffusion current. Low-temperature (4K) photoluminescence (PL) from the GaInNAs layer shows an emission peak at λ =1.29μm. From curve fitting of the photoresponsivity spectrum, the room-temperature bandgap of E g,RT =0.92eV (or λ =1.35μm) is deduced. The room-temperature photoresponsivity spectrum shows a broad wavelength detection range of up to λ =1.4μm. [Copyright &y& Elsevier]

The effects of doping antimony (Sb) to dilute GaAsNx (x=0.4%) grown on GaAs by molecular bean epitaxy are investigated. A transition region was found at 5×10−9

We report the formation of interfacial misfit dislocation found in GaSb layers grown on (001) GaAs substrates using anion exchange process at different growth temperatures. An in-situ reflection high-energy electron diffraction (RHEED) in conjunction with transmission electron microscopy (TEM), atomic force spectroscopy (AFM) and X-ray diffraction (XRD) analysis was applied to investigate the relations between substrate temperature, As to Sb anion exchange, the changes in threading dislocation density and the growth kinetics of the GaSb/GaAs heteroepitaxy system. A GaSb layer grown at 450 °C exhibited the lowest threading dislocation density. Our results provide further understanding of the dominant substrate temperature-dependent growth mechanisms that can affect threading dislocation in the GaSb on a GaAs heteroepitaxy system, which uses anion exchange process to facilitate the formation of interfacial misfit dislocation. [ABSTRACT FROM AUTHOR]