Showing papers in "Journal of Semiconductors in 2015"

Properties of n-type SnO2 semiconductor prepared by spray ultrasonic technique for photovoltaic applications

Abstract: Transparent conducting n-type SnO2 semiconductor films were fabricated by employing an inexpensive, simplified spray ultrasonic technique using an ultrasonic generator at deferent substrate temperatures (300, 350, 400, 450 and 500 °C). The structural studies reveal that the SnO2 films are polycrystalline at 350, 400, 450, 500 °C with preferential orientation along the (200) and (101) planes, and amorphous at 300 °C. The crystallite size of the films was found to be in the range of 20.9–72.2 nm. The optical transmittance in the visible range and the optical band gap are 80% and 3.9 eV respectively. The films thicknesses were varied between 466 and 1840 nm. The resistivity was found between 1.6 and 4 × 10−2 Ωcm. This simplified ultrasonic spray technique may be considered as a promising alternative to a conventional spray for the massive production of economic SnO2 films for solar cells, sensors and opto-electronic applications.

Theoretical study of defect impact on two-dimensional MoS2

Abstract: Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2−xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.

A comparison between different ohmic contacts for ZnO thin films

Abstract: There are several metals that form ohmic contacts for ZnO thin films, such as copper, aluminum and silver. The aim of this work is to make a comparison between these ohmic contacts. To achieve this purpose, polycrystalline ZnO thin films were prepared by the spray pyrolysis technique, and characterized by the I–V measurements at room temperature. Two strips of each metal were thermally evaporated on the surface of the film and measurements were first recorded in the dark and room light, then in the dark before and after annealing for Al, which was found to be the best in the set. Films with aluminum contacts gave the smallest resistivity, best ohmicity and they are slightly affected by light as required. On the other hand, copper was found to be the worst, and films with copper contacts gave the largest resistivity, worst ohmicity and they are the most affected by light. Annealing improved the aluminum contacts due to alloying and doping.

Free-space communication based on quantum cascade laser

Abstract: A free-space communication based on a mid-infrared quantum cascade laser (QCL) is presented. A room-temperature continuous-wave distributed-feedback (DFB) QCL combined with a mid-infrared detector comprise the basic unit of the communication system. Sinusoidal signals at a highest frequency of 40 MHz and modulated video signals with a carrier frequency of 30 MHz were successfully transmitted with this experimental setup. Our research has provided a proof-of-concept demonstration of space optical communication application with QCL. The highest operation frequency of our setup was determined by the circuit-limited modulation bandwidth. A high performance communication system can be obtained with improved modulation circuit system.

ZnS thin films deposition by thermal evaporation for photovoltaic applications

Abstract: ZnS thin films were deposited on glass substrates by thermal evaporation from millimetric crystals of ZnS. The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV–VIS spectroscopy. The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation. The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8. The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells.

Temperature effect on hetero structure junctionless tunnel FET

Abstract: For the first time, we investigate the temperature effect on AlGaAs/Si based hetero-structure junctionless double gate tunnel field effect transistor. Since junctionless tunnel FET is an alternative substitute device for ultra scaled deep-submicron CMOS technology, having very good device characteristics such as an improved subthreshold slope (< 60 mV/decade at 300 K) and very small static leakage currents. The improved subthreshold slope and static leakage current confirms that it will be helpful for the development of future low power switching circuits. The 2-D computer based simulation results show that OFF-state leakage current is almost temperature independent for the proposed device structure.

Effect of Co doping on structural, optical, electrical and thermal properties of nanostructured ZnO thin films

Abstract: Nanocrystalline Zn1−xCoxO (where x varies from 0 to 004 in steps of 001) thin films were deposited onto glass substrate by the spray pyrolysis technique at a substrate temperature of 350 °C The X-ray diffraction patterns confirm the formation of hexagonal wurtzite structure The crystal grain size of these films was found to be in the range of 11−36 nm The scanning electron micrographs show a highly crystalline nanostructure with different morphologies including rope-like morphology for undoped ZnO and nanowalls and semispherical morphology for Co-doped ZnO The transmittance increases with increasing Co doping The optical absorption edge is observed in the transmittance spectra from 530 to 692 nm, which is due to the Co2+ absorption bands corresponding to intraionic d-d* shifts The direct and indirect optical band gap energies decrease from 305 to 275 eV and 318 to 300 eV, respectively for 4 mol% Co doping The electrical conductivity increases with increasing both the Co doping and temperature, indicating the semiconducting nature of these films The temperature dependence thermal electromotive force measurement indicates that both undoped and Co-doped ZnO thin films show p-type semiconducting behavior near room temperature This behavior dies out beyond 313 K and they become n-type semiconductors

Numerical investigation of a double-junction a:SiGe thin-film solar cell including the multi-trench region

Abstract: We present a new approach based on the multi-trench technique to improve the electrical performances, which are the fill factor and the electrical efficiency. The key idea behind this approach is to introduce a new multi-trench region in the intrinsic layer, in order to modulate the total resistance of the solar cell. Based on 2-D numerical investigation and optimization of amorphous SiGe double-junction (a-Si:H/a-SiGe:H) thin film solar cells, in the present paper numerical models of electrical and optical parameters are developed to explain the impact of the multi-trench technique on the improvement of the double-junction solar cell electrical behavior for high performance photovoltaic applications. In this context, electrical characteristics of the proposed design are analyzed and compared with conventional amorphous silicon double-junction thin-film solar cells.

Correlation between the structural, morphological, optical, and electrical properties of In 2 O 3 thin films obtained by an ultrasonic spray CVD process

Abstract: Indium oxide (In 2 O 3 ) thin films are successfully deposited on glass substrate at different deposition times by an ultrasonic spray technique using Indium chloride as the precursor solution; the physical properties of these films are characterized by XRD, SEM, and UV-visible. XRD analysis showed that the films are polycrystalline in nature having a cubic crystal structure and symmetry space group Ia3 with a preferred grain orientation along the (222) plane when the deposition time changes from 4 to 10 min, but when the deposition time equals 13 min we found that the majority of grains preferred the (400) plane. The surface morphology of the In 2 O 3 thin films revealed that the shape of grains changes with the change of the preferential growth orientation. The transmittance improvement of In 2 O 3 films was closely related to the good crystalline quality of the films. The optical gap energy is found to increase from 3.46 to 3.79 eV with the increasing of deposition time from 4 to 13 min. The film thickness was varied between 395 and 725 nm. The film grown at 13 min is found to exhibit low resistivity (10 -2 Ω·cm), and relatively high transmittance (~ 93%).

Modelling of nanostructured TiO2-based memristors

Abstract: The fourth fundamental circuit element memristor completes the missing link between charge and magnetic flux. It consists of the function of the resistor as well as memory in nonlinear fashion. The property of the memristor depends on the magnitude and direction of applied potential. This unique property makes it the primitive building block for many applications such as resistive memories, soft computing, neuromorphic systems and chaotic circuits etc. In this paper we report TiO2-based nanostructured memristor modelling. The present memristor model is constructed in MATLAB environment with consideration of the linear drift model of memristor. The result obtained from the linear drift model is well matched with earlier reported results by other research groups.

Electronic, optical, and mechanical properties of Cu 2 ZnSnS 4 with four crystal structures

Abstract: The structural, electronic, optical, and mechanical properties of Cu2ZnSnS4 with four crystal structures are calculated using the density functional theory. No significant difference is observed between the calculated optical and mechanical properties of the considered four crystal structures. The calculated results are in agreement with available reported experimental data. According to the calculated results, the fundamental band gap of Cu2ZnSnS4 is mainly determined by the bandwidth of the isolated conduction band. The effective-mass of carriers of Cu2ZnSnS4 are very small, especially the effective-mass of electrons on the bottom of the conduction band of zincblende-derived Cu2ZnSnS4. Using the calculated elastic constants matrix, the Born stability criteria is shown to be satisfied, and the high B/G ratio indicates that Cu2ZnSnS4 is prone to ductile behavior.

A novel SOI pressure sensor for high temperature application

Abstract: The silicon on insulator (SOI) high temperature pressure sensor is a novel pressure sensor with high-performance and high-quality. A structure of a SOI high-temperature pressure sensor is presented in this paper. The key factors including doping concentration and power are analyzed. The process of the sensor is designed with the critical process parameters set appropriately. The test result at room temperature and high temperature shows that nonlinear error below is 0.1%, and hysteresis is less than 0.5%. High temperature measuring results show that the sensor can be used for from room temperature to 350 °C in harsh environments. It offers a reference for the development of high temperature piezoresistive pressure sensors.

Inhomogeneous barrier height effect on the current-voltage characteristics of an Au/n-InP Schottky diode

Abstract: We report the current–voltage (I–V) characteristics of the Schottky diode (Au/n-InP) as a function of temperature. The SILVACO-TCAD numerical simulator is used to calculate the I–V characteristic in the temperature range of 280–400 K. This is to study the effect of temperature on the I–V curves and assess the main parameters that characterize the Schottky diode such as the ideality factor, the height of the barrier and the series resistance. The I–V characteristics are analyzed on the basis of standard thermionic emission (TE) theory and the inhomogeneous barrier heights (BHs) assuming a Gaussian distribution. It is shown that the ideality factor decreases while the barrier height increases with increasing temperature, on the basis of TE theory. Furthermore, the homogeneous BH value of approximately 0.524 eV for the device has been obtained from the linear relationship between the temperature-dependent experimentally effective BHs and ideality factors. The modified Richardson plot, according to the inhomogeneity of the BHs, has a good linearity over the temperature range. The evaluated Richardson constant A* was 10.32 Acm−2K−2, which is close to the theoretical value of 9.4 Acm−2K−2 for n-InP. The temperature dependence of the I–V characteristics of the Au/n-InP Schottky diode have been successfully explained on the basis of the thermionic emission (TE) mechanism with a Gaussian distribution of the Schottky barrier heights (SBHs). Simulated I–V characteristics are in good agreement with the measurements [Korucu D, Mammadov T S. J Optoelectronics Advanced Materials, 2012, 14: 41]. The barrier height obtained using Gaussian Schottky barrier distribution is 0.52 eV, which is about half the band gap of InP.

Semiconducting properties of aluminum-doped ZnO thin films grown by spray pyrolysis technique

Abstract: Highly transparent and preferential c-axis oriented nanocrystalline undoped and Al doped zinc oxide (AZO) thin films have been deposited onto amorphous glass substrate by spray pyrolysis. The XRD studies reveal that AZO with a hexagonal (wurtzite) crystal structure having (002) preferred orientation is formed. The atomic force microscope (AFM) shows uniform surface topography. The optical band gap values of undoped and AZO thin films were changed from 3.34 to 3.35 eV. The band gap energy and photoluminescence are found to depend on the Al doping. Thermoelectric power measurement shows film having n-type in nature. Dielectric constant and loss (tan δ) were found to be frequency dependent. Interparticle interactions in the deposited films are studied by complex impendence spectroscopy.

Simulation of a high-efficiency silicon-based heterojunction solar cell

Abstract: The basic parameters of a-Si:H/c-Si heterojunction solar cells, such as layer thickness, doping concentration, a-Si:H/c-Si interface defect density, and the work functions of the transparent conducting oxide (TCO) and back surface field (BSF) layer, are crucial factors that influence the carrier transport properties and the efficiency of the solar cells. The correlations between the carrier transport properties and these parameters and the performance of a-Si:H/c-Si heterojunction solar cells were investigated using the AFORS-HET program. Through the analysis and optimization of a TCO/n-a-Si:H/i-a-Si:H/p-c-Si/p+-a-Si:H/Ag solar cell, a photoelectric conversion efficiency of 27.07% (VOC) 749 mV, JSC: 42.86 mA/cm2, FF: 84.33%) was obtained through simulation. An in-depth understanding of the transport properties can help to improve the efficiency of a-Si:H/c-Si heterojunction solar cells, and provide useful guidance for actual heterojunction with intrinsic thin layer (HIT) solar cell manufacturing.

Oriented colloidal-crystal thin films of polystyrene spheres via spin coating

Abstract: We developed a simple and inexpensive synthesis of a large-scale close-packed monolayer of polystyrene sphere arrays, which have a variety of applications. The influence of three step spin speeds, spinning time, solution quantity and relative humidity is studied in order to achieve a large area close-packed monolayer. A relatively high surface coverage and uniform monolayer of PS spheres in the range of 85%–90% are achieved by appropriate control of the preparative parameters. Also the effect of the oxygen plasma etching process on the reduction of PS spheres has been studied. We conclude that it can be useful in industrial applications, because of the fabrication speed, surface coverage, control over PS spheres and cost of the process.

Temperature sensor based on composite film of vanadium complex (VO 2 (3-fl)) and CNT

Abstract: A vanadium complex (VO2(3-fl)) and CNT composite film based temperature sensor is reported in this study. Surface-type silver electrodes were deposited on the glass substrates. A thin film of VO2(3-fl) and CNT composite was coated as a temperature-sensing material on the top of the pre-patterned Ag electrodes. The temperature-sensing principle of the sensor was based on the conductivity change of the coated sensing element upon heating or cooling processes. DC and AC (100 Hz) resistances of the temperature sensor decreased quasilinearly with increasing the temperature in the range of 25–80 °C. The overall resistance of the sensor decreases by 1.8–2.1 and 1.9–2.0 times at DC and AC voltage, respectively. The resistance temperature coefficients of the sensor were in the range of −(0.9–1.3)% and −(1.1–1.3)% at DC and AC voltage, respectively. The properties of the sensor studied in this work, make it beneficial to be used in the instruments for environmental monitoring of temperature.

The calculation of band gap energy in zinc oxide films

Abstract: We investigated the optical properties of undoped zinc oxide thin films as the n-type semiconductor; the thin films were deposited at different precursor molarities by ultrasonic spray and spray pyrolysis techniques. The thin films were deposited at different substrate temperatures ranging between 200 and 500 ℃. In this paper, we present a new approach to control the optical gap energy of ZnO thin films by concentration of the ZnO solution and substrate temperatures from experimental data, which were published in international journals. The model proposed to calculate the band gap energy with the Urbach energy was investigated. The relation between the experimental data and theoretical calculation suggests that the band gap energies are predominantly estimated by the Urbach energies, film transparency, and concentration of the ZnO solution and substrate temperatures. The measurements by these proposal models are in qualitative agreements with the experimental data; the correlation coefficient values were varied in the range 0.96–0.99999, indicating high quality representation of data based on Equation (2), so that the relative errors of all calculation are smaller than 4%. Thus, one can suppose that the undoped ZnO thin films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition and contained higher optical band gap energy.

GaN HEMT with AlGaN back barrier for high power MMIC switch application

Abstract: 0.25 μm GaN HEMT with AlGaN back barrier for high power switch application has been presented. By introducing AlGaN back barrier, the buffer layer breakdown voltage for the metal-organic chemical vapor deposited AlGaN/GaN hetero-structure on 3-inch SiC substrate showed a considerable increment, which was nearly 4× and 2× of that for the conventional GaN buffer layer and GaN buffer layer with Fe doped, respectively. GaN switch HEMTs with source to drain spacing of 2, 2.5, 3, 3.5 and 4 μm were fabricated on the AlGaN/GaN epitaxial material with AlGaN back barrier and estimated off state power handling for the GaN switch HEMTs were 25.0, 46.2, 64.0, 79.2, and 88.4 W, respectively. A demonstrator DC-12 GHz GaN SPDT MMIC switch was designed in reflective series-shunt-shunt configuration based on the GaN HEMT, with a source to drain spacing of 2.5 μm. The developed SPDT MMIC switch showed a maximum insertion loss of 1.0 dB and a minimum isolation of 30 dB at a frequency range of DC-12 GHz. A power handling capability of 44.1 dBm was achieved at 10 GHz for the MMIC switch with continuous wave power compression measurement.

The geometric resistivity correction factor for several geometrical samples

Abstract: This paper reviews the geometric resistivity correction factor of the 4-point probe DC electrical conductivity measurement method using several geometrical samples. During the review of the literature, only the articles that include the effect of geometry on resistivity calculation were considered. Combinations of equations used for various geometries were also given. Mathematical equations were given in the text without details. Expressions for the most commonly used geometries were presented in a table for easy reference.

RuO2/MnO2 composite materials for high-performance supercapacitor electrodes

Abstract: Ruthenium oxide and manganese oxide nanomaterials were respectively prepared by a sol–gel process and hydrothermal synthesis method. The morphologies and microstructures of the composite nanomaterials were characterized by SEM and XRD. Based on the cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge–discharge techniques, the performances of the electrodes were investigated. The results show that the composite of manganese oxide and ruthenium oxide is beneficial to improve the impedance characteristic. The electrode with 60% (mass ratio) manganese oxide has a high specific capacitance of 438 F/g and a lower inner resistance of 0.304 Ω using 38% (mass ratio) H2SO4 solution. The capacitance retention of RuO2/MnO2 composite electrode was 92.5% after 300 cycles.

Deposition and doping of CdS/CdTe thin film solar cells

Abstract: 1% oxygen is incorporated into both CdS and CdTe layers through RF sputtering of CdS/CdTe thin film solar cells. The optical and electrical parameters of the oxygenated and O2-free devices are compared after CdCl2 treatment and annealing in ambient Ar and/or air. The effects of ambient annealing on the electrical and optical properties of the films are investigated using current—voltage characterization, field emission scanning electron microscopy, X-ray diffraction, and optical transmission spectroscopy. The 1% oxygen content can slightly increase the grain size while the crystallinity does not change. Annealing in ambient Ar can increase the transmission rate of the oxygenated devices.

Hydrolysis preparation of the compact TiO 2 layer using metastable TiCl 4 isopropanol/water solution for inorganic-organic hybrid heterojunction perovskite solar cells

Abstract: A hydrolysis process was applied to prepare the compact TiO2 layer using the fresh metastable TiCl4 isopropanol/water solution as the precursor solution for the preparation of the inorganic–organic hybrid heterojunction perovskite solar cells. The optimal compact TiO2 layer prepared from the aqueous solution of 2 mol/L TiCl4 diluted in isopropanol at 1 : 3 by volume as precursor solution was uniform and with a film thickness of 126 nm. The corresponding perovskite solar cell gave a photovoltaic conversion efficiency of 10.61%.

Design and fabrication of a 3.3 kV 4H-SiC MOSFET

Abstract: A 4H-SiC MOSFET with breakdown voltage higher than 3300 V has been successfully designed and fabricated. Numerical simulations have been performed to optimize the parameters of the drift layer and DMOSFET cell structure of active area. The n-type epilayer is 33μm thick with a doping of 2.5 × 1015 cm-3. The devices were fabricated with a floating guard ring edge termination. The drain current Id = 5 A at Vg = 20 V, corresponding to Vd = 2.5 V.

Modeling and simulation of single-event effect in CMOS circuit

Abstract: This paper reviews the status of research in modeling and simulation of single-event effects (SEE) in digital devices and integrated circuits. After introducing a brief historical overview of SEE simulation, different level simulation approaches of SEE are detailed, including material-level physical simulation where two primary methods by which ionizing radiation releases charge in a semiconductor device (direct ionization and indirect ionization) are introduced, device-level simulation where the main emerging physical phenomena affecting nanometer devices (bipolar transistor effect, charge sharing effect) and the methods envisaged for taking them into account are focused on, and circuit-level simulation where the methods for predicting single-event response about the production and propagation of single-event transients (SETs) in sequential and combinatorial logic are detailed, as well as the soft error rate trends with scaling are particularly addressed.

High performance AlGaN/GaN HEMTs with AlN/SiN x passivation

Abstract: AlGaN/GaN high electron-mobility transistors (HEMTs) with 5 nm AlN passivation by plasma enhanced atomic layer deposition (PEALD) were fabricated, covered by 50 nm SiNx which was grown by plasma enhanced chemical vapor deposition (PECVD). With PEALD AlN passivation, current collapse was suppressed more effectively and the devices show better subthreshold characteristics. Moreover, the insertion of AlN increased the RF transconductance, which lead to a higher cut-off frequency. Temperature dependence of DC characteristics demonstrated that the degradations of drain current and maximum transconductance at elevated temperatures for the AlN/SiNx passivated devices were much smaller compared with the devices with SiNx passivation, indicating that PEALD AlN passivation can improve the high temperature operation of the AlGaN/GaN HEMTs.

Influence of growth rate on the carbon contamination and luminescence of GaN grown on silicon

Abstract: The unintentional carbon doping concentration of GaN films grown by low pressure metal organic chemical vapor deposition (LP-MOCVD) depends strongly on the growth rate. The concentration of carbon is varied from 2.9 × 10 17 to 5.7 × 10 18 cm -3 when the growth rate increases from 2.0 to 7.2 μ m/h, as detected by secondary ion mass spectroscopy. It is shown that the presence of N vacancies give rises to high carbon concentration. We show that a reduction of the carbon concentration by one order of magnitude compared to the regular sample with nearly same growth rate can be achieved by operating at an extremely high NH 3 partial pressure during growth. The intensity ratios of yellow and blue luminescence to band edge luminescence in the samples are found to depend significantly on carbon concentration. The present results demonstrate direct and quantitative evidence that the carbon related defects are the origin of yellow and blue luminescence.

Transparent and conductive PEDOT:PSS/Ag NW/PEDOT:PSS hybrid films prepared by spin-coating at room temperature

Abstract: PEDOT:PSS/Ag NW/PEDOT:PSS hybrid films were deposited on PET substrates by the spin coating technique at room temperature. The optical transmittance, sheet resistance, crystallization and surface morphology were characterized by using the double beam spectrophotometer, Hall effect system, X-ray diffractometer and field emission scanning electron microscopy. XRD patterns of the hybrid films display characteristic diffraction peaks of Ag (111) and Ag (200), and the Ag NW networks have a polycrystalline structure with a Ag (111) preferred orientation. A high transmittance of 83.95% at the 550 nm wavelength and a low sheet resistance of 21.98 Ω/ are achieved for 3-PEDOT:PSS/5-Ag NW/3-PEDOT:PSS hybrid films.

Non-ionic surfactant on particles removal in post-CMP cleaning

Abstract: The effect of a non-ionic surfactant on particles removal in post-CMP cleaning was investigated. By changing the concentration of the non-ionic surfactant, a series of experiments were performed on the 12 inch Cu pattern wafers in order to determine the best cleaning results. Then the effect of the surfactant on the reduction of defects and the removal of particles was discussed in this paper. What is more, the negative effect of a non-ionic surfactant was also discussed. Based on the experiment results, it is concluded that the non-ionic surfactant could cause good and ill effects at different concentrations in the post-CMP cleaning process. This understanding will serve as a guide to how much surfactant should be added in order to achieve excellent cleaning performance.

The design and analysis of a MEMS electrothermal actuator

Abstract: This paper introduces a type of out-of-plane microelectrothermal actuator, which is based on the principle of bimetal film thermal expansion in the fuse. A polymer SU-8 material and nickel are used as the functional and structural materials of the actuator. Through heating the resistance wire using electricity, the actuator produces out-of-plane motion in the perpendicular axial direction of the device and the bias layer contact with the substrate, completing signal output. Using Coventorware software to establish the three-dimensional model, the geometric structure is optimized and the electrothermal capabilities are determined theoretically. From electrothermal analysis, the actuator's displacement is 18 μm and the temperature rises from 300 to 440 K under a voltage of 5 V and the response time is 5 ms. The actuator's displacement is 20 μm under a 100000 m/s2 acceleration in the accelerating field. In the coupled field, applying a 3 V voltage, the initial temperature is 300 K, while the acceleration is 50000 m/s2, the driving displacement of the actuator is 23 μm, and temperature rises to 400 K. Finally, through checking the stress in different field sources, the maximum stress of the actuator is smaller than the allowable stress of nickel. The results show that the electrothermal actuator has high reliability.