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Abstract: Chemically conformal deposition of SrTiO3 (STO) thin films was successfully achieved by ALD using conventional metal organic precursors and remote-plasma activated H2O. It was found that the ALD behavior of the STO film was critically dependent on the Sr(thd)2 source bubbling temperature. When the Sr-source bubbling temperature was <∼200 °C (Sr(thd)2 melting temperature), the deposition proceeded in a genuine ALD mode and stoichiometric STO films were deposited with a good process reliability. Relatively good electrical properties were obtained from a planar capacitor structure with Pt top and Ru bottom electrodes. A 19.5-nm-thick STO film showed an equivalent oxide thickness (EOT) of 0.8 nm and a leakage current density of 1.98×10−6 A/cm2 at 1V after post-annealing. [Copyright &y& Elsevier]

Thermal stability and interfacial charge trap properties of the multi-metal (Ir/Pt/Au) top electrode of a metal–insulator–metal cathode for field emission display applications were examined. The thin (∼5 nm) multi-metal electrode did not show sufficient thermal stability during the post-annealing stage, which is needed to obtain good emission properties of the cathode, due to inter-diffusion and agglomeration of the layers. Reactively sputtered IrO2 thin films as the top electrode were examined considering their excellent thermal stability and low work function. However, the proper sputtering conditions of thin IrO2 (<10 nm) films were different from those of thick films (>100 nm) and should be optimized again due to the serious resputtering of the substrate at the initial deposition stage. Increasing the oxygen concentration (25%) during sputtering, which is the condition that results in a non-uniform film when the film is thick (>100 nm), was essential to ensure that the film was a well oxidized IrO2 when the film was very thin (<10 nm). Excellent thermal stability in terms of the non-varying resistivity and surface roughness of the 8-nm-thick IrO2 films compared to the multi-metal electrode film were confirmed. [Copyright &y& Elsevier]

The resistive switching (RS) behavior of a gallium oxide (Ga 2 O 3) thin film for use in resistive random access memory (RRAM) was investigated. Ta/Ga 2 O 3 /Pt memory devices exhibited favorable RS behavior, such as a small distribution of switching parameters and switching cycles of more than 3 × 106. X-ray photoelectron spectroscopy and the current transport mechanism indicated that that the RS behavior was attributed to the local variation on the Schottky barrier near the Pt electrode interface due to oxygen vacancies. A hybrid system for self-powered data storage and deletion was built by combining the RRAM device with a commercial Pb(Zr 1-x Ti x)O 3 piezoelectric ceramic as a pressure sensor/power generator. The excellent anti-interference and reuse performance of the system indicated promising potential for the application of this memory device. [ABSTRACT FROM AUTHOR]

Abstract: The electronic structure of amorphous semiconductor InGaO3(ZnO)0.5 thin films, which were deposited by radio-frequency magnetron sputtering process, was investigated using X-ray photoelectron spectroscopy and O K-edge X-ray absorption spectroscopy. The overall features of the valence and conduction bands were analyzed by comparing with the spectra of Ga2O3, In2O3, and ZnO films. The valence and conduction band edges are mainly composed of O 2p and In 5sp states, respectively. The bandgap of the films determined by spectroscopic ellipsometry was approximately 3.2 eV. Further, it is found that the introduction of oxygen gas during the sputter-deposition does not induce significant variations in the chemical states and band structure. [Copyright &y& Elsevier]

Atomic layer deposition (ALD) on Ta-doped SnO 2 thin films is proposed as a methodology for the fabrication of capacitor electrodes, for application in dynamic random-access memories (DRAMs). In ALD of doped materials, dopant concentration gradients inevitably occur due to the cyclic process-based characteristics of ALD. In this study, the dopant distribution improves drastically by the decrease in the growth per cycle of TaO x ALD. The modified ALD recipe exploits the low reactivity between Ta and Sn precursors to facilitate a reduction in the growth per cycle. The Ta-doped SnO 2 films grown based on this modified ALD recipe exhibit improved crystallinity and conductivity. The ALD process yields excellent conformality of the Ta-doped SnO 2 film over a hole structure with a high aspect ratio of ~10, both in terms of physical thickness and composition. Additionally, the Ta-doped SnO 2 films serve as a template for the overgrowing dielectric TiO 2 film, which induces the formation of a high-temperature phase with a high dielectric constant, rutile TiO 2 , and exhibit excellent thermal stability even after annealing at 400 °C in forming gas atmosphere. These findings demonstrate that the proposed methodology for the growth of Ta-doped SnO 2 can facilitate the fabrication of capacitor electrodes for application in DRAMs. Unlabelled Image • A new ALD process of Ta-doped SnO 2 films is demonstrated. • Potential applications include use as reduction-resistant capacitor electrode. • Dopant distribution improves by decrease in the growth per cycle of TaO x ALD. • Films reveal ease of formation of high-k rutile TiO 2 and excellent thermal stability. [ABSTRACT FROM AUTHOR]

The presence of an AlN interfacial layer in high-k/In 0.53 Ga 0.47 As gate stacks improves the interfacial properties and enhances the electrical performance of devices. However, pure AlN is rarely grown by atomic layer deposition (ALD) because of the low reactivity of NH 3 toward the common Al-precursor and the predisposition to oxidation of the grown AlN layer. Although a plasma-enhanced ALD technique significantly suppresses the oxygen content in the grown AlN layer, the deterioration of the interface properties by plasma-damage is a critical issue. In this work, an AlON interlayer was engineered by optimizing the NH 3 feeding time in thermal ALD to improve the interface quality in Al 2 O 3 /AlON/In 0.53 Ga 0.47 As capacitors. It was determined that a mere increase in the NH 3 feeding time during the ALD of the AlON film resulted in a higher nitrogen incorporation into the AlON interlayer, leading to a reduction in the interface trap density. Furthermore, the out-diffusion of elements from the In 0.53 Ga 0.47 As layer was effectively suppressed by increasing the NH 3 feeding time. This work demonstrates that simple process optimization can improve the interface quality in high-k/In 0.53 Ga 0.47 As gate stacks without the use of any plasma-activated nitrogen source. [ABSTRACT FROM AUTHOR]

This paper investigates the effect of an oxygen (O 2 ) plasma treatment on multi-layer tungsten diselenide (WSe 2 ) field-effect transistor (FET) by forming tungsten trioxide (WO 3 ) layers. Palladium (Pd), which is known to form an Ohmic contact with WSe 2 , is used for the source and drain (S/D) contact electrodes as a control group for metal variables. And then, Nickel (Ni), which is thought to form a Schottky contact with WSe 2 experimentally, is used as an experimental group. For both cases of the control group and the experimental group, the electrical characteristics including drain current ( I D ), on/off ratio ( I ON / I OFF ), subthreshold swing ( SS ) and field effect mobility ( μ eff ) are analyzed according to the presence or absence of WO 3 . In case of adopting the WO 3 contact layer between the WSe 2 and the Ni for the S/D contact electrode, we observe a remarkable improvement in I D , I ON / I OFF , μ eff , and SS compared to the case without the WO 3 contact layer. The analyzed electrical characteristics show that an efficient hole-injection contact was achieved for the multi-layer WSe 2 FET by the O 2 plasma treatment, which leads to the formation of an Ohmic-like contact at an electrode/WSe 2 interface. [ABSTRACT FROM AUTHOR]

The process sequence and device performances of the three-dimensional tri-gate field effect transistor (TGFET) were reported, where a fin-shaped Si channel with a 20 nm channel width and an 80 nm fin height was fabricated using the conventional i -line stepper, assisted by the double hard mask step-down (DHMSD) lithography process. The channel length was 150 nm. An atomic-layer-deposited Al 2 O 3 film with an equivalent oxide thickness of 1.9 nm and a TiN layer grown through another atomic layer deposition process were adopted as the high-k and metal gate, respectively, using the dummy gate process. The device performance was compared with that of the planar FET simultaneously fabricated on the same Si wafer. The ion implantation and Ni-silicide processes were also optimized for this process sequence. Both n- and p-type devices were fabricated. The TGFET showed a high on/off current ratio of ~ 10 6 , a low subthreshold swing of 105 mV/dec for the n-type device, and a small drain-induced barrier lowering of 30 mV for the n-type device, which were remarkably improved device performances compared with the planar FET device. These improvements were due to the improvement of the electrostatic control of the fin-shaped channel by the tri-gates, which coincides with the theoretical expectation and previous experiment results. Nevertheless, the p-type devices showed inferior performances compared with the n-type devices due to the excessive dopant diffusion from the source and drain regions into the channel. [ABSTRACT FROM AUTHOR]

A metal-oxide-semiconductor field-effect transistor (MOSFET)-based gas sensor having a floating gate (FG) is fabricated and its sensing property is characterized. The gas sensor has 10 nm thick ZnO as a sensing layer prepared by atomic layer deposition (ALD). The FG, the sensing layer and the control gate (CG) are formed horizontally so that diverse sensing materials can be applied to the structure of the sensor without contamination. The gas-sensing performance of the sensor is investigated for seven target gases. Drain currents in NO 2 and H 2 S ambiences are changed by 176% and 58%, respectively, for given NO 2 (20 ppm) and H 2 S (20 ppm) concentrations. Whereas the changes of drain current for NH 3 , SO 2 , CO 2 , CH 4 and C 3 H 8 gases are less than 5%. Response and recovery times for NO 2 are 90 s and 580 s, respectively, at 180 °C. The responses with working temperature and gas concentration are also studied. The sensing mechanisms for NO 2 and H 2 S gases are explained. [ABSTRACT FROM AUTHOR]

[Display omitted] • P5Grand , a program for calculating the properties of pseudobinary systems, is introduced. • Grand canonical partition function is efficiently calculated using P5Grand. • (In,Ga)As bandgap is predicted using P5Grand from both DFT and cluster expansion results. • Comparison of experimental and predicted bandgap confirms the reliability of P5Grand. We introduce introduces an open-source program for calculating the properties of solid solutions, " P ython P ackage for P roperty P rediction of P seudobinary systems using Grand canonical ensemble" ( P5Grand ). P5Grand uses two main strategies to improve calculation efficiency: random configuration sampling and separate calculations of the strain energy induced by local compositional fluctuations within the grand canonical ensemble. P5Grand can efficiently calculate thermodynamic properties and any properties of interest for arbitrary solid solution as a function of temperature and composition using two input files. The efficiency of P5Grand is demonstrated by the bandgap prediction of (In,Ga)As. [ABSTRACT FROM AUTHOR]

Surface sulfur (S) passivation on InP substrate was performed using a dry process – rapid thermal annealing under H 2 S atmosphere for III–V compound-semiconductor-based devices. The electrical properties of metal-oxide-semiconductor capacitor fabricated with atomic-layer-deposited HfO 2 film as a gate insulator were examined, and were compared with the similar devices with S passivation using a wet process – (NH 4 ) 2 S solution treatment. The H 2 S annealing provided solid S passivation with the strong resistance against oxidation compared with the (NH 4 ) 2 S solution treatment, although S profiles at the interface of HfO 2 /InP were similar. The decrease in electrical thickness of the gate insulator by S passivation was similar for both methods. However, the H 2 S annealing was more effective to suppress interface state density near the valence band edge, because thermal energy during the annealing resulted in stronger S bonding and InP surface reconstruction. Moreover, the flatband voltage shift by constant voltage stress was lower for the device with H 2 S annealing. [ABSTRACT FROM AUTHOR]

SrTiO 3 (STO) thin films, grown by atomic layer deposition (ALD), were studied for capacitors in dynamic random access memory. The STO ALD process consisted of two steps: the growth of seed layer followed by a rapid thermal annealing (RTA) process at 650 °C to crystallize it, and the deposition of the main layer on top of the seed layer at 370 °C to induce the in-situ crystallization. During single cooling process after the RTA of the seed layer, voids and nano-cracks were formed due to the thermal expansion mismatch between STO film and Si substrate. This problem was well mitigated by adopting the stepwise cooling process, wherein the holding time of 30 s at 500, 350, and 200 °C suppressed the defect formation in the seed layer. Therefore, the main layer grown on that seed layer showed an improved microstructure with a high bulk dielectric constant of 135. However, the increase in total annealing time degraded the interface quality between the STO and the bottom electrode, which finally worsened the insulating property. As a result, the minimum equivalent oxide thicknesses with low leakage current densities (< 10 − 7 A/cm 2 at 0.8 V) for the single and stepwise cooling processes were 0.39 nm and 0.46 nm, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composition- and configuration-dependent bandgap of Ga(As,Sb) is calculated. • Cluster expansion and ab initio thermodynamics are combined to examine bandgap. • Inverse relationship between the bandgap and energetic stability is found. • Average bandgap for a given composition decreases with increasing temperature. • Predicted bandgap shows a feasible agreement with experiments. The composition- and configuration-dependent bandgaps of pseudobinary Ga(As,Sb) are examined by the cluster expansion method and statistical thermodynamics based on density functional theory. The bandgaps and energetic stability of 330,000 configurations in the entire composition range show a consistent inverse relationship, in that a configuration with lower energy has a higher bandgap for a given composition. This inverse relation can be deduced from the opposite signs of effective cluster interaction coefficients for bandgap and energy, and can be quantified by the correlations of properties with short-range order parameters. The bandgap of GaAs 0.5 Sb 0.5 varies from 0.02 to 0.93 eV depending on the atomic configuration, which suggests another tremendous chance to tune the bandgap by the configuration control. The average bandgap of a certain composition, calculated by the ab initio thermodynamics, decreases with increasing temperature. The calculated average bandgap shows feasible agreement with the experimental bandgap, reproducing the bandgap bowing. [ABSTRACT FROM AUTHOR]

Atomic-layer-deposited Al 2 O 3 films were grown on ultrathin-body In 0.53 Ga 0.47 As substrates for III-V compound-semiconductor-based devices. Interface sulfur (S) passivation was performed with wet processing using ammonium sulfide ((NH 4 ) 2 S) solution, and dry processing using post-deposition annealing (PDA) under a H 2 S atmosphere. The PDA under the H 2 S atmosphere resulted in a lower S concentration at the interface and a thicker interfacial layer than the case with (NH 4 ) 2 S wet-treatment. The electrical properties of the device, including the interface property estimated through frequency dispersion in capacitance, were better for (NH 4 ) 2 S wet-treatment than the PDA under a H 2 S atmosphere. They might be improved, however, by optimizing the process conditions of PDA. The PDA under a H 2 S atmosphere following (NH 4 ) 2 S wet-treatment resulted in an increased S concentration at the interface, which improved the electrical properties of the devices. [ABSTRACT FROM AUTHOR]

Highlights: [•] Atomic-layer-deposited HfO2 films grown at extremely low temperatures (≤100°C) were examined. [•] Growth saturation behavior of ALD was observed near to room temperatures. [•] Effects of growth temperatures and O3 concentrations on film properties are reported in detail. [•] Grown HfO2 films exhibited acceptable properties for flexible display and bio-electronic applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] The uncommon aspects of the atomic layer deposition (ALD) reactions are addressed. [•] Influences of metal precursors, non-metal precursors, and substrates are reviewed. [•] Selected functional materials of TiO2, SrTiO3, Ge–Sb–Te, Ru, RuO2, NiO are discussed. [•] Desirable directions for ALD are suggested based on the non-ideal aspects. [Copyright &y& Elsevier]

Abstract: We investigate dielectric properties of rutile TiO2 using various exchange-correlation energy functionals such as local-density approximation (LDA), LDA + U method, and hybrid functionals. It is found that the computed dielectric constants significantly depend on the functional type, which originates from hardening or softening of phonon modes. While LDA provides the best result among the tested functionals, hybrid functionals and LDA + U methods significantly overestimate and underestimate dielectric constants, respectively. The underestimation by LDA + U is most alarming as it is not alleviated by adjusting lattice parameters, which implies that interatomic interactions are fundamentally affected by LDA + U. Furthermore, the LDA + U method also underestimates the dielectric constant of cubic SrTiO3. The present results suggest that special cares are needed in applying the LDA + U method to a system including TiO2 and SrTiO3. [Copyright &y& Elsevier]

Abstract: Ru thin films were grown on polymorphic TiO2 thin film substrates at 230 and 250°C by atomic layer deposition using 2,4-(dimethylpentadienyl)(ethylcyclopentadienyl)Ru and an O2 gas. While the Ru films grown on amorphous and rutile TiO2 substrates showed a relatively long incubation cycle number of approximately 350 and 100 at 230 and 250°C, respectively, the Ru films grown on anatase TiO2 substrates exhibited a significantly shorter incubation delay which was attributed to the catalytic activity of anatase TiO2. This difference in the incubation cycle affected the surface morphology of the Ru films on different TiO2 substrates. [ABSTRACT FROM AUTHOR]

Abstract: The effects of the biaxial compressive strain on the atomic relaxation and the formation energy of a neutral vacancy in Ge were investigated using first-principles calculations. Prior to this, the effects of the supercell size and Brillouin zone sampling were tested. The vacancy formation energy and atomic configuration around a vacancy are strongly affected by the inter-vacancy distance determined by the supercell size, due to the periodic boundary condition. The biaxial compressive strain reduced the formation energy of the vacancy nearly linearly by up to 1.34eV as the magnitude of the biaxial compressive strain increased to the “Ge on Si (GoS)” condition. This was explained in terms of the bond strength characterized by the spatial electron density. The behavior of the vacancy in Ge was also compared with that in Si. [ABSTRACT FROM AUTHOR]

Abstract: Metal-insulator-semiconductor capacitors were fabricated with sputtered ZnO and atomic layer deposited HfO2 as the semiconductor and gate dielectric layers, respectively. From the capacitance–voltage measurements, it was confirmed that pre-deposition annealing of the sputtered ZnO layer at 300°C in air greatly decreased the interfacial trap density (∼2×1012 cm−2 eV−1). X-ray photoelectron spectroscopy showed a decrease in the OH bonds adsorbed on the ZnO surface after pre-deposition annealing, which improved the interface property. A very small capacitance equivalent thickness of 1.3nm was achieved, which decreased the operation voltage (<5V) of the device significantly. [Copyright &y& Elsevier]

Abstract: The improved structural and electrical properties of tin-oxide films produced by using ultralow-pressure sputtering (ULPS) method are reported. The Hall mobility of the film (~13 cm2/V s) deposited using ULPS was about 1.5 times higher than that of the film (~8 cm2/V s) sputtered using a pressure of 4.0×10−1 Pa. As the sputtering pressure was decreased, the film was transformed from an amorphous structure to a nano-crystalline one and gained a stoichiometric SnO2 composition. These changes in the film structure sufficiently decreased the carrier concentration to facilitate application to thin film transistors. [Copyright &y& Elsevier]

Abstract: A thin (∼ 0.5 nm) layer of Hf metal was deposited on an atomic layer deposited (ALD) HfO2 film by the DC sputtering method. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analyses showed that the Hf metal layer transformed into HfO2 during the post-deposition annealing process. It appears that the HfO2 layer formed by the oxidation of Hf metal provided the underlying ALD HfO2 layer with the nucleation sites necessary to decrease the grain-boundary density of the crystallized HfO2 film. The decrease in the grain-boundary density resulted in a reduction in the Hf-silicate formation and interfacial layer growth during post deposition annealing. This eventually resulted in a smaller increase in the capacitance equivalent thickness (CET) and high-k characteristics in the CET vs. leakage current density curve even after post deposition annealing at 1000 °C. [Copyright &y& Elsevier]

Abstract: High-quality GaN epitaxial films were successfully grown directly on 4H-SiC substrates. The difficulty in the nucleation as well as the overgrowth of GaN islands, which is often observed during metal-organic chemical vapor deposition, was solved using the concept of an epitaxial lateral overgrowth technique. The continuous mirror-flat GaN epitaxial film could be obtained at a reduced reactor pressure (76Torr) and a lower N/Ga supply ratio. The full-width half-maximums (FWHMs) of the (0002) and (10 3) rocking curves of the GaN epitaxial films on the 4H-SiC substrate at the optimized condition were 105 and 118arcsec, respectively, under a skew symmetric diffraction geometry. The intense bound exciton lines with a FWHM of 10meV and a free exciton peak appeared in the low-temperature photoluminescence spectrum, illustrating the very high quality of the GaN film on 4H-SiC. [Copyright &y& Elsevier]

To fabricate lateral-field excitation (LFE)-mode solid mounted resonator (SMR)-type film bulk acoustic resonators (FBARs), piezoelectric ZnO layers were deposited in an RF magnetron sputtering system. Control of the crystallinity, microstructure and electric properties of the piezoelectric layers was essential for fabricating high-quality LFE-mode SMR-type FBARs. In the appropriate deposition condition for FBAR devices, ZnO thin films with highly c-axis-preferred orientation (XRD rocking curve, σ=2.17°), high resistivity of 106 Ω cm and surface roughness of 10.6 A˚ were deposited. Optimal substrate rotation was especially important for improvement of the c-axis-preferred orientation of ZnO films. Plasma properties such as the electron temperature, plasma density and saturated ion current were also analyzed for optimal ZnO deposition conditions using a Langmuir double-probe system. The resonator, for which the active piezoelectric area was 200×200 μm2, consisted of 1.25-μm-thick ZnO film and a 110-nm Au electrode. Its series and parallel resonance frequencies appeared at 1.68 and 1.71 GHz, respectively, and the quality factor was 201.4±7.4. [Copyright &y& Elsevier]

Abstract: In this work, we have prepared metal–insulator–metal capacitors for dynamic random access memory capacitor application using atomic layer deposition of TiO2 high-κ dielectric and RuO2 bottom electrode. We compare TiO2 layers grown using TiCl4 precursor or Ti-tetra-isopropoxide precursor, and Al-doped TiO2 layers grown using Ti-tetra-isopropoxide precursor. The capacitors were analyzed in the terms of capacitance – voltage and current – voltage measurements and transmission electron microscopy imaging. [Copyright &y& Elsevier]

• BeO 6 octahedra, a highly metastable local structure, are stabilized by ALD. • An isostructural matrix demonstrates stabilization of highly metastable BeO 6 octahedra. • Be x Mg 1-x O films exhibit almost doubled k with the presence of BeO 6 octahedra. An atomic structure is widely recognized as the key that determines the physical properties of a material. A critical challenge to engineer the atomic structure is that many useful crystals are metastable under ambient conditions and difficult to realize. Here, it is demonstrated that highly metastable atomic arrangements can be synthesized in the isostructural matrix via atomic layer deposition. Studying highly metastable BeO 6 octahedra in rocksalt MgO as a model system, it is experimentally and theoretically shown that the single-phase Be x Mg 1-x O thin films adopt rocksalt structure over wurtzite for the composition range x < 0.21. The single-phase rocksalt films exhibit almost doubled dielectric constants with the presence of BeO 6 octahedra. Such atomic environment engineering may create intriguing properties that have not been realized in the constituent materials. This work provides excellent opportunities to explore unprecedented materials properties via engineering metastable atomic arrangements using the isostructural matrix approach. [ABSTRACT FROM AUTHOR]

• A new capacitive-type FET (CFET) gas sensor based on Si FET is proposed. • Only five photomasks are used to prepare the CFET sensor and a ZnO thin film prepared by atomic layer deposition (ALD) is adopted as a sensing material. • The NO 2 gas-sensing characteristics are obtained by using pulse pre-bias method. • Depending on the polarity of pre-bias (V pre), the CFET gas sensor exhibits the opposite I D behaviors. • The sensing mechanism is explained by using schematic energy band diagrams. A new capacitive-type FET (CFET) gas sensor is proposed in this work and fabricated by using Si FET technology. Only five photomasks are used to prepare the CFET sensor and a ZnO thin film prepared by atomic layer deposition (ALD) is adopted as a sensing material. A diluted nitrogen dioxide (NO 2) is used as a test gas and the sensing properties of the CFET gas sensor are measured at 180℃ by using pulse pre-bias method. It is verified that the response of the CFET sensor is significantly improved as the absolute value of the difference between pre-bias (V pre) and gate read bias (V rCG) increases. However, the response is negligible when V pre = V rCG. The drain current (I D) of the CFET gas sensor increases by 44.6% at a V pre of −2 V while the I D decreases by 43.2% at a V pre of 2 V under exposure to 0.5 ppm NO 2 at a V rCG of 0 V at 180℃. The response and the recovery times are also investigated. The sensing mechanism is explained by using schematic energy band diagrams. [ABSTRACT FROM AUTHOR]

The catalyst-free growth of the GaAs nanowire is based on preferential one-dimensional growth along the <111>B direction of the zinc-blende-structure GaAs, which originates from the formation of facets depending on the temperature and pressure. However, the driving force for preferential growth has yet to be fully elucidated. In this study, the adsorption-desorption behavior for several low-index surfaces was investigated in terms of temperature, pressure, and surface reconstruction using ab-initio thermodynamics. It was found that the As adsorption on the (111)B surface is highly favorable compared to that on the other surfaces under the experimental conditions, where the growth of the GaAs nanowires was successful without catalyst. Based on the thorough calculations and a comparison of the results with those of previous experiments, the driving force behind the preferential one-dimensional growth along the <111>B direction is confirmed to be the preferential adsorption of As on the (111)B surface under the specific temperature and pressure condition. In particular, the Ga-vacancy α(2×2) reconstruction of the (111)B surface, which was calculated to be stable at high temperature, is identified to provide the preferential adsorption sites for the incoming vapor sources. Unlabelled Image • Stable reconstruction of GaAs (111)B changes depending on temperature and pressure. • Ga adsorption on (111)B is favorable under all temperature and pressure considered. • As adsorption on (111)B is favorable under specific temperature and pressure. • Preference of As adsorption on (111)B is not much affected by pre-adsorbed Ga. • As adsorption on (111)B is the limiting factor of GaAs <111>B nanowire growth. [ABSTRACT FROM AUTHOR]