High-quality Epitaxial Layers Research Articles

High-performance GaN ultraviolet polarization-sensitive photodetector based on ferroelectric polarization LiNbO3

High responsivity ultraviolet (UV) photodetectors (PDs) are essential for abundant civilian and military applications. Gallium nitride (GaN) has emerged as an ideal material for UV PD fabrication due to its favorable properties. However, the quality of GaN epitaxial layers significantly impacts device performance and reliability. Sapphire-based GaN epitaxial growth technology enables the realization of high-quality GaN epitaxial layers, making it the preferred choice for GaN substrates. Nonetheless, the thermal expansion coefficient mismatch between sapphire and GaN can lead to crystal mismatch and stress accumulation at high temperatures, affecting device performance and reliability. In contrast, lithium niobate (LiNbO3) exhibits similar coefficients of thermal expansion to GaN, mitigating crystal mismatch and stress accumulation issues. Here, we report the realization of a GaN UV PD by laminating GaN membrane onto ferroelectric LiNbO3 through selective electrochemical etching of the sapphire-based GaN epitaxial film. The LiNbO3-based GaN PD achieves a specific high on/off ratio of 107. At a 5 V bias voltage, the device exhibits a high peak responsivity of 1.712 × 103 A/W under 325 nm laser illumination. Furthermore, the device demonstrates excellent performance for polarization light detection, with a polarization ratio of approximately 54.95. Exploiting the local ferroelectric polarization of x-cut LiNbO3, the photogenerated electron–hole pairs in GaN are efficiently separated by the electrostatic field from the polarization of ferroelectric LiNbO3, resulting in enhanced light-to-electric conversion efficiency. Our work presents a method for fabricating high responsivity GaN-based UV PD, showcasing the potential of integrating ferroelectric LiNbO3 to enhance device performance.

Optimizing the chemical vapor deposition process of 4H–SiC epitaxial layer growth with machine-learning-assisted multiphysics simulations

This work addresses a novel technique for selecting the best process parameters for the 4H–SiC epitaxial layer in a horizontal hot-wall chemical vapor reactor using a transient multi-physical (thermal-fluid-chemical) simulation model and combined with a machine-learning model. An experiment was performed to validate the feasibility of the numerical model. Secondly, a single-factor analysis was conducted to investigate the effects of process parameters, including the deposition temperature, inlet-flow volume, rotational speed of the susceptor, and cavity pressure, on the quality of the 4H–SiC epitaxial layer. Finally, a machine learning algorithm, the ant colony optimization-back propagation neural network (ACO–BPNN), was employed to develop the input/output model and optimize process parameters for obtaining a high-quality epitaxial layer and reducing the optimization cycle and costs. Notably, the optimized process was validated by real experiments, where the error between calculation and experiment is 4.03 % for deposition rate and 0.49 % for coefficient of variation, respectively. The results highlight the model as reliable and lay the foundation for the CVD growth of the 4H–SiC epitaxial layer.

Fabrication of low thermal resistance 3C-SiC/diamond structure for GaN epitaxial layer growth

Integrating diamonds with GaN presents a promising solution for enhancing heat dissipation. However, a critical challenge lies in developing an engineering substrate that facilitates the growth of high-quality GaN epitaxial layers, enabling the production of GaN-based devices with superior thermal management on a large scale. In this study, we have successfully developed an engineering substrate conducive to high-quality GaN growth. This accomplishment was achieved through the direct transfer of a 3 C-SiC thin film, originally grown on Si, to a diamond substrate at room temperature using the surface-activated bonding technique. After the transfer process, we observed the presence of a SiC amorphous layer at the interface, measuring approximately 18.5 nm in thickness. Notably, this thickness reduced to 14.5 nm after annealing at 1100 °C, indicating a transformation from amorphous to polycrystalline SiC due to recrystallization. Furthermore, it is crucial to highlight that no exfoliation of the 3 C-SiC/diamond bonding interfaces was observed even after subjecting them to annealing at 1100 °C. This observation is pivotal for ensuring the high-quality growth of GaN crystals on diamonds. The thermal boundary conductance of the 3 C-SiC/diamond interface reached nearly 93 MW/m2·K, demonstrating significant efficiency for device cooling. These compelling results highlight the potential of the 3 C-SiC/diamond engineering substrate to enable high-performance GaN-based devices, providing significantly enhanced thermal management capabilities. This breakthrough represents a major stride forward in the field.

Selective Growth of GaP Crystals on CMOS-Compatible Si Nanotip Wafers by Gas Source Molecular Beam Epitaxy.

Gallium phosphide (GaP) is a III-V semiconductor with remarkable optoelectronic properties, and it has almost the same lattice constant as silicon (Si). However, to date, the monolithic and large-scale integration of GaP devices with silicon remains challenging. In this study, we present a nanoheteroepitaxy approach using gas-source molecular-beam epitaxy for selective growth of GaP islands on Si nanotips, which were fabricated using complementary metal-oxide semiconductor (CMOS) technology on a 200 mm n-type Si(001) wafer. Our results show that GaP islands with sizes on the order of hundreds of nanometers can be successfully grown on CMOS-compatible wafers. These islands exhibit a zinc-blende phase and possess optoelectronic properties similar to those of a high-quality epitaxial GaP layer. This result marks a notable advancement in the seamless integration of GaP-based devices with high scalability into Si nanotechnology and integrated optoelectronics.

(Ga,Mn)N—Epitaxial growth, structural, and magnetic characterization—Tutorial

The spin control possibility and its application in optoelectronic devices began an intensive research into its utilization, in particular, in the wide-gap semiconductors such as GaN doped with transition metal ions. Due to a strong p–d hybridization in Ga1−xMnxN, the Curie temperature above 300 K was already expected for x = 5%, providing that the free hole concentration necessary for the hole-mediated ferromagnetism exceeds 1020 cm−3. In this context, the development of non-equilibrium techniques enabled the engineering high-quality epitaxial layers of (Ga,Mn)N exhibiting uniform ferromagnetism at low-end cryogenic temperatures. The Tutorial is focused on the molecular beam epitaxy growth method of the Mn-enriched GaN magnetic semiconductors, summarizes the (Ga,Mn)N structural and electronic studies, and explains fundamental ferromagnetic properties, including the determination of the Mn concentration and the Curie temperature based on magnetic measurements. Most studies reveal the homogenous substitution of Mn3+ ions in the GaN matrix. Nevertheless, achieving room-temperature ferromagnetism still remains a challenge. Therefore, in the Tutorial, future research is suggested that can help obtain the homogenous ferromagnetism in (Ga,Mn)N at much elevated temperatures.

Defects in layered boron nitride grown by Metal Organic Vapor Phase Epitaxy: luminescence and positron annihilation studies

Defects in two-dimensional boron nitride (BN) are candidates for a manifold of applications, for example, as single-photon emitters or optically addressable spin defects. However, the topic has proven to be complex and despite extensive research efforts, knowledge on midgap defects and their signature in photoluminescence (PL) remains fragmentary. Mass production of high-quality layered BN by Metal Organic Vapor Phase Epitaxy (MOVPE) is possible and effective, thus understanding the conditions of formation and identifying defects that arise in the material grown by this method is extremely important. Here, we present an analysis of the influence of the MOVPE growth conditions of layered BN on the occurrence of specific structural defects. PL spectra in the visible range were analysed involving the Huang-Rhys theory implemented in the fitting procedure for polycrystalline samples grown under various conditions. Such an approach allowed us to separate bands from individual entities. Two bands at 1.57 eV and 2.6 eV with phonon replicas were observed. The three additional bands are characterized by a broad emission centered at 1.38 eV, 1.9 eV and 2.24 eV. Further properties, including an analysis of the surface morphology, the impact of annealing and laser bleaching on the PL spectra and Positron Annihilation Spectroscopy (PAS) were considered to draw conclusions about the nature of the examined defects. The PAS analysis correlated with the PL of the BN layers allows us to classify the studied samples in terms of the concentrations of boron vacancies and their complexes. Based on the obtained results, we propose that the rich family of PL bands observed in various sp2-BN layers is associated with different defect complexes build of boron vacancies (VB), boron antisite defects (BN), substitutional carbon defects (CB, CN) and their donor-acceptor pairs. The main value of this paper is the transfer of knowledge gained about defects and the corresponding luminescent bands to characterize high-quality continuous epitaxial sp2-BN layers. The presented results constitute an important step toward the deterministic manipulation of defect concentrations in two-dimensional boron nitride, which opens up new pathways for future optoelectronic device application.

High-quality heteroepitaxy of ε-Ga2O3 films on 4H-SiC substrates grown via MOCVD

High-quality ε-Ga2O3 epitaxial layers were grown on a 4H-SiC substrate via MOCVD. A (004) XRC FWHM of the ε-Ga2O3 epitaxial layer as small as 0.09° (341 arcsec) is achieved.

SrTiO3 Epitaxially Protected Si-Photocathode for Photoelectrochemical Water Splitting

Although silicon has been demonstrated to be one of the best photoelectrochemical (PEC) substrate materials thanks to its low cost, mature manufacturing technique, and high theoretical photovoltage and saturation current density [1], the development of robust Si-based PEC device has remained an existing challenge due to the fact that it is very easily susceptible to (photo)corrosion under PEC operational conditions [2]. Therefore, a suitable protective layer over the Si substrate which is able to simultaneously provide the corrosion resistance and retain a highly efficient charge transfer across the photoelectrode device is highly desired [3].To this end, we prepared high-quality SrTiO3 (STO) layer to passivate p-Si substrate via the mediation of an epitaxial enabler reduced graphene oxide (rGO) using the pulsed laser deposition (PLD) technique. STO layers with different thicknesses were prepared on both rGO-buffered and bare Si substrates to investigate the effects of epitaxy and charge carrier migration distance on the PEC performance. It was realized that very thin (3.9 nm ~ 10 unit cells) STO layer epitaxially overgrown on rGO-buffered Si showed the highest onset potential (0.326 V vs RHE, defined as potential at -0.1 mA cm-2) than the counterparts with thicker and/or non-epitaxial STO. The photovoltage and flat-band potential analyses, and the electrochemical impedance spectroscopy measurements showed that the epitaxial protected photocathode was more beneficial for charge separation, charge transfer, and the targeted redox reaction (hydrogen evolution reaction in this case) than the non-epitaxial one. The STO/rGO/Si with a smooth and highly epitaxial STO layer outperforming the direct contacted STO/Si with textured and polycrystalline STO layer underscored the importance of having well-defined passivation layer. In addition to that, numerous pinholes formed in STO/Si attributable to highly energetic bombardment process in the PLD deposition led to a rapid degradation of photocathode during PEC measurements, possibly because the electrolyte could easily penetrate into the film and consequently corrode the substrate. Single-oriented STO realized by rGO-buffered substrate potentially rendered easier path for charge migration, and the thinnest STO layer provided the shortest transportation route while maintained the robust protection ability. Polycrystalline STO in direct contacted STO/Si however presented more recombination sites which eventually impaired the PEC performance. Smooth surface of high-quality epitaxial STO layer with sub-nano roughness demonstrated to be a pivotal factor in remotely protecting underlying p-Si substrate from corrosion, while the presence of pinholes in non-epitaxial sample showed a similar degradation rate as bare Si substrate which was without any protection. We also studied the capability of STO layer in protecting underlying Si substrate from corrosion, and the long-term stability tests demonstrated the robustness of epitaxial STO layer-coated photocathode in comparison to bare Si.We demonstrated that STO layer overgrown on Si buffered with few-layer epitaxy enabler rGO could promote charge carrier transfer across the photocathode and lead to better PEC performance. Through a series of in-situ and ex-situ characterizations we verified that the addition of rGO layer could significantly alter the STO layer crystallinity and thin film morphology and, most importantly, enhance the stability of Si photocathode with only 10 unit cells layer. This study reported a facile approach for preparing a robust protection layer over photoelectrode substrate in realizing efficient and at the same time durable PEC device. Acknowledgement: This study was supported by Slovenian Research Agency (Project No. N2-0187) and the Czech Science Foundation (Project No. 21-20110K). We also thank the supports from Mr. Damjan Vengust in electron microscope observations, Mr. Jožko Fišer in Pt thin film preparation, Dr. Vasko Jovanovski in discussion of electrochemical measurements.

H-Terminated Diamond MOSFETs on High-Quality Diamond Film Grown by MPCVD

Diamond-based transistors have been considered as one of the best choices due to the numerous advantages of diamond. However, difficulty in the growth and fabrication of diamond needs to be addressed. In this paper, high quality diamond film with an atomically flat surface was grown by microwave plasma chemical vapor deposition. High growth rate, as much as 7 μm/h, has been acquired without nitrogen doping, and the root mean square (RMS) of the surface roughness was reduced from 0.92 nm to 0.18 nm by using a pre-etched process. H-terminated diamond MOSFETs were fabricated on a high-quality epitaxial diamond layer, of which the saturated current density was enhanced. The hysteresis of the transfer curve and the shift of the threshold voltage were significantly reduced as well.

Characterization of (001) β-Ga2O3 Schottky diodes with drift layer grown by MOCVD

Growing a thick high-quality epitaxial layer on the β-Ga2O3 substrate is crucial in commercializing β-Ga2O3 devices. Metal organic chemical vapor deposition (MOCVD) is also well-established for the large-scale commercial growth of β-Ga2O3 and related heterostructures. This paper presents a systematic study of the Schottky barrier diodes fabricated on two different Si-doped homoepitaxial β-Ga2O3 thin films grown on Sn-doped (001) and (010) β-Ga2O3 substrates by MOCVD. X-ray diffraction analysis of the MOCVD-grown sample, room temperature current density–voltage data for different Schottky diodes, and C–V measurements are presented. Diode characteristics, such as ideality factor, barrier height, specific on-resistance, and breakdown voltage, are studied. Temperature dependence (170–360 K) of the ideality factor, barrier height, and Poole–Frenkel reverse leakage mechanism are also analyzed from the J–V–T characteristics of the fabricated Schottky diodes.

High quality AlN film assisted by graphene/sputtered AlN buffer layer for deep-ultraviolet-LED

The advantages of van der Waals epitaxial nitrides have become a research hot topic. It is worth noting that graphene plays an important role in the research of epitaxial AlN epitaxial layer. In this work, we demonstrate a method to obtain high-quality and low-dislocation AlN epitaxial layer by combining graphene and sputtered AlN as the nucleation layer on the C-sapphire substrate via metal organic chemical vapor deposition, and successfully fabricated a 277 nm AlGaN-based deep ultraviolet light emitting diode (DUV-LED) based on the obtained AlN epitaxial layer. The presence of graphene promotes the stress release of AlN. Compared with the AlN epitaxial layer directly grown on graphene/sapphire substrate, the exist of sputtered AlN/graphene nucleation layer facilitates most of the threading dislocations in AlN can annihilate each other in the range of about 100 nm. Thus, as grown AlN epitaxial layer shows the decreasing of the screw dislocation from 2.31 × 109 to 2.08 × 108 cm−2 significantly. We manufacture an DUV-LED with 277 nm emission wavelength by using high-quality AlN films, which shows that magnitude of the leakage current is only on the order of nanoamperes and the forward turn on voltage is 3.5 V at room temperature. This study provides a meaningful strategy to achieve high-quality AlN film and high-performance DUV-LED.

High-quality AlN epilayers prepared by atomic layer deposition and large-area rapid electron beam annealing

Low-temperature atomic layer deposition and high-temperature electron beam annealing (EBA) are used to achieve high-quality epitaxial AlN layers. Efficient energy transfer from the single exposure for only 1 min of electron irradiation with a large area contributes to substantial improvement in the film density and crystal quality of AlN thin films, as demonstrated by the X-ray reflectivity and the θ-2θ/ω-scan X-ray diffraction. High-resolution transmission electron microscopy indicates well-arranged lattice fringes in the epitaxial AlN layer on a sapphire substrate. A low surface roughness of the AlN epilayer, as revealed by the atomic force microscopy, suggests that the damage induced by the EBA treatment is insignificant. The outcomes indicate that the large-area rapid EBA is a low-damage and efficient technique for the recrystallization of thin films prepared at low temperatures.

High Operating Temperature Mid-Infrared InGaAs/GaAs Submonolayer Quantum Dot Quantum Cascade Detectors on Silicon

Monolithic integration of infrared photodetectors on a silicon platform is a promising solution for the development of scalable and affordable photodetectors and infrared focal plane arrays. We report on integration of submonolayer quantum dot quantum cascade detectors (SML QD QCDs) on Si substrates via direct growth. Threading dislocation density has been reduced to the level of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{7}$ </tex-math></inline-formula> cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-2}$ </tex-math></inline-formula> with the high-quality GaAs-on-Si virtual substrate. We also conducted a morphology analysis for the SML QD QCDs through a transmission electron microscope strain contrast image and to the best of our knowledge, high quality InGaAs/GaAs SML QDs were clearly observed on silicon for the first time. Photoluminescence decay time of the as-grown SML QD QCDs on Si was measured to be around 300 ps, which is comparable to the reference QCDs on lattice-matched GaAs substrates. With the high-quality III-V epitaxial layers and SML QDs, the quantum cascade detectors on Si achieved a normal incident photoresponse temperature up to 160 K under zero bias.

Characterization of epitaxial layers grown on 4H-SiC (0 0 0 −1) substrates

SiC is an excellent semiconductor material that can be used in power semiconductor devices. It has the advantages of high thermal conductivity, stable chemical properties, and high critical breakdown field strength. The active region of a SiC device is usually in the SiC epitaxial layer, so the growth of high-quality SiC epitaxial layers is extremely valuable. In this paper, we investigate the epitaxial growth of SiC on n-type 4° off-axis SiC (0 0 0–1) substrates. We used a horizontal hot-wall chemical vapor deposition apparatus for rapid epitaxy on SiC substrates, using C2H4, and SiHCl3 as precursors and H2 as carrier gas, respectively, and growing at 1350 °C,1400 °C,1450 °C,1500 °C, 1550 °C, 1600 °C for half an hour to get epitaxial layer. The effect of growth temperature on the surface morphology of SiC (0 0 0 –1) epitaxial layer was analyzed and epitaxial layers is characterized by optical microscope, scanning electron microscope, atomic force microscope and Raman scattering instrument, and the growth rate of epitaxial layer was obtained. It is found that the higher growth temperature is helpful to obtain the epitaxial layer with smooth surface and higher content of 4H-SiC under certain pressure, C/Si molar ratio, and following rate of precursor and carrier gas.

Numerical Modelling for the Experimental Improvement of Growth Uniformity in a Halide Vapor Phase Epitaxy Reactor for Manufacturing β-Ga2O3 Layers

The development of growth processes for the synthesis of high-quality epitaxial layers is one of the requirements for utilizing the ultrawide band gap semiconductor Ga2O3 for high-voltage, high-power electronics. A halide vapor phase epitaxy (HVPE) process used to grow β-Ga2O3 layer was optimized by modifying the gas inlet, resulting in improved growth uniformity. A conventional tube acting as an inlet for the Ga precursor GaCl gas was replaced with a shower head with four outlets at 45 degrees to the horizontal axis of the reactor. The modification was performed based on numerical calculations of the three-dimensional distribution of gases inside the growth chamber with different designs of the GaCl precursor inlet. It was shown that variation in the Ga/O ratio over the substrate holder was ~10% for a shower head compared with ~40% for a tube. In addition, growth with a tube leads to the film thickness varying by a factor of ~4 depending on the position on the holder, whereas when using a shower head, the thickness of the grown Ga2O3 layers became much more uniform with a total spread of just ~30% over the entire substrate holder.

From a single silicon carbide detector to pixelated structure for radiation imaging camera

Abstract In this work, Schottky detectors based on a high-quality 4H-SiC epitaxial layer with a thickness of 50 µm were prepared. The Schottky contact of Ni/Au metallization with a 3 mm diameter was made. Reverse current-voltage characteristics were measured up to a voltage of 300 V with a leakage current of 40 pA at room temperature. Using an α-particle radiation source, the spectrometric characteristics of the 4H-SiC detector were tested. The best energy resolution in the FWHM (Full Width and Half Maximum) about 15 keV for 5.5 MeV α-particles was observed. Furthermore, a 4H-SiC pixel sensor (256 × 256) for the Timepix3 reading chip was prepared. The spectrometric and imaging properties of the new Timepix3 detector based on the 4H-SiC sensor were tested. The results showed high energy resolution and also high-quality X-ray imaging of the biological object.

Atomically Smooth Defect-Free III-As Heterostructures on InP(111) Substrate for Next-Generation Electronic Devices

Research into Zinc Blende III–V compound semiconductors has focused almost entirely on growth on (001)-oriented substrates for more than five decades. This is because high-quality epitaxial layers can be achieved relatively smoothly when III–Vs are grown on (001) substrates. However, emerging technologies generated renewed interest in the growth of high-quality III–Vs on (111)-oriented substrates. Prime examples of these applications are devices based on spin transport, and low-anisotropy tensile-strained quantum dots for quantum computing applications. Growth on (111) substrates could also help understand the growth of complex chalcogenides. Exploring these applications requires high-quality epitaxial thin films on (111) substrates. Here, we demonstrate for the first time the atomically smooth and defect-free growth of nanoscale InGaAs/InAlAs superlattice on InP(111)-oriented substrate using molecular beam epitaxy (MBE). This was achieved by optimizing the substrate misorientation angle and growth conditions. The growth optimization was guided by scanning transmission electron microscopy Moiré geometrical phase analysis and density functional theory calculations. It is shown that ensuring the step-flow growth mode for each ternary layer is the most effective way of achieving high-quality epitaxial structures on (111)-oriented substrates. This work sets the stage for developing InGaAs/InAlAs/InP(111) electronic and photonic structures with properties that can be tuned with strain-mediated piezoelectric field engineering in high-quality epitaxial thin films. The reported observations should help optimize epitaxy in other Zinc Blende material systems for the structure that could benefit from the tunable piezoelectric effects.

Critical review of Ohmic and Schottky contacts to β-Ga2O3

Over the last decade, beta-phase gallium oxide (β-Ga2O3) has developed an extensive interest for applications such as high-power electronics. Due to its ultrawide bandgap of ∼4.8 eV and predicted breakdown field of ∼8 MV/cm along with its ability to be grown from the melt, this material demonstrates immense promise for high-voltage switching. The pace of development for β-Ga2O3 over these past ten years has been rapid, and ample new information has been generated on metal/β-Ga2O3 interfaces. With the advent of high-quality melt-grown substrates and epitaxial layers, low ideality factors (&amp;lt;1.1) and high Schottky barrier heights (&amp;gt;2.2 eV) have been demonstrated for Schottky contacts. For Ohmic contacts, specific contact resistivities of the common Ti/Au metallization are routinely reported in the 10−5–10−6 Ω cm2 range. This critical and comprehensive review focuses on the fundamental physics of Ohmic and Schottky contacts to bulk and epitaxial β-Ga2O3 in the published literature. It centers on the influence of surface treatments and defects on electrical contacts, Ohmic contacts, and Schottky contacts to β-Ga2O3. Native upward band bending is observed on β-Ga2O3, and the influence of wet and dry etching on band bending along with Schottky barrier height and ideality factor is discussed. Work on Ohmic contacts concentrates on the conventional Ti/Au anneal but additional Ohmic metallizations such as conductive oxides and others are treated as well. Schottky contacts are examined with specific focus on Fermi level pinning, thermal stability of Schottky metallizations, and Schottky barrier inhomogeneity.

GaN growth on ScAlMgO4 substrates via thermally-dewetted thin Al films

In this note, we demonstrate the high-temperature growth of GaN on ScAlMgO4 substrates by metalorganic vapor phase epitaxy when a thin Al film is deposited ex situ on the ScAlMgO4 surface, prior to GaN growth. Mirror-like high-quality GaN epitaxial layers were obtained when N2 was used as carrier gas during the reactor temperature ramp-up preceding GaN growth, leading to a higher GaN quality compared to direct growth on ScAlMgO4 using a trimethylaluminium preflow. This opens a pathway for high-temperature GaN growth on ScAlMgO4 when an Al precursor line is not present.

The straightforward fabrication of thin silicide layers at low temperatures by employing the molecular-incident reaction effect

Because of the ease of formation, and good lattice match with Si, metal silicides often form high-quality epitaxial layers and have established themselves over the years as important technological materials with industrial applications. For the fabrication of silicon-based devices, the contact between metal electrodes and Si is a key issue. The properties of thin films on silicon substrates are strongly dependent on their microstructure and local chemistry. However, a concrete understanding of the influence of a silver layer on different transition metal/silicon interfaces is not currently available. We propose, for the first time, a new model called molecular-incident reaction effect (MoIRE) model that successfully explains the different chemical reactions for Co/Si and Ni/Si interfaces by the introduction of a 3×3R30o-Ag layer. The interaction transfer of silicon atoms forms a Co silicide for Co/3×3R30o-Ag/Si(111) with a thickness of a few nanometers, thus greatly reducing the temperature needed for the formation of a layered CoSi2 silicide compared to that for typical CoSi2 silicide formation at a Co/Si interface. Based on the MoIRE mechanism, the introduction of the 3×3R30o-Ag layer as an intermediate layer permits the silicidation temperature needed to produce a NiSi layer to be reduced to 400 K from typically above 600 K. This approach is advantageous for the formation of a silicide at the Ni/Si interface at low temperature. Based on the MoIRE model for silicide formation at Ni/3×3R30o-Ag/Si(111), we propose a technique for the synthesis Ni silicide layers at lower temperatures with simpler fabrication steps due to the difference in the properties between Co and Ni. This mechanism of low-temperature fabrication includes the formation of (1) a 3×3R30o-Ag and (2) a NiSi layer. The findings presented herein will be useful for more efficiently forming salicides in integrated circuit fabrication, as well as for developing superconducting circuits and quantum bits for quantum computing.