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We demonstrate the rapid (<100 ns) activation and enhancement of solution-processed InZnO thin-film transistors (TFT) via a photo-assisted process: excimer laser annealing (ELA). A single shot is sufficient to enhance mobility from 0.19 cm2 V−1 s−1 to 3.91 cm2 V−1 s−1. Through multiphysics simulation, we confirmed that the process is instantaneous (<100 ns) and induces low substrate temperature suitable for flexible substrates. Analysis of optical properties, elemental concentration, and bonding changes after ELA revealed an improved metal-oxide formation and effective reduction of precursor-related impurities and oxygen vacancy traps. These demonstrate ELA’s potential for high-throughput fabrication of solution-processed devices for large-area, transparent, and flexible electronics. [ABSTRACT FROM AUTHOR]

Laser-assisted doping combined with annealing technique is used in selective areas to form a p–n junction on a SiC thin film grown by the pulsed laser deposition on a Si substrate at a temperature of 800 °C. This approach in an aluminum chloride solution and a phosphoric solution has resulted in p-SiC/n-Si and n-SiC/p-Si hetero-structures, respectively. Further, a functional in-plane p–n junction is realized side-by-side on the post-deposited SiC thin film. I–V characteristics by two probe technique showed the p–n diode characteristics. Blue light (400 nm) electroluminescence from the p–n junction on SiC thin film was observed in the forward biased condition. Further, an improvement in the I–V reverse characteristics was observed by illuminating the p–n SiC thin film with green/blue light. [ABSTRACT FROM AUTHOR]

The effect of laser doping on the contact resistance of ohmic contact to 4H-SiC has been investigated. Laser doping was performed by irradiating a pulse-width stretched KrF excimer laser to an Al film coated on the surface of 4H-SiC. Doping and contact formation on the C-face were investigated. The doping was carried out while keeping the sample at room temperature. The experimental results suggest that the contact made of Ti/Al can achieve specific contact resistance as low as 4.0 × 10−6 Ωcm2 without additional heat treatment. The contact resistance is lower than that reported for ohmic contacts formed using ion implantation. [ABSTRACT FROM AUTHOR]

A thin-film thermoelectric generator composed of p- and n-type poly-Ge1−xSnx (x ∼ 0.02) on a Si(001) covered with SiO2 has been successfully fabricated by low thermal budget processes (under 300 °C) and demonstrated for the first time. Both the crystallization and dopant activation were simultaneously performed using pulsed UV laser irradiation in flowing water. A recorded activation ratio of Sb in the poly-Ge1−xSnx enabled a relatively high power factor (9.2 μ Wcm−1 K−2 at RT), which is comparable to the counterparts of n-type Ge1−xSnx layers epitaxially grown on InP(001). [ABSTRACT FROM AUTHOR]

We propose a simple and easy electrode formation technique on nanopolycrystalline diamond (NPD) synthesized by a high-temperature and high-pressure technique. The stronger light absorption nature of NPD than of standard transparent diamond enables the laser irradiation process on NPD. Pulsed laser irradiation using an ArF excimer laser under atmospheric condition drastically reduced the resistance of the NPD surface by forming graphite. Repetition of the laser irradiation reduced the resistance, showing a resistance of 300 Ω for the laser-irradiated area of 100 × 150 µm2. These results indicate the applicability of pulsed laser irradiation to an NPD apparatus having a conductive electrode, as well as electronic device processes. [ABSTRACT FROM AUTHOR]

A low-temperature process for the formation of heavily doped polycrystalline Ge (poly-Ge) layers on insulators is required to realize next-generation electronic devices. In this study, we have systematically investigated pulsed laser annealing (PLA) in flowing water for heavily doped amorphous Ge1−xSnx layers (x ≈ 0.02) with various dopants such as B, Al, Ga, In, P, As, and Sb on SiO2. It is found that the dopant density after PLA with a high laser energy is reduced when the oxidized dopant has a lower oxygen chemical potential than H2O. As a result, for the p-type doping of B, Al, Ga, and In, we obtained a high Hall hole density of 5 × 1019 cm−3 for PLA with a low energy. Consequently, the Hall hole mobility is limited to as low as 10 cm2 V−1 s−1. In contrast, for As and Sb doping, because the density of substitutional dopants does not decrease even after PLA with a high energy, we achieved a high Hall electron density of 6 × 1019 cm−3 and a high Hall electron mobility simultaneously. These results indicate that preventing the oxidation of dopant atoms by water is an important factor for achieving heavy doping using PLA in water. [ABSTRACT FROM AUTHOR]

This paper focuses on the bonding interface of LiNbO3 and Si wafers bonded by laser irradiation. The nanostructure and composite distribution across the bonding interface were investigated. The experimental interface analysis showed that no cracks or voids were formed at the nanolevel. It was also found that the bonding interface had a disordered amorphous layer containing Nb, O, and Si. This indicates that a strong bond was achieved because fusion bonding proceeded at the interface between LiNbO3 and Si. In addition, the effectiveness of this bonding method for the wafer-level bonding of LiNbO3 and Si was demonstrated. [ABSTRACT FROM AUTHOR]

The formation of perhydropolysilazane (PHPS)-based SiO2 films by CO2 laser annealing is proposed. Irradiation with a CO2 laser with optimum fluence transformed a prebaked PHPS film into a SiO2 film with uniform composition in the thickness direction. Polycrystalline silicon thin-film transistors (poly-Si TFTs) with a SiO2 film as the gate insulator were fabricated. When the SiO2 film was formed by CO2 laser annealing (CO2LA) at the optimum fluence of 20 mJ/cm2, the film had fewer OH groups which was one-twentieth that of the furnace annealed PHPS film and one-hundredth that of the SiO2 film deposited by plasma-enhanced chemical vapor deposition (PECVD) using tetraethyl orthosilicate (TEOS). The resulting TFTs using PHPS showed a clear transistor operation with a field-effect mobility of 37.9 ± 1.2 cm2 V−1 s−1, a threshold voltage of 9.8 ± 0.2 V, and a subthreshold swing of 0.76 ± 0.02 V/decade. The characteristics of such TFTs were as good as those of a poly-Si TFT with a SiO2 gate insulator prepared by PECVD using TEOS. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a bonding method in ambient air using laser irradiation to the face-to-face interface of dissimilar materials. This method is performed while keeping whole wafers of the materials at room temperature. We demonstrate the bonding of LiNbO3 to Si using pulsed nanosecond green laser irradiation. Laser use can minimize thermal stress owing to a large thermal expansion mismatch. The bonding characteristic obtained by an irradiation laser up to 2.5 J/cm2 in fluence is investigated. It is found that a LiNbO3 chip is strongly bonded to a Si chip by setting the laser fluence at the optimum range. A bond strength of over 2 MPa, which may be enough for the device applications, can be obtained. [ABSTRACT FROM AUTHOR]

Aluminum (Al) is doped into 4H-SiC by excimer laser irradiation to a coated Al film on the 4H-SiC surface. Deep (∼200 nm in the depth) and high-concentration (over 1 × 1021/cm3 on the surface) Al doping is realized by adjusting the Al film thickness for the laser fluence. Optical emission measurements clearly show that Al plasma is generated on and above the sample surface by laser irradiation. Surface morphology observation suggests that, under an optimum combination between Al thickness and laser fluence, high-temperature molten Al is formed on the 4H-SiC surface and the molten Al serves as the dopant source. We adopt this laser Al doping to fabricate a junction barrier Schottky (JBS) diode. Selective doping is performed by using SiO2 as the doping mask. The fabrication is thoroughly carried out without heating the substrate except for film deposition and metal sintering processes. The fabricated JBS diode shows satisfactory operation as compared with a pn junction diode. [ABSTRACT FROM AUTHOR]

We demonstrate the use of excimer laser annealing (ELA) as a low temperature annealing alternative to anneal amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) passivated by a solution-processed hybrid passivation layer. Usually, a-IGZO is annealed using thermal annealing at high temperatures of up to 400 °C. As an alternative to high temperature thermal annealing, two types of ELA, XeCl (308 nm) and KrF (248 nm) ELA, are introduced. Both ELA types enhanced the electrical characteristics of a-IGZO TFTs leading to a mobility improvement of ~13 cm2 V−1 s−1 and small threshold voltage which varied from ~0–3 V. Furthermore, two-dimensional heat simulation using COMSOL Multiphysics was used to identify possible degradation sites, analyse laser heat localization, and confirm that the substrate temperature is below 50 °C. The two-dimensional heat simulation showed that the substrate temperature remained at very low temperatures, less than 30 °C, during ELA. This implies that any flexible material can be used as the substrate. These results demonstrate the large potential of ELA as a low temperature annealing alternative for already-passivated a-IGZO TFTs. [ABSTRACT FROM AUTHOR]

We report nitrogen (N) doping of 4H-SiC by KrF excimer laser irradiation in liquid N2. In comparison to phosphorus (P) doping performed using phosphoric acid solution, the laser N doping can introduce N atoms deeper (∼1 µm depth) into the 4H-SiC, which results in reduction of doped layer resistance by approximately 3 orders of magnitude. Doping is shown to proceed by the thermal diffusion of species, while loss of the host material from the surface by ablation takes place at the same time. Chemical analysis shows that high density carbon (C) vacancies are generated in the N doped region, which suggests enhanced diffusion of N assisted by the presence of C vacancies. pn junction diodes are formed by using the N doping technique. Turn-on voltage is ∼−3 V, which is reasonable for a pn junction diode of 4H-SiC. [ABSTRACT FROM AUTHOR]