Advanced Electronic Materials最新文献

(Optoelectronic devices are essential for various applications, and their transparent photovoltaic versions offer greater flexibility for self-powered optoelectronics in sensing, system miniaturization, and data-driven learning. This study explores the use of transparent conducting substrates (TCS) to modulate optoelectronic performances through effective carrier concentration, which determines whether heterojunctions are more suitable for photovoltaics or self-powered photosensing applications. The TCS includes doped semiconductors, metal nanowire networks, and oxide/metal/oxide multilayered materials to form transparent heterojunctions, which are carefully designed. The structural, optical, and electrical properties of TCS are investigated to understand their role in designing application-suitable transparent heterojunction devices (THD). TCS plays a crucial role in tuning device electrostatics, enabling improved photovoltaic performance (open circuit voltage of 422 mV, short circuit current density of 2.2 mA cm⁻², fill factor of 48% and power conversion efficiency of 4.39% under 365 nm) with onsite power and photosensing capabilities with fast response times (54 µs). Among the TCS, highly doped metal oxides are particularly significant due to the role of dopants in junction formation, as revealed from impedance spectroscopy. Additionally, metal substrates, including nanowire networks and ultrathin-metal-oxide composites demonstrate self-powered photoresponses through the pyro-phototronic effect, offering stable and enhanced performance. This study demonstrates versatile deployment of oxide heterostructure on a variety of substrates for developing data-driven applications of photocommunication and self-powered sensors, while highly doped oxide can be preferred for onsite power generation applications for sustainable optoelectronics.)

Bilayer MoS₂ exhibits bandgap narrowing under a vertical electric field due to inversion symmetry breaking, with the extent of reduction scaling proportionally with field strength. Leveraging this intrinsic property, this study investigates its impact on the performance of bilayer MoS₂ Schottky barrier field-effect transistors, with a particular focus on the role of Schottky barrier height reduction in improving subthreshold swing. Density functional theory calculations quantify field-dependent shifts in the conduction and valence band edges, which are integrated into transport simulations considering thermionic emission and tunneling at the metal-semiconductor interface, as well as drift-diffusion in the channel. The barrier height reduction achieves a subthreshold swing of 44.7 mV/dec in a bilayer MoS₂ FET with a 2 nm HfO₂ gate dielectric, representing a 37.5% improvement. In a CMOS inverter configuration, barrier height reduction leads to improvements in switching speed by up to 38% and reduces total power consumption by approximately 5%, demonstrating its effectiveness in enhancing both performance and energy efficiency.

IGZO has been identified as a promising channel material for next-generation memory integration. Although extensive studies have been carried out to optimize the electric transport properties, the trade-off between mobility and threshold voltage remains to be challenging. Furthermore, the subthreshold swing often degrades at more positive threshold voltages. Atomic layer deposition (ALD) offers the unique capability to control the layer composition and element arrangement at the atomic level with additional tunability from supercycle growth conditions at different temperatures. This work employs a supercycle thermal ALD method for IGZO deposition and systematically investigates the influence of deposition temperatures and compositions on the electrical characteristics of IGZO FETs. The results reveal that increasing the deposition temperature enhances the surface reactions of metal precursors, reducing carbon residues substantially in the IGZO channel, with the M-O peak proportion reaching 89.8% at 300°C and oxygen-related impurities decreasing to 4.1%. Furthermore, as the In₂O₃ sub-cycle varies from 5 to 1, the ratio of oxygen vacancies decreases from 21.0% to 8.6%, with a widely tunable threshold voltage from −2 to +2.3 V. It should be noted that the mobility with the most positive threshold voltage of 2.3 V still exceeds 15 cm² V⁻¹ s⁻¹. Furthermore, the subthreshold slope of the optimized transistors keeps under 65 mV dec⁻¹ for the entire range of threshold voltages and can reach the ideal value of 60 mV dec⁻¹ for V_th near 0.5 V. This work provides valuable insights into co-optimizing mobility and V_th while keeping low SS by tuning the ALD growth parameters for IGZO.

Hafnium oxide (HfO₂) exhibits multiple polymorphs, each with distinct properties and is a promising material for non-volatile memory technologies in radiation-harsh environments. To gain a comprehensive understanding of the radiation response of HfO₂-based memory devices requires detailed investigations of ion beam-induced phase changes as well as, recrystallization processes and amorphization in the different HfO₂ polymorphs. This study explores the effects of swift heavy-ion irradiation on HfO₂ in resistive random-access memories (RRAM) and metal-insulator-metal (MFM) capacitors, using 1.635 GeV Au ions, to simulate an extreme damage scenario, and 183 MeV Ca ions, which are more relevant to space missions due to their lower mass. The exposure of RRAM layers and MFM capacitors to Ca ions has a negligible effect on the crystallinity of HfO₂ with little to no impact on the switching behavior of the capacitors, indicating that the energy loss threshold for inducing phase transitions is not exceeded. Comparing La-doped HfO₂ (HLO) and hafnium zirconium oxide (HZO) MFM capacitors reveals that HZO exhibits remarkable resilience against Au ion irradiation up to fluences of 7 × 10¹² ions/cm², without any reduction in saturation polarization and that the ferroelectric properties of HLO and HZO can be restored and even enhanced through post-irradiation cycling.

Reconfigurable and programmable metasurfaces require reliable strategies for dynamic control of their electromagnetic response. Among the approaches explored so far, low-temperature plasma is particularly attractive thanks to its tunable permittivity, which can be adjusted in real time via electron density modulation. Despite this potential, quantitative experimental validation at microwave frequencies has remained limited. In this work, we present a comprehensive characterization of plasma tubes as reconfigurable building blocks for metasurface architectures. Using a custom waveguide measurement setup, we retrieve key plasma parameters–such as electron density and plasma frequency–under varying excitation conditions. These measurements are complemented by multiphysics plasma simulations, full-wave electromagnetic modeling, and circuit-level electrical diagnostics, ensuring cross-validation across independent methodologies. Our results demonstrate a continuous and controllable tunability of the plasma response, with electron densities reaching the $��{10}^{19}�m^{�-�3�}�$ range. The close agreement between experiments, models, and simulations confirms the feasibility of integrating plasma elements into adaptive metasurfaces. This study establishes plasma tubes as viable dynamic meta-atoms, paving the way toward high-power, high-speed, and fully reconfigurable microwave systems.

GeSn-on-Si avalanche photodiodes (APDs) are emerging as a promising solution for low-light detection in the short-wave infrared (SWIR) spectral range, including applications in imaging and telecommunications. In this work, key challenges such as high dark current and limited responsivity are addressed by demonstrating devices, which combine low noise with high signal amplification, while remaining compatible with silicon-based technology. GeSn-on-Si APDs with various Sn concentrations up to 1.9% are fabricated and characterized. The GeSn layers are grown pseudomorphically on Ge virtual substrates on Si wafers using molecular beam epitaxy. The devices comprise a double-mesa structure and exhibit a dark current dominated by a perimeter leakage path, independent of the Sn content. A dark current below 1 µA is maintained up to the onset of avalanche breakdown, marking a significant improvement compared to prior work. A record-high responsivity of 14.7 A W⁻¹ is achieved at 1550 nm for the APD with 1.9% Sn. Through impulse response measurements, the 3-dB bandwidth is determined to 1.2 GHz on devices with an 80 µm diameter, resulting in a responsivity-bandwidth-product of 17.6 A W⁻¹ GHz⁻¹. These results highlight the potential of GeSn-on-Si APDs for high-performance, low-light applications in the SWIR range.