Controlled thin film etching is essential for future semiconductor devices, especially with complex high aspect ratio structures. Therefore, self-limiting atomic layer etching processes are of great interest to the semiconductor industry. In this work, a process for atomic layer etching of aluminum oxide (Al2O3) films using sequential and self-limiting thermal reactions with trimethylaluminum and hydrogen fluoride as reactants was demonstrated.
Jun Yang, Amin Bahrami, Xingwei Ding, Sebastian Lehmann, Nadine Kruse, Shiyang He, Bowen Wang, Martin Hantusch, Kornelius Nielsch ZnO thin films are deposited by atomic layer deposition (ALD) using diethylzinc as the Zn source and H2O and H2O2 as oxygen sources. The oxidant- and temperature-dependent electrical properties and growth characteristics are systematically investigated. Materials analysis … Weiterlesen
Surface modification may significantly improve the performance of thermoelectric materials by suppressing thermal conductivity. Using the powder atomic layer deposition method, the newly developed Sb2O5 thin films produced from SbCl5 and H2O2 were formed on the surfaces of Bi powders. Because of the high thermal resistance generated by Sb2O5 layers on Bi particles, a substantial decrease in κtot from 7.8 to 5.7 W m–1 K–1 was obtained with just 5 cycles of Sb2O5 layer deposition and a 16% reduction in κlat. Because of the strong phonon scattering, the maximum zT values increased by around 12% and were relocated to 423 K.
SbOx thin films are deposited by atomic layer deposition (ALD) using SbCl5 and Sb(NMe2)3 as antimony reactants and H2O and H2O2 as oxidizers at low temperatures. SbCl5 can react with both oxidizers, while no deposition is found to occur using Sb(NMe2)3 and H2O. For the first time, the reaction mechanism and dielectric properties of ALD-SbOx thin films are systematically studied, which exhibit a high breakdown field of ≈4 MV/cm and high areal capacitance ranging from 150 to 200 nF/cm², corresponding to a dielectric constant ranging from 10 to 13. The ZnO semiconductor layer is integrated into a SbOx dielectric layer, and thin film transistors (TFTs) are successfully fabricated. A TFT with a SbOx dielectric layer deposited at 200 °C from Sb(NMe2)3 and H2O2 presents excellent performance, such as a field effect mobility (µ) of 12.4 cm²/V∙s, Ion/Ioff ratio of 4∙10^8, subthreshold swing of 0.22 V/dec, and a trapping state (Ntrap) of 1.1∙10^12 1/eV∙cm². The amorphous structure and high areal capacitance of SbOx boosts the interface between the semiconductor and dielectric layer of TFT devices and provide a strong electric field for electrons to improve the device mobility.
Following the nice discussions at the EFDS „Simulations for ALD“ workshop organized online March 2021, a workshop on modelling atomic layer processes will be held in Linköping, Sweden 15-16 March 2022. The meeting format will be hybrid with possibility to join both on-site and online. We hope to meet you then and discuss state-of-the-art methods and current thresholds to jointly bring the field forward!
In thermoelectric materials, phase boundaries are crucial for carrier/phonon transport. Manipulation of carrier and phonon scatterings by introducing continuous interface modification has been shown to improve thermoelectric performance. In this paper, a strategy of interface modification based on powder atomic layer deposition (PALD) is introduced to accurately control and modify the phase boundary of pure bismuth. Ultrathin layers of Al2O3, TiO2, and ZnO are deposited on Bi powder by typically 1–20 cycles. All of the oxide layers significantly alter the microstructure and suppressed grain growth. These hierarchical interface modifications aid in the formation of an energy barrier by the oxide layer, resulting in a substantial increase in the Seebeck coefficient that is superior to that of most pure polycrystalline metals. Conversely, taking advantage of the strong electron and phonon scattering, an exceptionally large decrease in thermal conductivity is obtained. A maximum figure of merit, zT, of 0.15 at 393 K and an average zT of 0.14 at 300–453 K were achieved in 5 cycles of Al2O3-coated Bi. The ALD-based approach, as a practical interfacial modification technique, can be easily applied to other thermoelectric materials, which can contribute to the development of high-performance thermoelectric materials of great significance.