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• WSe 2 /SnSe 2 TFET with TiO 2 dielectric exhibits on-state current of 1560 μA/μm. • High- k gate dielectric materials lead to a decline in tunneling length. • The underlap structure leads to a reduction in on-state current. • Combination of heterostructures with high- k gate dielectric materials is an effective way of improving TFET performance. Combining two-dimensional materials and high- k gate dielectrics offers a promising way to enhance the device performance of tunneling field-effect transistor (TFET). In this work, the device performance of WSe 2 /SnSe 2 TFET with various gate dielectric materials is investigated based on quantum transport simulation. Results show that TFETs with high- k gate dielectric materials exhibit improved on-off ratio and enhanced transconductance. The optimized WSe 2 /SnSe 2 TFET with TiO 2 gate dielectrics achieves an on-state current of 1560 μA/μm and a subthreshold swing (SS) of 48 mV/dec. The utilization of high- k gate dielectric materials results in shorter tunneling length, higher transmission efficiency, and increased electron tunneling probability. The performance of the WSe 2 /SnSe 2 TFET would be affected by the presence of the underlap region. Moreover, WSe 2 /SnSe 2 TFETs with La 2 O 3 dielectric can be scaled down to 3 nm while meeting high-performance (HP) device requirements according to the International Technology Roadmap for Semiconductors (ITRS). This research presents a practical solution for designing advanced logic devices in the sub-5 nm technology node. [Display omitted] [ABSTRACT FROM AUTHOR]

• H-diamond surfaces have considerable potential for the field of electronic devices by virtue of the capability to form a high density of 2DHG. • The mechanism for the formation of 2DHG on H-diamond surfaces has not been completely elucidated as yet. • We establish ingenious theoretical models and provide compelling theoretical insight into the surface transfer doping model. • An interface with negative charges can induce an upward band bending on the H-diamond side. The surface transfer doping model has been extensively adopted as a mechanism to account for the generation of hole accumulation layers below hydrogen-terminated diamond (H-diamond) surfaces. To achieve effective surface transfer doping, surface electron acceptor materials with high electron affinity (EA) are required to produce a high density of two-dimensional hole gas (2DHG) on the H-diamond subsurface. We have established ingenious theoretical models to demonstrate that even if these solid materials do not have a high EA value, they remain capable of absorbing electrons from the H-diamond surface by forming a negatively charged interface to act as a surface electron acceptor in the surface transfer doping model. Our calculations, particularly for the local density of states, provide compelling evidence that the effect of an interface with negative charges induces an upward band bending on the H-diamond side. Furthermore, the valence band maximum of the diamond atoms at the interface crosses the Fermi level, giving rise to strong surface transfer p-type doping. These results give a strong theoretical interpretation of the origin of 2DHG on H-diamond surfaces. The proposed guidelines contribute to further improvements in the performance of 2DHG H-diamond field effect transistors. [Display omitted] [ABSTRACT FROM AUTHOR]

Transparent conductive materials (TCMs) has always been playing a significant role in electronic and photovoltaic area, due to its prominent optical and electronic properties. To render those transparent materials highly conductive, efficient n- and p- type doping is critically needed to obtain high concentration of free electron and hole carriers. Despite extensive research over the past five decades, high-quality p-type doping of wide-band-gap transparent materials remains a challenge. Here, we summarize four proposed design principles to enhance the p-type conductivity of these wide band gap materials, including (i) reducing the formation energy of the acceptors to enhance the dopant concentration; (ii) lowering the ionization energy and, hence, increasing the ionization of the acceptors to increase the concentration of the free holes; (iii) increasing the VBM of the host material to approaching the pinned Fermi level; and (iv) suppressing the compensating donors to shifting the pinning Fermi level toward the VBM. For each mechanism, we discuss in detail its underlying physics and provided some examples to illustrate the design principles. From this review, one could learn the doping principles and have a strategic mind when designing other p-type materials.

The use of an interfacial passivation layer is one important strategy for achieving a high quality interface between high-kand III–V materials integrated into high-mobility metal–oxide–semiconductor field-effect transistor (MOSFET) devices. Here, we propose gallium nitride (GaN) as the interfacial layer between III–V materials and hafnium oxide (HfO2). Utilizing first-principles calculations, we explore the structural and electronic properties of the GaN/HfO2interface with respect to the interfacial oxygen contents. In the O-rich condition, an O8 interface (eight oxygen atoms at the interface, corresponding to 100% oxygen concentration) displays the most stability. By reducing the interfacial O concentration from 100 to 25%, we find that the interface formation energy increases; when sublayer oxygen vacancies exist, the interface becomes even less stable compared with O8. The band offset is also observed to be highly dependent on the interfacial oxygen concentration. Further analysis of the electronic structure shows that no interface states are present at the O8 interface. These findings indicate that the O8 interface serves as a promising candidate for high quality III–V MOS devices. Moreover, interfacial states are present when such interfacial oxygen is partially removed. The interface states, leading to Fermi level pinning, originate from unsaturated interfacial Ga atoms.