Two-dimensional ambipolar carriers of giant density at the diamond/cubic-BN(111) interfaces: toward complementary logic and quantum applications.

The extremely difficult ambipolar doping activation greatly hinders the outstanding performance of diamond for electronic devices. The main concern has been devoted to surface conduction by two-dimensional (2D) carriers. 2D hole gas (2DHG) in the diamond is induced by surface transfer doping dominated by the adsorbate's status and faces stability issues. Meanwhile, a feasible way to generate the other essential ambipolar carrier-2D electron gas (2DEG) is still lacking. We propose that the well-lattice-matched diamond/cBN(111) interfaces can spontaneously induce 2D ambipolar carriers with a giant density of 4.17 × 1014 cm-2, an order higher than other competitors. 2DEG and 2DHG can be separately achieved near the hetero-interfaces consisting of C-N and C-B bonds, respectively. Interestingly, the robust 2D charges are derived from a novel bulk-induced polarization-discontinuity at the interfaces, which can be attributed to an unexpected non-zero formal polarization of centrosymmetric cBN along the [111] direction. The existence of 2D ambipolar carriers at the diamond/cBN(111) interfaces has resolved the missing n-type conduction in diamond, thus opening up possibilities for complementary logic applications. Additionally, the high density of quantum-confined 2D ambipolar carriers provides an excellent platform for strongly correlated systems, which could lead to novel quantum information processing applications.

Strong selective oxidization on two-dimensional GaN: a first principles study.

Ab initio calculations were performed to investigate the chemical oxidation of two-dimensional (2D) gallium nitride (GaN). The nitrogen surface was found to form a metastable configuration under oxygen adsorption, while the gallium surface could be readily transformed to a more stable configuration of HO-GaN-H with an exceptionally low energy barrier. The results also revealed that the adsorption of oxygen adatoms resulted in the reduction of work-function and induced the change from 2D GaN to a new GaNO compound. Our findings indicate that we should pay attention to the oxidation effect of 2D GaN in practical device applications.

High-Performance Two-Dimensional InSe Field-Effect Transistors with Novel Sandwiched Ohmic Contact for Sub-10 nm Nodes: a Theoretical Study.

Two-dimensional (2D) InSe-based field effect transistor (FET) has shown remarkable carrier mobility and high on-off ratio in experimental reports. Theoretical investigations also predicated the high performance can be well preserved at sub-10 nm nodes in the ballistic limit. However, both experimental experience and theoretical calculations pointed out achieving high-quality ohmic has become the main limiting factor for high-performance 2D FET. In this work, we proposed a new sandwiched ohmic contact with indium for InSe FET and comprehensively evaluated its performance from views of material and device based on ab initio methods. The material properties denote that all of fundamental issues of ohmic contact including tunneling barrier, the Schottky barrier, and effective doping are well concerned by introducing the sandwiched structure, and excellent contact resistance was achieved. At device performance level, devices with gate length of 7, 5, and 3 nm were investigated. All metrics of sandwiched contacted devices far exceed requirement of the International Technology Roadmap for Semiconductors (ITRS) and exhibit obvious promotion as compared to conventional structures. Maximum boost of current with 69.4%, 50%, and 49% are achieved for devices with 7, 5, and 3 nm gate length, respectively. Meanwhile, maximum reduction of the intrinsic delay with 20.4%, 16.7%, and 18.9% are attained. Moreover, a benchmark of energy-delay product (EDP) against other 2D FETs is presented. All InSe FETs with sandwiched ohmic contact surpass MoS2 FETs as well as requirement from ITRS 2024. The best result approaches the upper limit of ideal BP FET, denoting superior preponderance of sandwiched structures for InSe FETs in the next generation of complementary metal-oxide semiconductor (CMOS) technology.

High Performance Drain Engineered InGaN Heterostructure Tunnel Field Effect Transistor.

A drain engineered InGaN heterostructure tunnel field effect transistor (TFET) is proposed and investigated by Silvaco Atlas simulation. This structure uses an additional metal on the drain region to modulate the energy band near the drain/channel interface in the drain regions, and increase the tunneling barrier for the flow of holes from the conduction band of the drain to the valence band of the channel region under negative gate bias for n-TFET, which induces the ambipolar current being reduced from 1.93 × 10-8 to 1.46 × 10-11 A/µm. In addition, polar InGaN heterostructure TFET having a polarization effect can adjust the energy band structure and achieve steep interband tunneling. The average subthreshold swing of the polar drain engineered heterostructure TFET (DE-HTFET) is reduced by 53.3% compared to that of the nonpolar DE-HTFET. Furthermore, ION increases 100% from 137 mA/mm of nonpolar DE-HTFET to 274 mA/mm of polar DE-HTFET.