Diamond is semiconductor with unique properties and is under development to be employed in robust transistors. This study of Borophene and BC3 provides insight on their potential as acceptor layers over Hydrogenterminated diamond (100) (H-diamond(100))for use in diamond-based electronics. Boron-based 2D materials such as Borophene and BC3 resemble h-BN and graphene. While there has been significant recent interest in the distinctive structural and electronic properties of h-BN and graphene when interfaced with diamond surfaces, owing to their acceptor-like and contact-like characteristics, the structural and electronic interactions of borophene and BC3 with diamond in the formation of 2D/3D heterostructures remain unexplored. The goal of this work is to determine the structural and electronic properties of hydrogen terminated diamond 100 with borophene and BC3. This study used Density functional theory (DFT) calculations with Perdew–Burke-Ernzerhof(PBE) functional as implemented in GPAW and ASE framework to analyze structural and electronic properties. 2D-layers were optimized over H-diamond(100) and band structure calculation was conducted. An attempt is also made to compare the structural and electronic properties of Borophene/Diamond and BC3/Diamond heterostructures to relatively well-known hBN/Diamond heterostructure.
High power radio frequency (RF) transfer-doped diamond field effect transistors (FETs) are being fabricated at the Army Research Laboratory (ARL). To implement these into radar systems we have a parallel effort to extract accurate compact models from their measured DC and RF data. At this early stage we are using the commercially available Angelov model and will discuss fitting the model parameters and how their parameter values differ from GaN and GaAs FETs. Results indicate good model prediction of measured results in some cases. Also, model extraction can indicate areas of the device that needs greater attention for improved performance such as the access region resistance. Furthermore, in the saturation region of operation these transistors exhibit a hole saturation velocity of 5 × 106 cm/s obtained from extracted model parameters.
Army Research Laboratory (ARL) is developing radio frequency (RF) field-effect-transistors (FETs) on hydrogen-terminated, single-crystal diamond surfaces. By employing advanced fabrication methods, we achieve state-of-the-art device performance with gate lengths below 100 nm. We are exploring methods to improve the stability of fabricated FETs, which is critical for maturation of the technology and its commercial acceptance. DC and RF measurement data will be reviewed and discussed within the framework of improving device yield and reliability.
Surface induced transfer doping (SITD) is a novel, highly efficiency doping technique that is being used to invoke the p-type surface conductivity of intrinsic diamond for high-frequency, high-power electronic devices. In the SITD process, a high electron affinity (EA) thin film acceptor layer is interfaced with the hydrogenated diamond surface with negative electron affinity (NEA) to induce the effective p-type doping on the diamond surface. Overall, device performance of the SITD doped devices is contingent on the type and quality of the interface between the acceptor layer and hydrogenated diamond surfaces. Motivated by this, our internal theoretical modeling efforts based on a hybrid approach of machine learning and first principle calculations have focused on performing bottom-up design of novel acceptor layers with higher stability and improved device performance, e.g., doped TMOs and 2D layer. In this talk, recent results from our predictive modeling effort will be presented.
The electronic structure and optical properties of Ge-core/Si-shell nanocrystal or quantum dot (QD) are investigated
using the atomistic tight binding method as implemented in NEMO3D. The thermionic lifetime that
governs the hole leakage mechanism in the Ge/Si QD based laser, as a function of the Ge core size and strain, is
also calculated by capturing the bound and extended eigenstates, well below the band edges. We also analyzed
the eect of core size and strain on optical properties such as transition energies and transition rates between
electron and hole states. Finally, a quantitative and qualitative analysis of the leakage current due to the hole
leakage through the Ge-core/Si-shell QD laser, at dierent temperatures and Ge core sizes, is presented.
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