Dr. Albert Davydov from Materials Science and Engineering Division, National Institute of Standards and Technology, will give a seminar titled "Crystal Growth and Doping of 2D Materials for Advanced Electronics" to the interested faculty and students at Discovery Park.

Abstract

Layered van-der-Waals 2D materials, such as graphene and metal chalcogenides, are being extensively studied for beyond CMOS scaling limits applications, such as sub-1-nm thick channels for the Front-End-of-Line transistors and complimentary logic devices for the Back-End-of-Line integration. To realize these potentials, multiple material challenges must be overcome - from wafer-scale fabrication of high quality 2D layers, reduction of contact resistance, controllable doping, etc. Focusing on the latter, the ability to manipulate electrical properties by controllable doping 2D semiconductors opens a possibility for fabricating ultra-thin p/n junctions and other two-dimensional and hybrid electronic devices. However, reliable processes for reproducible doping of 2D materials are yet to be developed.

This talk will survey various doping approaches of 2D semiconductors from substitutional to electrostatic to charge-transfer, followed by the specific example of developing controllable doping of indium selenide layers. The n- and p- type substitutional doping of InSe was conducted via single crystal Bridgman growth using Sn and Zn impurities, respectively. The concentration of Sn atoms in progressively doped n-type InSe samples varied from tens to hundreds of ppm as estimated from inductively coupled plasma mass-spectrometry (ICP-MS). Electrically-active dopant concentration was evaluated by van-der-Pauw Hall measurements and compared against the total Sn concentration in the InSe matrix. The talk will conclude with utilizing controllable doping of InSe layers for a demonstration of p-InSe/n-InSe homojunction photodetector [1] and gate-tunable n-InSe/p-Si heterojunction tunnel triode [2].

References:
1. C. Patil et al., Self-driven highly responsive pn junction InSe heterostructure near-IR light detector, Photonics Research 10 (2022) A97
2. J. Miao et al., Heterojunction tunnel triodes based on two-dimensional metal selenide and three-dimensional silicon, Nature Electronics 5 (2022) 744

Biography

Albert Davydov is a leader of Functional Nanostructured Materials Group at NIST, which focuses on materials and processes for advanced electronics, magnetics, energy, and catalysis. Albert received PhD in Chemistry from Moscow State University. He joined NIST in 2005. His research interests include fabrication, processing, and microstructural characterization of a wide range of electronic materials including semiconductor nanowires, 2D and quantum materials. His expertise also includes thermodynamic modeling and experimental study of phase diagrams for metal and semiconductor material systems.

He serves as a Head of the Semiconductor Task Group for the International Centre for Diffraction Data (ICDD), Project Lead on Quantum Phenomena Terminology at the International Organization for Standardization (ISO); member of Advisory Board with the Applied Physics Review journal, co-Chair of the Reference Materials Task Group at ASTM Subcommittee on Compound Semiconductors, and co-Chair of SPIE Optics & Photonics Conference on Low-dimensional Materials and Devices.