High Electric Field Carrier Transport and Power Dissipation in Multilayer Black Phosphorus Field Effect Transistor with Dielectric Engineering

TL;DR

This paper investigates high electric field transport and power dissipation in multilayer black phosphorus FETs, demonstrating how dielectric engineering with hBN improves thermal management and device endurance compared to SiO2 substrates.

Contribution

It introduces a size-dependent electro-thermal model and shows that using hBN as a dielectric enhances breakdown power density and thermal spreading in black phosphorus transistors.

Findings

Maximum current density of 3.3 x 10^10 A/m^2 at 5.58 MV/m

Interfacial thermal conductance of 1-10 MW/m^2 K for BP-dielectric interfaces

Threefold increase in breakdown power density with hBN dielectric

Abstract

This study addresses high electric field transport in multilayer black phosphorus (BP) field effect transistors (FETs) with self-heating and thermal spreading by dielectric engineering. Interestingly, we found that multilayer BP device on a SiO2 substrate exhibited a maximum current density of 3.3 x 10E10 A/m2 at an electric field of 5.58 MV/m, several times higher than multilayer MoS2. Our breakdown thermometry analysis revealed that self-heating was impeded along BP-dielectric interface, resulting in a thermal plateau inside the channel and eventual Joule breakdown. Using a size-dependent electro-thermal transport model, we extracted an interfacial thermal conductance of 1-10 MW/m2 K for the BP-dielectric interfaces. By using hBN as a dielectric material for BP instead of thermally resistive SiO2 (about 1.4 W/m K), we observed a 3 fold increase in breakdown power density and a relatively higher electric field endurance together with efficient and homogenous thermal spreading because hBN had superior structural and thermal compatibility with BP. We further confirmed our results based on micro-Raman spectroscopy and atomic force microscopy, and observed that BP devices on hBN exhibited centrally localized hotspots with a breakdown temperature of 600K, while the BP device on SiO2 exhibited a hotspot in the vicinity of the electrode at 520K.