Electronic transport characteristics and nanodevice designs for β-HfNCl monolayer.

• The β -HfNCl monolayer has isotropic mechanical properties. • The pn -junction diodes and pin -junction field-effect transistors of β -HfNCl monolayer have strong rectification effect and electrical anisotropy. • The pin -junction field-effect transistors of β -HfNCl monolayer show an obvious field-effect behavior. • The pin -junction phototransistors β -HfNCl monolayer have a strong response to ultraviolet light. The mechanical properties, electronic structure, electric transport and optoelectronic properties of a recently predicted wide bandgap semiconductor β -HfNCl monolayer are systematically studied by means of first-principles calculations. β -HfNCl monolayer is isotropic in mechanical properties, whose calculated Young's modulus, shear modulus, and layer modulus of β -HfNCl monolayer are 128.9–129.2, 44.28, and 119.46 N m⁻¹, respectively. An appropriate tensile strain (i.e., beyond 3 %) can induce a transition from indirect bandgap to direct bandgap. In addition, we construct several conceptual nanodevice structures based on β -HfNCl monolayer, such as pn- junction diodes, pin- junction field-effect transistors (FETs) and phototransistors. The electronic transport results reveal that the pn- junction diodes have obvious rectification effect and strong electric anisotropy. Their rectification ratios and electric anisotropy ratio (η) can reach up to 10⁶ and 3.69, respectively. The FETs have an obvious field-effect behavior with a slightly lower rectification ratio (1 0 ⁵). Moreover, we investigate the photoelectric response of the phototransistors of β -HfNCl monolayer under the illumination of light. They have a strong response to the light whose energy is larger than the violet light, indicating that the β -HfNCl monolayer can be a platform to detect the ultraviolet light. These findings provide crucial insights into the potential applications of β -HfNCl monolayer in electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]