Anisotropic Temperature Dependent Band Shift in Layered Black Phosphorus

Abstract Temperature acts as a control lever for the electronic band structure in black phosphorus (BP), significantly influencing its device performance. While the effects of electron‐phonon coupling and lattice thermal expansion on the temperature‐dependent band gap are well understood, there have been no reports on the electronic band as a function of temperature. Additionally, although black phosphorus is well‐known for its significant anisotropic optoelectronic properties, there is comparatively less understanding regarding how various lattice constants affect the electronic band in response to temperature changes. Herein, temperature dependence of the valence band of BP has been measured by angle‐resolved photoelectron spectroscopy (ARPES) and the band shifts are quantitatively characterized. The band shift along the k x direction is larger than that along the k y direction upon heating from 10 to 200 K even if changing the photon energy. It is certified that the band shifts are primarily attributed to the lattice expansion across different crystal orientations, as determined by density functional theory (DFT) calculations. This study investigates the anisotropic temperature dependence of the electronic band shift in black phosphorus, revealing the underlying mechanisms. These findings will be instrumental in guiding the rational design of BP‐based devices tailored for operation across a range of temperatures.