Strong anisotropy and layer-dependent carrier mobility of two-dimensional semiconductor ZrGeTe4

Sun light driven isotropy β-Bi2O3 with high charge-carrier mobility for efficient degradation of bisphenol A and phenol

Nanostructure β-Bi2O3 was synthesized and used for the photocatalytic degradation of bisphenol A and phenol. After 90 minutes of sun light irradiation, the degradation efficiencies of bisphenol A and phenol...

Visible to Short-Wave Infrared Photodetectors Based on ZrGeTe4 van der Waals Materials

The self-terminated, layered structure of van der Waals materials introduces fundamental advantages for infrared (IR) optoelectronic devices. These are mainly associated with the potential for low noise while maintaining high internal quantum efficiency when reducing IR absorber thicknesses. In this study, we introduce a new van der Waals material candidate, zirconium germanium telluride (ZrGeTe₄), to a growing family of promising IR van der Waals materials. We find the bulk form ZrGeTe₄ has an indirect band edge around ∼0.5 eV, in close agreement with previous theoretical predictions. This material is found to be stable up to 140 °C and shows minimal compositional variation even after >30 days storage in humid air. We demonstrate simple proof-of-concept broad spectrum photodetectors with responsivities above 0.1 AW^-1 across both the visible and short-wave infrared wavelengths. This corresponds to a specific detectivity of ∼10⁹ cm Hz^1/2 W^-1 at λ = 1.4 μm at room temperature. These devices show a linear photoresponse vs illumination intensity relationship over ∼4 orders of magnitude, and fast rise/fall times of ∼50 ns, also verified by a 3 dB roll-off frequency of 5.9 MHz. As the first demonstration of photodetection using ZrGeTe₄, these characteristics measured on a simple proof-of-concept device show the exciting potential of the ZrGeTe₄ for room temperature IR optoelectronic applications.

Electronic structures and anisotropic carrier mobilities of monolayer ternary metal iodides MLaI5(M=Mg, Ca, Sr, Ba)

Exploiting two-dimensional (2D) materials with natural band gaps and anisotropic quasi-one-dimensional (quasi-1D) carrier transport character is essential in high-performance nanoscale transistors and photodetectors. Herein, the stabilities, electronic structures and carrier mobilities of 2D monolayer ternary metal iodides MLaI₅(M = Mg, Ca, Sr, Ba) have been explored by utilizing first-principles calculations combined with numerical calculations. It is found that exfoliating MLaI₅monolayers are feasible owing to low cleavage energy of 0.19-0.21 J m^-2and MLaI₅monolayers are thermodynamically stable based on phonon spectra. MLaI₅monolayers are semiconductors with band gaps ranging from 2.08 eV for MgLaI₅to 2.51 eV for BaLaI₅. The carrier mobility is reasonably examined considering both acoustic deformation potential scattering and polar optical phonon scattering mechanisms. All MLaI₅monolayers demonstrate superior anisotropic and quasi-1D carrier transport character due to the striped structures. In particular, the anisotropic ratios of electron and hole mobilities along different directions reach hundreds and tens for MLaI₅monolayers, respectively. Thus, the effective electron-hole spatial separation could be actually achieved. Moreover, the absolute locations of band edges of MLaI₅monolayers have been aligned. These results would provide fundamental insights for MLaI₅monolayers applying in nano-electronic and optoelectronic devices.