Extrinsic Photoconduction Induced Short‐Wavelength Infrared Photodetectors Based on Ge‐Based Chalcogenides

Abstract

2D layered photodetectors have been widely researched for intriguing optoelectronic properties but their application fields are limited by the bandgap. Extending the detection waveband can significantly enrich functionalities and applications of photodetectors. For example, after breaking through bandgap limitation, extrinsic Si photodetectors are used for short-wavelength infrared or even long-wavelength infrared detection. Utilizing extrinsic photoconduction to extend the detection waveband of 2D layered photodetectors is attractive and desirable. However, extrinsic photoconduction has yet not been observed in 2D layered materials. Here, extrinsic photoconduction-induced short-wavelength infrared photodetectors based on Ge-based chalcogenides are reported for the first time and the effectiveness of intrinsic point defects are demonstrated. The detection waveband of room-temperature extrinsic GeSe photodetectors with the assistance of Ge vacancies is broadened to 1.6 µm. Extrinsic GeSe photodetectors have an excellent external quantum efficiency (0.5%) at the communication band of 1.31 µm and polarization-resolved capability to subwaveband radiation. Moreover, room-temperature extrinsic GeS photodetectors with a detection waveband to the communication band of 1.55 µm further verify the versatility of intrinsic point defects. This approach provides design strategies to enrich the functionalities of 2D layered photodetectors.

Breaking the Cut‐Off Wavelength Limit of GaTe through Self‐Driven Oxygen Intercalation in Air

“…The obtained dichroic ratio here is compatible with previous polarization‐sensitive photodetectors. [ 10b ] The angle‐dependence of the extrinsic photoconductivity is slightly sample‐dependent, which is attributed to the O 2 intercalation induced disorder and grain reorientation. [ 16a ] The most likely reason for the anisotropy in the photocurrent is anisotropic optical absorption due to the anisotropy on the refractive index.…”

“…The ability to break through the bandgap limitation is of great significance for practical optical and optoelectronic device applications. [ 10 ] A few techniques have already been proposed to broaden the detection waveband of silicon via strain engineering, [ 10a ] the addition of dopants. [ 11 ] While, for 2D semiconductors, the atomic thickness and dangling bonds free surface allow significant bandgap modifications through strain engineering, [ 12 ] defects, [ 10b ] layer number control, [ 13 ] alloying, [ 14 ] as well as intercalation.…”

“…[ 10 ] A few techniques have already been proposed to broaden the detection waveband of silicon via strain engineering, [ 10a ] the addition of dopants. [ 11 ] While, for 2D semiconductors, the atomic thickness and dangling bonds free surface allow significant bandgap modifications through strain engineering, [ 12 ] defects, [ 10b ] layer number control, [ 13 ] alloying, [ 14 ] as well as intercalation. [ 15 ] Recently, short‐wavelength infrared photodetectors have already been reported using germanium (Ge)‐based chalcogenides, with the absorption cut‐off extended to the higher wavelength via intrinsic point defects.…”

“…[ 15 ] Recently, short‐wavelength infrared photodetectors have already been reported using germanium (Ge)‐based chalcogenides, with the absorption cut‐off extended to the higher wavelength via intrinsic point defects. [ 10b ]…”

Next‐generation machine vision systems incorporating two‐dimensional materials: Progress and perspectives

“…Many factors may influence the growth of high‐quality large‐area 2D materials, such as elemental ratio, surface defects, nucleation processes, growth catalytic techniques, and phase control, require further investigation. Because of the immature state of growth technology, defects are produced in the material: vacancies, substitutions, anti‐sites, and adsorbed atoms 54 . These have a significant influence on the electrical and optoelectronic properties of 2D materials: they can act as carrier donors, scatterers, traps, and recombination centers under different conditions 55 .…”