Journal
ADVANCED MATERIALS TECHNOLOGIES
Volume 7, Issue 1, Pages -Publisher
WILEY
DOI: 10.1002/admt.202100912
Keywords
black germanium; enhanced responsivity; external quantum efficiency; metal-semiconductor-metal photodetector; reactive ion etching
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Funding
- ASTAR Singapore, Advanced Manufacturing and Engineering (AME) Young Individual Research Grant (YIRG) [A2084c0066]
- Ministry of Education Singapore, under the Grant ACRF Tier 2 grant [T2EP50120-0003]
- Nanyang NanoFabrication Centre (N2FC)
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The study demonstrates a method to fabricate high-performance Ge photodetectors on black Ge surface, achieving significant enhancement in light absorption through reducing reflection and introducing internal gain.
In this work, a viable method is demonstrated to realize high-performance germanium (Ge) photodetectors (PDs) on the nanostructured Ge surface, namely black Ge, formed by chlorine (Cl-2) gas-based reactive ion etching at room temperature. Black Ge surface has spike-like pyramidal structures with a width and height up to 150 and 570 nm, respectively. Average reflection of black Ge is reduced to 2% at a wavelength range from 1 to 2 mu m, while that of planar Ge is approximate to 37%. Light absorption is strongly enhanced by the significantly reduced reflection, thereby leading to an increase in responsivity of black Ge PDs. Moreover, external quantum efficiency (EQE) exceeds 160% at 1550 nm, indicating the existence of internal gain resulted from multiple carrier generation in Ge nanostructures. Therefore, this work provides an effective and reliable approach to significantly enhance photodetection performance of Ge-based optoelectronic devices.
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