TY - JOUR
T1 - Carrier Dynamics and Absorption Properties of Gold-Hyperdoped Germanium
T2 - Insight into Tailoring Defect Energetics
AU - Dissanayake, Sashini Senali
AU - Ferdous, Naheed
AU - Gandhi, Hemi H.
AU - Pastor, David
AU - Tran, Tuan T.
AU - Williams, Jim S.
AU - Aziz, Michael J.
AU - Mazur, Eric
AU - Ertekin, Elif
AU - Sher, Meng Ju
N1 - Funding Information:
H.H.G. acknowledges support from the Department of Defense (DoD) under Grant Nos. DGE 0946799 through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program and the Directed Energy Processing Society Graduate Fellowship. D.P. acknowledges financial support from the MEC within Programa Nacional de movilidad de recursos humanos del Plan Nacional I+D+i 2008-2011 (EX-2010-0662),the program Ramón y Cajal (RYC-2014-16936) and from the Spanish ministry of Science, Innovation and Universities (MICINN) under contract no. TEC2017-84378-R. This work is part of the project MADRID-PV2 P-2018/EMT-4308 funded by the Regional Government of Madrid with support from FEDER funds. This work was also supported by the US Air Force Office of Scientific Research (FA9550-14-1-0150). This work was performed in part at the Harvard Center for Nanoscale Systems (CNS), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the National Science Foundation under NSF award no. ECS-0335765.
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/6
Y1 - 2021/6
N2 - Hyperdoping germanium with gold is a potential method to produce room-temperature short-wavelength-infrared radiation (SWIR; 1.4-3.0μm) photodetection. We investigate the charge carrier dynamics, light absorption, and structural properties of gold-hyperdoped germanium (Ge:Au) fabricated with varying ion implantation and nanosecond pulsed laser melting conditions. Time-resolved terahertz spectroscopy (TRTS) measurements show that Ge:Au carrier lifetime is significantly higher than that in previously studied hyperdoped silicon systems. Furthermore, we find that lattice composition, sub-band-gap optical absorption, and carrier dynamics depend greatly on hyperdoping conditions. We use density functional theory (DFT) to model dopant distribution, electronic band structure, and optical absorption. These simulations help explain experimentally observed differences in optical and optoelectronic behavior across different samples. DFT modeling reveals that substitutional dopant incorporation has the lowest formation energy and leads to deep energy levels. In contrast, interstitial or dopant-vacancy complex incorporation yields shallower energy levels that do not contribute to sub-band-gap light absorption and have a small effect on charge carrier lifetimes. These results suggest that it is promising to tailor dopant incorporation sites of Ge:Au for SWIR photodetection applications.
AB - Hyperdoping germanium with gold is a potential method to produce room-temperature short-wavelength-infrared radiation (SWIR; 1.4-3.0μm) photodetection. We investigate the charge carrier dynamics, light absorption, and structural properties of gold-hyperdoped germanium (Ge:Au) fabricated with varying ion implantation and nanosecond pulsed laser melting conditions. Time-resolved terahertz spectroscopy (TRTS) measurements show that Ge:Au carrier lifetime is significantly higher than that in previously studied hyperdoped silicon systems. Furthermore, we find that lattice composition, sub-band-gap optical absorption, and carrier dynamics depend greatly on hyperdoping conditions. We use density functional theory (DFT) to model dopant distribution, electronic band structure, and optical absorption. These simulations help explain experimentally observed differences in optical and optoelectronic behavior across different samples. DFT modeling reveals that substitutional dopant incorporation has the lowest formation energy and leads to deep energy levels. In contrast, interstitial or dopant-vacancy complex incorporation yields shallower energy levels that do not contribute to sub-band-gap light absorption and have a small effect on charge carrier lifetimes. These results suggest that it is promising to tailor dopant incorporation sites of Ge:Au for SWIR photodetection applications.
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U2 - 10.1103/PhysRevApplied.15.064058
DO - 10.1103/PhysRevApplied.15.064058
M3 - Article
AN - SCOPUS:85108956617
SN - 2331-7019
VL - 15
JO - Physical Review Applied
JF - Physical Review Applied
IS - 6
M1 - 064058
ER -