Broadband visible-to-telecom wavelength germanium quantum dot photodetectors

Abstract

Germanium (Ge) quantum dot (QD) photodetectors (PDs) were fabricated on Ge substrates exhibiting a broadband, visible to near-infrared (near-IR) photoresponse in the k ¼ 400-1550 nm range. Room-temperature responsivities (R sp) up to 1.12 A/W and internal quantum efficiency IQE ¼ 313% were obtained, superior to conventional silicon and germanium photodiodes. Noise analysis was performed at visible k ¼ 640 nm and telecom k ¼ 1550 nm wavelengths, both yielding room-temperature specific detectivity D* ' 2 Â 10 10 cm Hz 1/2 W À1. Lowering the operating temperature and incident power led to sharply enhanced performance, with D * ¼ 1.1 Â 10 12 cm Hz 1/2 W À1 and IQE ¼ 1000% at T ¼ 100 K for an incident power of 10 nW at k ¼ 1550 nm. Based on their simple fabrication and silicon technology compatibility, these Ge QD PDs represent a promising alternative for broadband, high-performance visible to near-IR detection.

Ge nanoparticles in SiO2 for near infrared photodetectors with high performance

“…The high internal IQE in our samples can been explained by considering trapping of the photogenerated holes on Ge related defects/traps. Higher than 100% quantum efficiency is also reported by other groups 3,42–44 .…”

“…In the last decade, many research groups have paid attention on amorphous germanium nanoparticles (Ge-NPs) embedded in different oxide matrices because of their attractive electrical and optical properties which are suitable for different applications like photo-detectors 1–3 , solar cells 4 , light-emitting diodes 5 , memory devices 6 , MOSFET transistors 7,8 and lithium-ion batteries with high charge-discharge rate 9,10 . This effort has the main aim to extend the sensitivity domain of photodetectors toward near infrared (NIR) and therefore to develop the optoelectronics in this wavelength range as Si based photodetectors are usually limited to 1.1–1.2 μ m. Ge is the main candidate that has attracted attention for Si replacement because Ge has a higher carrier mobility than Si 11 .…”

Low-Temperature Induced Enhancement of Photoelectric Performance in Semiconducting Nanomaterials

“…Huang et al reported the phenomenon that black-phosphorus-based photodetectors show a high responsivity of 7 × 10 6 A W −1 at 900 nm laser with an intensity of 5 mW cm −2 [ 78 ], exceeding the detection limit at room temperature. Another research on Ge QDs photodetectors observes an extraordinary and obvious photoresponse to near-IR light with only 10 nW of light intensity [ 135 ]. The enhanced weak light response is likely due to the integrating function of suppressed noise current and enhanced absorption.…”

Integrated Photodetectors Based on Group IV and Colloidal Semiconductors: Current State of Affairs

“…In 2018, a PDs based on Ge QDs fabricated on Ge substrates has been demonstrated with a broadband photoresponse spectral range (λ = 400–1550 nm) [ 70 ]. Its responsivity at room temperature was up to 1.12 A/W, the obtained internal quantum efficiency was IQE = 313%, higher than conventional Si and Ge photodiodes, specific detectivity at room-temperature was D* ≈ 210 10 cm Hz 1/2 W −1 both at visible λ = 640 nm and telecom λ = 1550 nm wavelengths.…”

“…Its responsivity at room temperature was up to 1.12 A/W, the obtained internal quantum efficiency was IQE = 313%, higher than conventional Si and Ge photodiodes, specific detectivity at room-temperature was D* ≈ 210 10 cm Hz 1/2 W −1 both at visible λ = 640 nm and telecom λ = 1550 nm wavelengths. When the operating temperature and incident power were decreased, sharply improved performance were obtained, indeed at T = 100K for an incident power of 10 nW at λ = 1550 nm, the device showed D* = 1.110 12 cm Hz 1/2 W −1 and IQE = 1000% [ 70 ].…”