A5026115376- Photonic and Optical Devices
- Nanowire Synthesis and Applications
- Semiconductor materials and devices
- Advanced Photonic Communication Systems
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor Lasers and Optical Devices
- Thin-Film Transistor Technologies
- Semiconductor materials and interfaces
- Photonic Crystals and Applications
- Neural Networks and Reservoir Computing
- ZnO doping and properties
- Ga2O3 and related materials
- Semiconductor Quantum Structures and Devices
- Electronic and Structural Properties of Oxides
- Advanced Fiber Optic Sensors
- Integrated Circuits and Semiconductor Failure Analysis
- Optical Coatings and Gratings
- Ferroelectric and Negative Capacitance Devices
- GaN-based semiconductor devices and materials
- Photonic Crystal and Fiber Optics
- Mechanical and Optical Resonators
- Phase-change materials and chalcogenides
- Advanced Optical Sensing Technologies
- Acoustic Wave Resonator Technologies
- MXene and MAX Phase Materials
University College London
2024
National University of Singapore
2014-2020
Singapore-MIT Alliance for Research and Technology
2016
Nanyang Technological University
2016
We report on the demonstration of photodetectors based large scale two-dimensional molybdenum disulfide (MoS2) transition metal dichalcogenides. Excellent film uniformity and precise control MoS2 thickness down to a monolayer (~0.75nm) were achieved by magnetron sputtering synthesis approach. In particular, integrated with five monolayers exhibit high photoresponsivity 1.8 A/W, an external quantum efficiency exceeding 260%, photodetectivity ~5 x 10(8) Jones for wavelength 850 nm, surpassing...
We report the demonstration of a germanium-tin (Ge0.9Sn0.1) multiple-quantum-well p-i-n photodiode on silicon (Si) substrate for 2 μm-wavelength light detection. Characterization photodetector in both direct current (DC) and radio frequency (RF) regimes was performed. At bias voltage -1 V, dark density 0.031 A/cm2 is realized at room-temperature, which among lowest reported values Ge1-xSnx-on-Si photodiodes. In addition, first time, 3 dB bandwidth (f3dB) around 1.2 GHz achieved Ge1-xSnx...
We demonstrate that a complementary metal-oxide-semiconductor (CMOS) compatible silicon (Si) surface passivation technique effectively suppress the dark current originating from mesa sidewall of Ge(0.95)Sn(0.05) on Si (Ge(0.95)Sn(0.05)/Si) p-i-n photodiode. Current-voltage (I-V) characteristics show could reduce leakage density (Jsurf) photodiode by ~100 times. A low (Jdark) 0.073 A/cm(2) at bias voltage -1 V is achieved, which among lowest reported values for Ge(1-x)Sn(x)/Si photodiodes....
We report the demonstration of a Ge <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.95</sub> Sn xmlns:xlink="http://www.w3.org/1999/xlink">0.05</sub> on silicon (Ge /Si) avalanche photodiode (APD) having separate-absorption-charge-multiplication structure, wherein layer and Si function as an absorption multiplication layer, respectively. Material characterization was performed by atomic force microscopy, X-ray diffraction, transmission...
The floating-base germanium-tin (Ge1-xSnx) heterojunction phototransistor (HPT) is designed and investigated as an efficient optical receiver in the short-wave infrared range. Simulations indicate that Sn content increases, responsivity significantly increases due to a higher absorption coefficient larger valence band offset between Ge Ge1-xSnx. Ge0.935Sn0.065 HPTs incorporated high-quality film grown by molecular beam epitaxy were fabricated, demonstrating response beyond wavelength of 2003...
We report the first experimental demonstration of germanium-tin (GeSn) lateral p-i-n photodetector on a novel GeSn-on-insulator (GeSnOI) substrate. The GeSnOI is formed by direct wafer bonding and layer transfer technique, which promising for large-scale integration nano-electronics photonics devices. fabricated shows well-behaved diode characteristics with high Ion/Ioff ratio ~4 orders magnitude (at ± 1 V) at room temperature. A cutoff detection beyond 2 µm photo responsivity (Rop) 0.016...
High-performance GeSn multiple-quantum-well (MQW) photodiode is demonstrated on a 200 mm Ge-on-insulator (GeOI) photonics platform for the first time. Both MQW active layer stack and Ge (top of GeOI after bonding) were grown using single epitaxy step standard (001)-oriented Si substrate (donor wafer) reduced pressure chemical vapor deposition (RPCVD). Direct wafer bonding transfer technique then employed to device layers SiO2-terminated handle substrate. The surface illuminated realized this...
We report the first demonstration of high-performance GeSn metal-semiconductormetal (MSM) photodetector and p-type fin field-effect transistor (pFinFET) on an advanced GeSn-on-insulator (GeSnOI) platform by complementary metal-oxidesemiconductor (CMOS) compatible processes.The detection range is extended beyond 2 µm, with responsivities 0.39 0.10 A/W at 1550 nm 2003 nm, respectively.Through insertion ultrathin Al O 3 Schottky-barrier-enhancement layer, dark current I Dark suppressed more...
GeSn-on-insulator (GeSnOI) on Silicon (Si) substrate was realized using direct wafer bonding technique. This process involves the growth of Ge1-xSnx layer a first Si (001) (donor wafer) followed by deposition SiO2 Ge1-xSnx, donor to second (handle wafer), and removal wafer. The GeSnOI material quality is investigated high-resolution transmission electron microscopy, X-ray diffraction (HRXRD), atomic-force Raman spectroscopy, spectroscopic ellipsometry. has surface roughness 1.90 nm, which...
The effect of room temperature sulfur passivation the surface Ge0.83Sn0.17 prior to high-k dielectric (HfO2) deposition is investigated. X-ray photoelectron spectroscopy (XPS) was used examine chemical bonding at interface HfO2 and Ge0.83Sn0.17. Sulfur found be effective in suppressing formation both Ge oxides Sn oxides. A comparison XPS results for sulfur-passivated non-passivated samples shows that GeSn could also suppress segregation atoms. In addition, reduces trap density Dit...
Germanium–tin (GeSn) p-channel fin field-effect transistor (p-FinFET) was realized on a novel GeSn-on-insulator (GeSnOI) substrate. The high-quality GeSnOI substrate formed using direct wafer bonding technique and layer-transferred from 300-mm GeSn/Ge/Si donor wafer. Material quality examined atomic force microscopy, high-resolution transmission electron Raman spectroscopy, X-ray diffraction. fabricated GeSn p-FinFETs exhibit small subthreshold swing ( <inline-formula...
We report the demonstration of a germanium-tin multiple quantum well (Ge0.9Sn0.1 MQW)-on-Si avalanche photodiode (APD) for light detection near 2 μm wavelength range. The measured spectral response covers wavelengths from 1510 to 2003 nm. An optical responsivity 0.33 A W−1 is achieved at nm due internal gain. In addition, thermal coefficient breakdown voltage extracted be 0.053% K−1 based on temperature-dependent dark current measurement. As compared traditional APDs, Si-based APD promising...
The world's first GeSn p-FinFETs formed on a novel GeSn-on-insulator (GeSnOI) substrate is reported, with channel lengths L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ch</sub> down to 50 nm and fin width W xmlns:xlink="http://www.w3.org/1999/xlink">Fin</sub> 20 nm. In comparison other reported p-FETs, record low S of 79 mV/decade, high G xmlns:xlink="http://www.w3.org/1999/xlink">m, int</sub> , 807 μS/um (VDs -0.5 V), the highest /S...
A heavily Ga-doped Ge0.95Sn0.05 layer was grown on the Ge (100) substrate by molecular beam epitaxy (MBE), achieving an active doping concentration of 1.6 × 1020 cm−3 without use ion implantation and high temperature annealing that could cause Sn precipitation or surface segregation. An advanced nano-scale transfer length method used to extract specific contact resistivity ρc between metal doped p-Ge0.95Sn0.05 layer. By incorporating into in-situ Ga during MBE growth, ultra-low 1.4 10−9...
We propose and demonstrate Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> metal-oxide-semiconductor field-effect transistors (MOSFETs) on a high thermal conductivity AlN/Si substrate to improve the heat dissipation capability keep their cost-effectiveness. Owing optimized source/drain contact Al /Ga interface, drain current of 580 mA/mm peak intrinsic transconductance G...
We developed a new digital etch process that allows precise etching of Germanium or Germanium-tin (Ge1-x Sn x ) materials. The approach consists Ge1-x oxide formation by plasma oxidation and removal in diluted hydrochloric acid at room temperature. first step is self-limiting process, as the thickness layer grows logarithmically with time saturates fast. Consistent rates each cycle were found on samples, surfaces remaining smooth after etch. parameters tuned to achieve various rates. By...
Ga and Sn surface-segregated GeSn (Seg. p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -GeSn) layer with an average active doping concentration of 3.4 x 10 xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> surface composition N7% was grown on the Ge (100) substrate by molecular beam epitaxy. An ultralow specific contact resistivity ρ <sub...
InAlP-capped Ge nFETs with sub-400 °C process modules were reported. on substrates InAlP/Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /HfO as gate dielectrics demonstrate the highest reported (100) peak μ xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> for inversion mode devices. In addition, stack HfO directly deposited InAlP cap was implemented in 300 mm Si first time....
High temperature performance of Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) was investigated at temperatures 25 °C–300 °C. A 30.7% on-state current reduction observed when the increased from °C to 300 On-state and peak intrinsic transconductance decreased increases followed a power law, indicating that high electron mobility is limited by phonon scattering. Threshold voltage also shift positively with an increase rate ∼2.3 mV °C−1 increased. In terms off-state...
We investigate the thermal stability of germanium-tin (Ge1−xSnx) fins under rapid annealing in N2 ambient. The Ge1−xSnx were formed on a GeSn-on-insulator substrate and found to be less thermally stable than blanket films. morphology change material quality annealed fin are investigated using scanning electron microscopy, Raman spectroscopy, high-resolution transmission energy-dispersive X-ray energy loss spectroscopy. Obvious degradation crystalline Ge0.96Sn0.04 was observed, thin Ge layer...
To enable heterogeneous integration of InGaAs based transistors with Si complementary metal–oxide–semiconductor (CMOS) devices, metal contacts to n+-InGaAs need have high thermal stability for CMOS process compatibility and ultra-low contact resistance achieve good device performance. In this work, resistivity ρc on refractory metals such as molybdenum (Mo) were realized. Use achieves stability. An improved that eliminates oxide between the by using an in situ Ar+-plasma treatment prior...
Record-low specific contact resistivity ρ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> down to 1.2×10 <sup xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> Ω-cm xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved for Ti/p xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -Ge xmlns:xlink="http://www.w3.org/1999/xlink">0.95</sub> Sn xmlns:xlink="http://www.w3.org/1999/xlink">0.05</sub> by incorporating into Ge and insitu...
Strain relaxation of biaxially strained Ge1-xSnx layer when it is patterned into fin structures studied. Ge1-xSnx-on-insulator (GeSnOI) substrate was realized using a direct wafer bonding (DWB) technique and were formed by electron beam lithography (EBL) patterning dry etching. The strain in the fins having widths (WFin) ranging from 1 μm down to 80 nm characterized micro-Raman spectroscopy. Raman measurements show that increases with decreasing WFin. Finite element (FE) simulation shows...
Ga and Sn surface-segregated p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -GeSn (Seg. -GeSn) was grown by molecular beam epitaxy (MBE) to achieve an average active doping concentration of 3.4×10 xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> surface composition more than 8%. This enables the realization record-low specific contact resistivity ρ <sub...
We realized the first germanium-tin (GeSn) gate-alI-around (GAA) p-channel field-effect-transistors (p-FETs) on a 200 mm GeSn-on-insulator (GeSnOI) substrate, achieving subthreshold swing (SS) of 74 mV/ decade for device with channel length (LCH) 60 nm. The GAA structure provided excellent control short effects and also enabled realization transistor LCH 20 nm decent electrical characteristics.