Daosheng Li

Dry Etched Waveguide Laser Diode on GeOI

We demonstrate a top-top contact, dry etched mirror facet III-V waveguide laser diode grown on germanium-on-insulator (GeOI). A 3 × InGaAs/GaAs quantum well designed to lase at 985 nm was grown on a GaAs buffer, which was lattice matched to the GeOI platform in order to realize the monolithic integration of III-V electronic and photonic devices with silicon and SiO2. Lasing occurred at ~ 985 nm with a threshold current density of ~ 2 kA/cm2. Pulsed measurements, and SEM and TEM characterization methods were used. The issue of heat transfer limited the performance of the laser.

GaInNAs double-barrier quantum well infrared photodetector with the photodetection at 1.24μm

A GaInNAs∕AlAs∕AlGaAs double-barrier quantum well infrared photodetector was grown by molecular beam epitaxy and fabricated by standard device processes. The growth structure of the as-grown sample was verified by x-ray diffraction measurement. The photoluminescence emission peak, which is related to the interband transition in the GaInNAs well, was observed at ∼1.2eV. After annealing at 650°C, a large blueshift of 40meV was observed. The photocurrent peak at 1.24μm is associated with the intersubband transitions in the conduction band of the GaInNAs quantum well. The ten-band k∙p calculations agree with the above observations.

Study of a 1 eV GaNAsSb photovoltaic cell grown on a silicon substrate

We report the performance of a 1 eV GaNAsSb photovoltaic cell grown on a Si substrate with a SiGe graded buffer grown using molecular beam epitaxy. For comparison, the performance of a similar 1 eV GaN0.018As0.897Sb0.085 photovoltaic cell grown on a GaAs substrate was also reported. Both devices were in situ annealed at 700 °C for 5 min, and a significant performance improvement over our previous result was observed. The device on the GaAs substrate showed a low open circuit voltage (VOC) of 0.42 V and a short circuit current density (JSC) of 23.4 mA/cm2 while the device on the Si substrate showed a VOC of 0.39 V and a JSC of 21.3 mA/cm2. Both devices delivered a quantum efficiency of 50%–55% without any anti-reflection coating.

Low temperature grown GaNAsSb: A promising material for photoconductive switch application

We report a photoconductive switch using low temperature grown GaNAsSb as the active material. The GaNAsSb layer was grown at 200 °C by molecular beam epitaxy in conjunction with a radio frequency plasma-assisted nitrogen source and a valved antimony cracker source. The low temperature growth of the GaNAsSb layer increased the dark resistivity of the switch and shortened the carrier lifetime. The switch exhibited a dark resistivity of 107 Ω cm, a photo-absorption of up to 2.1 μm, and a carrier lifetime of ∼1.3 ps. These results strongly support the suitability of low temperature grown GaNAsSb in the photoconductive switch application.

P 2 S 5 /(NH 4 ) 2 S x -Based Sulfur Monolayer Doping for Source/Drain Extensions in n-Channel InGaAs FETs

Ultrashallow junctions that are abrupt and have low resistance are needed for the source/drain extensions (SDEs) of MOSFETs at future technology nodes. In addition, the use of 3-D devices, such as FinFETs or nanowire FETs, will require a doping process that is conformal. In this paper, we discuss P2S5/(NH4)2Sx-based doping for potential use in the formation of SDEs for n-channel InGaAs FETs. MOSFETs with source and drain formed using this doping technique are demonstrated. The effect of the dopant activation step on device performance is also studied.

Infrared spectroscopic ellipsometry study of sulfur-doped In0.53Ga0.47As ultra-shallow junctions

Sulfur mono-layer doped In0.53Ga0.47As films were investigated by infrared spectroscopic ellipsometry. The complex dielectric function of doped layers shows free carrier response which can be described by a single Drude oscillator. Electrical resistivities, carrier relaxation times, and active carrier depths are obtained for the shallow n-In0.53Ga0.47As films. Our results indicate that sub-10 nm sulfur-doped layers with active carrier concentration as high as 1.7 × 1019 cm−3 were achieved. Sheet resistances estimated from infrared spectroscopic ellipsometry are in good agreement with those obtained by electrical methods.

Enabling low power and high speed OEICs: First monolithic integration of InGaAs n-FETs and lasers on Si substrate

We report the first monolithic integration of InGaAs channel transistors with lasers on a Si substrate, achieving a milestone in the direction of enabling low power and high speed opto-electronic integrated circuits (OEICs). The III-V layers for realizing transistors and lasers were grown epitaxially on the Si substrate using MBE. InGaAs n-FETs with Ion/Ioff ratio of more than 106 and very low off-state leakage current were realized. In addition, fabrication process with a low overall processing temperature (≤ 400 °C) was used to realize electrically-pumped GaAs/AlGaAs quantum well (QW) lasers with a lasing wavelength of 795 nm and a linewidth of less than 0.5 nm at room temperature.

Monolithic integration of InGaAs n-FETs and lasers on Ge substrate

We report the first monolithic integration of InGaAs channel field-effect transistors with InGaAs/GaAs multiple quantum wells (MQWs) lasers on a common platform, achieving a milestone in the path of enabling low power and high speed opto-electronic integrated circuits (OEICs). The III-V layers used for realizing transistors and lasers were grown epitaxially on the Ge substrate using molecular beam epitaxy (MBE). A Si-CMOS compatible process was developed to realize InGaAs n-FETs with subthreshold swing SS of 93 mV/decade, ION/IOFF ratio of more than 4 orders of magnitude with very low off-state leakage current, and a peak effective mobility of more than 2000 cm2/V·s. In addition, fabrication process uses a low overall processing temperature (≤ 400 °C) to maintain the high quality of the InGaAs/GaAs MQWs for the laser. Room temperature electrically-pumped lasers with a lasing wavelength of 1.03 µm and a linewidth of less than 1.7 nm were realized.