Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userGaAs/AlGaAs Nanowire Photodetector
500
0
0.0
(
0
)
Added by
Christophe Couteau Asst Prof
Publication date
2016
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We demonstrate an efficient core-shell GaAs/AlGaAs nanowire photodetector operating at room temperature. The design of this nanoscale detector is based on a type-I heterostructure combined with a metal-semiconductor-metal (MSM) radial architecture, in which built-in electric fields at the semiconductor heterointerface and at the metal/semiconductor Schottky contact promote photogenerated charge separation, enhancing photosensitivity. The spectral photoconductive response shows that the nanowire supports resonant optical modes in the near-infrared region, which lead to large photocurrent density in agreement with the predictions of electromagnetic and transport computational models. The single nanowire photodetector shows remarkable peak photoresponsivity of 0.57 A/W, comparable to large-area planar GaAs photodetectors on the market, and a high detectivity of 7.2 10^10 cmsqrt{Hz}/W at {lambda}=855 nm. This is promising for the design of a new generation of highly sensitive single nanowire photodetectors by controlling optical mode confinement, bandgap, density of states, and electrode engineering.
rate research
Read More
Enhanced photocurrent is demonstrated in a junction-less photodetector with nanowires embedded in its channel. The fabricated photodetector consists of a large area for efficient absorption of incident light with energy band engineering achieved in nanowires. The structure design consists of a set of two symmetrically positioned gates, primary and secondary, that are located over the nanowires. Each gate is used for biasing and control of the charge flow. We find that detectors with narrower nanowires controlled by their secondary gate generate larger photocurrents under similar illumination conditions. Our results show that while the dark current remains the same, the photocurrent increases as the nanowire width decreases.
We have fabricated quantum dot single electron transistors, based on AlGaAs/GaAs heterojunctions without modulation doping, which exhibit clear and stable Coulomb blockade oscillations. The temperature dependence of the Coulomb blockade peak lineshape is well described by standard Coulomb blockade theory in the quantum regime. Bias spectroscopy measurements have allowed us to directly extract the charging energy, and showed clear evidence of excited state transport, confirming that individual quantum states in the dot can be resolved.
Slow magnetooscilations of the conductivity are observed in a 75 nm wide quantum well at heating of the two-dimensional electrons by a high-intensity surface acoustic wave. These magnetooscillations are caused by intersubband elastic scattering between the symmetric and asymmetric subbands formed due to an electrostatic barrier in the center of the quantum well. The tunneling splitting between these subbands as well as the intersubband scattering rate are determined.
We report on quantum Hall stripes (QHSs) formed in higher Landau levels of GaAs/AlGaAs quantum wells with high carrier density ($n_e > 4 times 10^{11}$ cm$^{-2}$) which is expected to favor QHS orientation along unconventional $left < 1bar{1}0 right >$ crystal axis and along the in-plane magnetic field $B_{||}$. Surprisingly, we find that at $B_{||} = 0$ QHSs in our samples are aligned along $left < 110 right >$ direction and can be reoriented only perpendicular to $B_{||}$. These findings suggest that high density alone is not a decisive factor for either abnormal native QHS orientation or alignment with respect to $B_{||}$, while quantum confinement of the 2DEG likely plays an important role.
We study phonon emission in a GaAs/AlGaAs double quantum dot by monitoring the tunneling of a single electron between the two dots. We prepare the system such that a known amount of energy is emitted in the transition process. The energy is converted into lattice vibrations and the resulting tunneling rate depends strongly on the phonon scattering and its effective phonon spectral density. We are able to fit the measured transition rates and see imprints of interference of phonons with themselves causing oscillations in the transition rates.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
