2019年8月22日星期四

High performance InAs/GaAsSb superlattice long wavelength infrared photo-detectors grown on InAs substrates

We demonstrated high performance long wavelength InAs/GaAs0.09Sb0.91 type-II superlattices infrared photo-detectors grown on InAs substrates. Superlattices photodiodes with InAs layer thickness from 14 to 24 ML showed 50% cutoff wavelength from 6 to 12.5 μm while the lattice-mismatch was kept smaller than 4.0 × 10−4 without any additional interface layers for strain balance. Quantum efficiency spectra showed oscillating characteristics which were attributed to the plasma effect in the highly doped InAs buffer layers. The absorption coefficient of 1800 cm−1 and diffusion length of 10 μm of minority carriers in the SLs on InAs have been obtained through simulation. A photodiode exhibited a 12.5 μm cutoff wavelength with a peak detectivity of 7.4 × 1010 cm Hz1/2 W−1 and 2.6 × 1011 cm Hz1/2 W−1 at 76 K and 52 K, respectively.


Source:IOPscience

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2019年8月9日星期五

Free-Standing InAs/InGaAs Microtubes and Microspirals on InAs (100)

A new material system for creating InAs-based free-standing micro- and nanoobjects is proposed. For the first time, InAs/InGaAs microtubes and microspirals were obtained, including tubes containing two-dimensional electron gas, ordered arrays of tubes, and tubes protruding over the substrate edge. First measurements of the electrical conductivity of InAs/InGaAs microtubes were performed.



Source:IOPscience


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2019年8月1日星期四

Growth and characterization of InAs layers obtained by liquid phase epitaxy from Bi solvents

In this paper, we report the first liquid phase epitaxial growth of InAs epitaxial layers using 100% Bi solvent. At a growth temperature of 470 °C, the layers are macroscopically mirror like and the obtained growth rate is ~40 nm min−1. High-resolution XRD measurements reveal perfect lattice matching between the layer and the substrate, very good structural quality of the layers and less than 0.07% content of substitutional Bi in the layer. Raman spectra from background-doped layers are indicative of carrier concentration near the epilayer surface of less than 1016 cm−3, while assessment of these layers by means of infrared reflectance spectroscopy points to carrier concentration in the bulk of the layers of the order of 1 × 1015 cm−3. 4 K photoluminescence spectra from the same layers exhibit excitonic lines with half-widths 3 meV, which is a signature for electron concentration comparable to the known critical Mott density in InAs of ~5 × 1014 cm−3. We attribute the low background doping of the epitaxial layers to the low dissolution in Bi of Si and other residual impurities at 470 °C.



Source:IOPscience

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