2018年11月27日星期二

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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2018年11月12日星期一

Study of annealed InAs/GaAs quantum dot structures



Two similar samples of InAs or GaAs quantum dots and their response to annealing at 700°C have been studied using scanning transmission electron microscopy. The only difference in the growth of both samples is the inclusion of p-doping by carbon in the GaAs barriers between the quantum dots in one of the wafers. The size and line density of and the change of indium concentration within the quantum dots have been investigated to understand the effect of carbon doping on the diffusion of indium atoms within the structures during the anneal.




Source:IOPscience

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