Optical characterization of InAs film grown on SnO2substrate by the electrodeposition technique

Indium arsenide films have been grown by an electrodeposition process at low temperature on a tin oxide (SnO2) substrate. X-ray diffraction studies showed that the as-grown films are poorly crystallized and heat treatment improved the crystallinity of InAs films. Atomic force microscopic measurements revealed that the InAs film surface is formed by particles for which the grain size depends on the electrolysis parameters; we have found that the grain size increases with the electrolysis current density. Absorption measurements show that the band gap energy red-shifts with increasing particle size. This result can be interpreted as a consequence of the quantum confinement effect on the carriers in the nanocrystallites.

Source:IOPscience

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Growth of InAs on micro- and nano-scale patterned GaAs(001) substrates by molecular beam epitaxy

Molecular beam epitaxy of InAs on micro- and nano-scale patterned GaAs(001) substrates was studied. An InAs epilayer grown on the micro-scale patterned substrate exhibits islands with {1 1 3}-type facets, and is similar to that grown on the flat (unpatterned) substrate. In contrast, the preferred growth of InAs on the nano-scale patterned substrate is in the \langle 001\rangle  direction and exhibits islands with {1 1 0}-type facets. The thickness of the dense dislocation networks at the interface due to strain relaxation is reduced by the micro-scale pattern in comparison with the flat substrate, while for growth on the nano-scale patterned substrate, the strain relaxes via the formation of stacking faults more than dislocations. X-ray diffraction reveals that the strains in the 300 nm InAs epilayers are nearly fully relaxed, and the patterns tend to decrease the lattice constants of the epilayer, implying mass transport of Ga atoms into the epilayer from the GaAs substrates.

Source:IOPscience

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Estimation of doping density in low doped n-InAs by electrolyte-based capacitance-voltage measurements in the deep depletion mode

Doping density profiling in InAs is difficult due to lack of good quality Schottky contacts and the narrow bandgap nature of the material. The electrolyte can be used to form a Schottky-like contact but the inversion layer formation does not allow obtaining a dopant concentration in low doped InAs. To overcome this issue, a pulse CV technique has been implemented to drive a sample into the deep depletion mode which makes it possible to use the depletion approximation to calculate a carrier concentration. The measured capacitance-voltage characteristics were compared with the simulation and showed good agreement with it.

Source:IOPscience

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Photoluminescence study of low density InAs quantum clusters grown by molecular beam epitaxy

We report a systematic optical spectroscopy study of low density InAs quantum clusters (QCs) grown by molecular beam epitaxy. The photoluminescence (PL) spectra show emission features of a wetting layer (WL) which contains hybridized quantum well states. The low-energy tail of the QCs' PL profile is actually an ensemble of some sharp lines, originating from the emission of different exciton states (e.g. X, X*, XX*) in a single quasi-three-dimensional (Q3D) cluster as detailed in the micro-PL spectra. The temperature dependence of PL spectra indicates photocarrier distribution and transport in the QC–WL system. Furthermore, this small InAs Q3D cluster is integrated with a distributed Bragg reflector structure, and using optical excitation creates a single photon source with the second-order correlation function of g(2)(0) = 0.31 at 16 K.

Source:IOPscience

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