Interband Photoconductivity of Metamorphic InAs/InGaAs Quantum Dots in the 1.3–1.55-μm Window

Abstract

Photoelectric properties of the metamorphic InAs/InxGa1 − xAs quantum dot (QD) nanostructures were studied at room temperature, employing photoconductivity (PC) and photoluminescence spectroscopies, electrical measurements, and theoretical modeling. Four samples with different stoichiometry of InxGa1 − xAs cladding layer have been grown: indium content x was 0.15, 0.24, 0.28, and 0.31. InAs/In0.15Ga0.85As QD structure was found to be photosensitive in the telecom range at 1.3 μm. As x increases, a redshift was observed for all the samples, the structure with x = 0.31 was found to be sensitive near 1.55 μm, i.e., at the third telecommunication window. Simultaneously, only a slight decrease in the QD PC was recorded for increasing x, thus confirming a good photoresponse comparable with the one of In0.15Ga0.75As structures and of GaAs-based QD nanostructures. Also, the PC reduction correlate with the similar reduction of photoluminescence intensity. By simulating theoretically the quantum energy system and carrier localization in QDs, we gained insight into the PC mechanism and were able to suggest reasons for the photocurrent reduction, by associating them with peculiar behavior of defects in such a type of structures. All this implies that metamorphic QDs with a high x are valid structures for optoelectronic infrared light-sensitive devices.

Defect influence on in-plane photocurrent of InAs/InGaAs quantum dot array: long-term electron trapping and Coulomb screening

“…For the in-plane photoelectric measurements, two contacts of InGa eutectic were applied to the surface of the samples. Ohmicity of the contacts was verified [36]. Standard direct current detection was used for the PC studies: the current under bias of 32 V was measured by a multimeter as a voltage drop across a series load resistance [43,44].…”

“…Standard direct current detection was used for the PC studies: the current under bias of 32 V was measured by a multimeter as a voltage drop across a series load resistance [43,44]. The details of sample connection and electrical measurements can be found elsewhere [36]. PC was excited by a 250 W halogen lamp light dispersed with a prism monochromator, and PC spectra were recorded at room temperature (300 K) and 77 K. The spectra were normalized to the excitation quanta number of the light source.…”

“…The InAs QD was considered as having a truncated conical shape and size taken from experimental AFM data [27]. Details and theoretical background of the calculation are given in [36,50].…”

“…Owing to these peculiar properties, such nanostructures have found successful applications in the design and fabrication of infrared (IR) photonic and light-sensitive devices, such as QD lasers [28,29], single-photon emitters [30][31][32], and solar cells [33][34][35]. Very recently, we have shown that normal incident light at 1.3-1.55 μm is absorbed by metamorphic QD structures, based on photocurrent (PC) measurements [36]. Also, significant efforts in optimizing the structure design were carried on to avoid the influence on PC of the substrate and of nearby layers with interface defects [37].…”

Optical windows for head tissues in near‐infrared and short‐wave infrared regions: Approaching transcranial light applications

“…Being encouraged by a rapid progress in the development of new NIR‐SWIR sensitive cameras based on InGaAs or InSb photodetectors and new laser sources , the use of NIR‐SWIR light for in vivo applications (ie, optical imaging and therapy) are being actively advanced. These windows allow researchers to benefit from the reduced tissue scattering and autofluorescence in these spectral regions and achieve deeper light penetration .…”