In this paper questions of optimization of growth conditions in the method of molecular beam epitaxy for creation of high-efficient quantum dot infrared photodetectors are considered. As a model material system for theoretical investigations, heterostructures with germanium-silicon quantum dots on the silicon surface are chosen. For calculations of the dependencies of quantum dots array parameters on synthesis conditions the kinetic model of growth of differently shaped quantum dots based on the general nucleation theory is proposed. The theory is improved by taking into account the change in free energy of nucleation of an island due to the formation of additional edges of islands and due to the dependence of surface energies of facets of quantum dots on the thickness of a 2D wetting layer during the Stranski–Krastanow growth. Calculations of noise and signal characteristics of infrared photodetectors based on heterostructures with quantum dots of germanium on silicon are done. Dark current in such structures caused by thermal emission and barrier tunneling of carriers, as well as detectivity of the photodetector in the approximation of limitation by generation-recombination noises are estimated. Moreover, the presence of dispersion of quantum dots by size is taken into account in the calculations of the generation-recombination noises. Results of calculations of the properties of structures with quantum dots and their dependencies on growth parameters, as well as the characteristics of quantum dot photodetectors are presented. Comparison of the estimated parameters of quantum dots ensembles and the characteristics of quantum dot photodetectors with experimental data is carried out.

A theoretical analysis of the mid-wavelength infrared range detectors based on the HgCdTe materials for high operating temperatures is presented. Numerical calculations were compared with the experimental data for HgCdTe heterostructures grown by the MOCVD on the GaAs substrates. Theoretical modelling was performed by the commercial platform SimuAPSYS (Crosslight). SimuAPSYS fully supports numerical simulations and helps understand the mechanisms occurring in the detector structures. Theoretical estimates were compared with the dark current density experimental data at the selected characteristic temperatures: 230 K and 300 K. The proper agreement between theoretical and experimental data was reached by changing Auger-1 and Auger-7 recombination rates and Shockley-Read-Hall carrier lifetime. The level of the match was confirmed by a theoretical evaluation of the current responsivity and zero-bias dynamic resistance area product (R0A) of the tested detectors.

In this paper, a low power highly sensitive Triple Metal Surrounding Gate (TM-SG) Nanowire MOSFET photosensor is proposed which uses triple metal gates for controlling short channel effects and III–V compound as the channel material for effective photonic absorption. Most of the conventional FET based photosensors that are available use threshold voltage as the parameter for sensitivity comparison but in this proposed sensor on being exposed to light there is a substantial increase in conductance of the GaAs channel underneath and, thereby change in the subthreshold current under exposure is used as a sensitivity parameter (i.e., I_illumination/I_Dark). In order to further enhance the device performance it is coated with a shell of Al_xGa_1-xAs which effectively passivates the GaAs surface and provides a better carrier confinement at the interface results in an increased photoabsorption. At last performance parameters of TM-SG Bare GaAs Nanowire MOSFET are compared with TM-SG core-shell GaAs/AlGaAs Nanowire MOSFET and the results show that Core-Shell structures can be a better choice for photodetection in visible region.

Dual-band infrared detector, which acquires more image information than single-band detectors, has excellent detection, recognition, and identification capabilities. The dual-band detector can have two bumps to connect with each absorber layer, but it is difficult to implement small pitch focal plane arrays and its fabrication process is complicated. Therefore, the most effective way for a dual-band detector is to acquire each band by bias-selectable with one bump. To aim this, a dual-band MWIR/LWIR detector based on an InAs/GaSb type-II superlattice nBn structure was designed and its performance was evaluated in this work. Since two absorber layers were separated by the barrier layer, each band can be detected by bias-selectable with one bump. The fabricated dual-band device exhibited the dark current and spectral response characteristics of MWIR and LWIR bands under negative and positive bias, respectively. Spectral crosstalk that is a major issue in dual-band detectors was also improved. Finally, a 20 μm pitch 640 × 512 dual-band detector was fabricated, and both MWIR and LWIR images exhibited an average noise equivalent temperature difference of 30 mK or less at 80 K.

The hyperspectral thermal imaging instrument for technology demonstration funded by NASA’s Earth Science Technology Office under the In-Space Validation of Earth Science Technologies program requires focal plane array with reasonably good performance at a low cost. The instrument is designed to fit in a 6U CubeSat platform for a low-Earth orbit. It will collect data on hydrological parameters and Earth surface temperature for agricultural remote sensing. The long wavelength infrared type-II strain layer superlattices barrier infrared detector focal plane array is chosen for this mission. With the driving requirement dictated by the power consumption of the cryocooler and signal-noise-ratio, cut-off wavelengths and dark current are utilized to model instrument operating temperature. Many focal plane arrays are fabricated and characterised, and the best performing focal plane array that fulfils the requirements is selected. The spectral band, dark current and 8–9.4 m pass band quantum efficiency of the candidate focal plane array are: 8–10.7 m, 2.1∙10−5 A/cm2, and 47%, respectively. The corresponding noise equivalent difference temperature and operability are 30 mK and 99.7%, respectively. Anti-reflective coating is deposited on the focal plane array surface to enhance the quantum efficiency and to reduce the interference pattern due to an absorption layer parallel surfaces cladding material.