Ultrafast Multidimensional Spectroscopy with Field Resolution and Noncollinear Geometry at Mid-Infrared Frequencies

Energetic correlations and their dynamics govern the fundamental properties of condensed matter materials. Ultrafast multidimensional spectroscopy in the mid infrared is an advanced technique to study such coherent low-energy dynamics. The intrinsic many-body phenomena in functional solid-state materials, in particular few-layer samples, remain widely unexplored to this date, because complex and weak sample responses demand versatile and sensitive detection. Here, we present a novel setup for ultrafast multidimensional spectroscopy with noncollinear geometry and complete field resolution in the 15-40 THz range. Electric fields up to few-100 kV cm-1 drive coherent dynamics in a perturbative regime, and an advanced modulation scheme allows to detect nonlinear signals down to a few tens of V cm-1 entirely background-free with high sensitivity and full control over the geometric phase-matching conditions. Our system aims at the investigation of correlations and many-body interactions in condensed matter systems at low energy. Benchmark measurements on bulk indium antimonide (InSb) reveal a strong six-wave mixing signal and map ultrafast changes of the band structure with access to amplitude and phase information. Our results pave the way towards the investigation of functional thin film materials and few-layer samples.

Mesa-structures and Focal Plane Arrays based on epitaxially grown InSb layers

Aspects of epitaxially grown indium antimonide (InSb) on InSb substrates (InSb-on-InSb) by molecular beam epitaxy (MBE) for the 2D focal plane arrays fabrication process have been described. The epitaxial growth offers possibility for complex structure production, and then such structures suppose more effective control of the thermal generation charge carriers as the detector temperature is raised above 80 K. Investigations of mid-wave infrared (MWIR) 320256 FPAs with 30 μm pitch and 640512 FPAs with 15 μm pitch based on InSb-on-InSb layers have shown high performance: the average detectivity at T = 77 K more than 21011 cmW-1Hz1/2, the average value of noise equivalent temperature difference (NETD) with a cold aperture of 60o at T = 77K was in the range of 10–20 mK. High quality thermal imaging images were obtained in real time mode.

Synthesis and study of some properties of colloidal quantum dots of indium antimonide

Colloidal quantum dots of indium antimonide have been synthesized by a known technique. The shape and average diameters of quantum dots have been investigated by transmission electron microscopy using a transmission microscope. Controlling the size and shape of colloidal QDs provides information on the formation of the crystal structure of nanoparticles and their possible physical and optical properties. It has been found that InSb quantum dots are characterized by a polygonal shape. The results obtained for QDs correspond to the crystal lattice system of a semiconductor with a cubic crystal lattice structure. Elemental analysis of nanoparticles has been monitored by X-ray microanalysis. The experimental determination error was no more than one percent. The percentages of indium and antimony in QDs according to X-ray microanalysis data corresponded to the theoretical stoichiometry In: Sb = 1:1. Impurities of other elements constituted the level of trace amounts, which confirmed the chemical purity of the synthesized InSb QDs. The fluorescent properties of indium antimonide nanoparticles have been studied. It has been found that the luminescence intensity of InSb nanoparticles at room temperature is insignificant, which is in agreement with the literature data. The quantum yield does not exceed 1%, and the luminescence maximum lies in the range of 1040 nm.

Distribution of sensitivity along the area of FPA pixel, limited by the diffraction limit of the scanning mask

Consideration is given to the distribution of sensitivity along the area of indium antimonide FPA pixel obtained with the aid of the nondestructive method of the scanning mask on the basis of the fast testing open probe installation.

Experimental verification of the field theory of specific heat with the scaling in crystalline matter

The field (geometrical) theory of specific heat is based on the universal thermal sum, a new mathematical tool derived from the evolution equation in the Euclidean four-dimensional spacetime, with the closed time coordinate. This theory made it possible to explain the phenomena of scaling in the heat capacity of condensed matter. The scaling of specific heat of the carbon group elements with a diamond lattice is revisited. The predictions of the scaling characteristics for natural diamond and grey tin are verified with published experimental data. The fourth power in temperature in the quasi-low temperature behaviour of the specific heat of both materials is confirmed. The phenomenon of scaling in the specific heat, previously known only in glassy matter, is demonstrated for some zincblend lattice compounds and diamond lattice elements, with their characteristic temperatures. The nearly identical elastic properties of grey tin and indium antimonide is the cause for similarity of their thermal properties, which makes it possible to make conjectures about thermal properties of grey tin.

Growth of 100 mm indium antimonide single crystals by modified Czochralski technique

Currently there is a worldwide trend to increase the diameter of crystals grown from elemental semiconductors and semiconductor compounds. According to literary data the diameter of 3–5 semiconductor single crystals grown nowadays is 4 to 6 inches. So far up to 75 mm indium antimonide single crystals have been grown in Russia. Indium antimonide is the element base for the widest field of solid state electronics, i.e., optoelectronics. Indium antimonide is used for the fabrication of 3–5 mm range linear photodetectors and photodetector arrays used as light-sensitive material in heat vision systems. Growth heat conditions have been selected and 100 mm [100] indium antimonide single crystals have been grown using the modified two-stage Czochralski technique. The graphite heating unit has been oversized to accommodate a 150 mm crucible and a 4.5–5 kg load. The results of the work have provided for a substantial increase in the yield of photodetectors. The electrophysical properties of the as-grown single crystals have been studied using the Van der Pau method and proved to be in agreement with the standard parameters of undoped indium antimonide. Using the 9-field etch method of pit counting under an optical microscope the dislocation density in the 100 mm single crystals has been measured to be ≤ 100 cm-2which is similar to that for 50 mm single crystals.