The bulk of InSb and GaSb crystals grown by VDS have been used for infrared applications. Crystal performance needs to be improved for sensors and detectors.
Modern solid state electronics makes extremely high demands on the quality of semiconductor materials used, primarily, to their purity, homogeneity and structural perfection. A necessary condition for achieving high performance electro-semiconductor materials is their deep cleaning from impurities. In the narrow-gap semiconductor materials for infrared imaging intrinsic point defects strongly affect the concentration and mobility of charge carriers, i.e., exhibit a high electrical activity. This, in turn, alters the spread parameters of the devices based on them (noise threshold and sensitivity, etc.). On the parameters of modern devices affect not only the presence of dopants and genetic defects, but even their uneven distribution in the crystal volume.
Semiconductor materials are characterized by the following main electrophysical parameters: resistivity, conductivity type, a band gap, carrier concentration and mobility, effective mass and lifetime. Several characteristics of semiconductor materials, e.g., band-gap and the effective mass of carriers is relatively weakly dependent on the concentration of chemical additives and the degree of perfection of the crystal lattice. However, most of the parameters are structurally sensitive, and in semiconductor materials, a dramatic dependence of the properties, primarily electrophysical, not only on the content of impurities, but also on the degree of perfection of the crystal structure. Point defects, both in-house and dopants, the concentration, the conductivity type, the value of resistivity. Doping of semiconductor materials is carried out in order to obtain crystals with the desired properties. Defined properties vary within very wide limits and, as a rule, it is necessary to grow crystals with a certain combination of different properties (e.g., optical and electrical), with the high homogeneity of the distribution of the latter in volume.
The pattern of distribution of dislocations and their density are limited due to the negative influence of dislocations on the many characteristics of semiconductor devices. Point defects , dislocations , stacking faults , and other violations of the structure is controlled by diffusion processes in the material. Structural defects have a significant impact on the performance and operational reliability of semiconductor devices. In this regard, to perfection structure of semiconductors are presented exceptionally high demands. In most cases, the task of growing crystals for producing crystals with a high degree of structural perfection is set.
Hello Dattatray,
Infrared semiconductor devices, due to the relatively low frequency range of their operation, are more prone to noise from the lattice vibrational frequencies. This is why, compared to their higher band gap counterparts, better crystalline quality is required of the low band gap semiconductors like InSb and GaSb. This is true not just for detectors, but for emitting devices as well. Electronic states introduced in the band gap by defects are very efficient radiation 'killers'.
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