Issues of Ge hut array formation and growth at low temperatures on the Ge/Si(001) wetting layer are discussed on the basis of explorations performed by high resolution STM and in-situ RHEED. Data of HRTEM studies of multilayer Ge/Si heterostructures
are presented with the focus on low-temperature formation of perfect films. Heteroepitaxial Si p-i-n-diodes with multilayer stacks of Ge/Si(001) quantum dot dense arrays built in intrinsic domains have been investigated and found to exhibit the photo-emf in a wide spectral range from 0.8 to 5 mcm. An effect of wide-band irradiation by infrared light on the photo-emf spectra has been observed. Photo-emf in different spectral ranges has been found to be differently affected by the wide-band irradiation. A significant increase in photo-emf is observed in the fundamental absorption range under the wide-band irradiation. The observed phenomena are explained in terms of positive and neutral charge states of the quantum dot layers and the Coulomb potential of the quantum dot ensemble. By using a coherent source spectrometer, first measurements of terahertz dynamical conductivity (absorptivity) spectra of Ge/Si(001) heterostructures were performed at frequencies 0.3-1.2 THz in the temperature interval from 300 to 5 K. The effective dynamical conductivity of the heterostructures with Ge quantum dots has been discovered to be significantly higher than that of the structure with the same amount of bulk germanium (not organized in an array of quantum dots). The excess conductivity is not observed in the structures with the Ge coverage less than 8 AA. When a Ge/Si(001) sample is cooled down the conductivity decreases. We discuss possible mechanisms that can be responsible for the observed effects.
Issues of Ge hut cluster nucleation and growth at low temperatures on the Ge/Si(001) wetting layer are discussed on the basis of explorations performed by high resolution STM and in-situ RHEED. Data of HRTEM investigations of Ge/Si heterostructures a
re presented with the focus on low-temperature formation of perfect multilayer films. Exploration of the photovoltaic effect in Si p--i--n-structures with Ge quantum dots allowed us to propose a new approach to designing of infrared detectors. First data on THz dynamical conductivity of Ge/Si(001) heterostructures in the temperature interval from 5 to 300 K and magnetic fields up to 6 T are reported.
Some possible applications of the low-angle mid-IR-light scattering technique and some recently developed on its basis methods for non-destructive inspection and investigation of semiconductor materials and structures are discussed in the paper. The
conclusion is made that the techniques in question might be very useful for solving a large number of problems regarding defect investigations and quality monitoring both in research laboratories and the industry of microelectronics
Czochralski-grown silicon crystals were studied by the techniques of the low-angle mid-IR-light scattering and electron-beam-induced current. The large-scale accumulations of electrically-active impurities detected in this material were found to be d
ifferent in their nature and formation mechanisms from the well-known impurity clouds in a FZ-grown silicon. A classification of the large-scale impurity accumulations in CZ Si is made and point centers constituting them are analyzed in this paper. A model of the large-scale impurity accumulations in CZ-grown Si is also proposed. In addition, the images of the large-scale impurity accumulations obtained by means of the scanning mid-IR-laser microscopy are demonstrated.
The terahertz spectra of the dynamic conductivity and radiation absorption coefficient in germanium-silicon heterostructures with arrays of Ge hut clusters (quantum dots) have been measured for the first time in the frequency range of 0.3-1.2 THz at
room temperature. It has been found that the effective dynamic conductivity and effective radiation absorption coefficient in the heterostructure due to the presence of germanium quantum dots in it are much larger than the respective quantities of both the bulk Ge single crystal and Ge/Si(001) without arrays of quantum dots. The possible microscopic mechanisms of the detected increase in the absorption in arrays of quantum dots have been discussed.
