Ferenc Riesz

Lattice misfit and relative tilt of lattice planes in semiconductor heterostructures

High resolution X-ray diffraction has been used to investigate the relative tilt between epilayer and substrate lattice planes of different semiconductor heterostructures. All epilayers were grown on (001) GaAs substrates misoriented by 2 degrees towards the next (011) direction. Results on the amount of the relative tilt and the direction of the maximum relative tilt are presented. The authors find that for heterostructures with small misfit (f 0.05) an angle of about 90 degrees between the direction of maximum relative tilt and the direction of the miscut substrate has been observed.

Geometrical optical model of the image formation in Makyoh (magic-mirror) topography

A geometrical optical model for the image formation of Makyoh (or magic-mirror) topography is presented. General relations are given on the optical settings. The basic equations of the imaging are derived. Fundamental features of the imaging are pointed out, and optimum working conditions are established. Simulations of the image of an isolated defect (hillock or depression) and a periodic (sinusoidal) surface are presented for different optical settings. Supporting experimental images are presented.

Crystallographic tilting in high‐misfit (100) semiconductor heteroepitaxial systems

A model is presented for the formation of crystallographic tilting (misorientation) in highly mismatched (100) oriented zinc‐blende semiconductor heteroepitaxial layers grown on vicinal substrates. The model is based on the asymmetric generation of 60° misfit dislocations upon island coalescence in the initial growth process and the asymmetric strain release at substrate steps, and predicts a correlation between tilt angle and initial growth planarity. Good agreement is found between model and experimental data on the GaAs/Si and other systems. It is also shown that, if the net tilt is small, an azimuthal rotation of the tilt axis may occur, even if the system symmetry would hinder it. The influence of thermal annealing and thermal mismatch on the tilt is discussed as well.

Crystallographic tilting in lattice‐mismatched heteroepitaxy: A Dodson–Tsao relaxation approach

Asymmetric strain relaxation and the concomitant misorientation (tilt) of the lattice planes of the epitaxial layer in lattice‐mismatched heterostructures is analyzed theoretically. The kinetic relaxation model of Dodson and Tsao [Appl. Phys. Lett. 51, 1325 (1987); 52, 852(E) (1988)] is extended to the growth on vicinal surfaces. We calculate the equilibrium tilt values as well as the evolution of tilt during strain relaxation as a function of material parameters, initial defect densities, and substrate miscut angle. Literature data are interpreted within the framework of the model.

Tilting of lattice planes in InP epilayers grown on miscut GaAs substrates: the effect of initial growth conditions

Abstract The relative misorientation (tilt) between the epilayer and substrate (400) lattice planes of InP epilayers grown on (100) GaAs substrates misoriented towards the (100) plane was studied by high resolution X-ray diffraction. The epilayers were grown by gas-source molecular beam epitaxy. For the growth temperature of 490–500°C, the direction of the relative tilt was nearly coincident with the direction of the lattice plane tilting of the substrate, according to previous models. In contrary, when a buffer layer was deposited at a lower temperature of 400–450°C prior to growth, an azimuthal rotation of about 45° was found between the directions of the relative tilt and the substrate lattice plane tilting. In order to explain the results, a temperature-dependent anisotropic nucleation model is proposed. The effect of misfit dislocations is also considered.

Makyoh topography for the morphological study of compound semiconductor wafers and structures

The application of Makyoh topography in the assessment of flatness and overall curvature of semiconductor wafers and layer structures is reviewed, with special emphasis on compound semiconductors. Application examples are shown as well.

Thermal decomposition of bulk and heteroepitaxial (100) InP surfaces: A combined in situ scanning electron microscopy and mass spectrometric study

The thermal decomposition of bulk and heteroepitaxial (100) InP surfaces is studied by in situ scanning electron microscopy combined with mass spectrometry. The onset of P evaporation coincides with the In droplet nucleation at about 480 °C and the major evaporation of phosphorous commences above 510 °C and corresponds to the serious deterioration of the surface. There is no significant difference between bulk and defected (heteroepitaxial InP/GaAs) samples. The relevance to InP technology is discussed.

Can epilayer tilt relieve misfit strain in lattice-Mismatched heterostructures?

Small tilting of the epilayer lattice planes is commonly observed in lattice-mismatched epilayers grown on vicinal substrates. This tilt is commonly believed to be an alternative strain-relieving mechanism to the formation of misfit dislocations. It is shown that this is not likely for (100) heterosystems, because the introduction of those dislocations is favorable which relax misfit rather than those which induce tilt. The model shows good agreement with experimental observations.

Carrier Profiling of a Heterojunction Bipolar Transistor and p-i-n Photodiode Structures by Electrochemical C-V Technique

Carrier profiling of GaAs/GaAlAs multilayer structures (heterojunction bipolar transistor and heterojunction p-i-n photodiode) by electrochemical capacitance-voltage technique is described. Optimum measurement parameters (electrolyte type, etching and measurement voltages, etc.) are established. The results are compared with those of spreading resistance profiling and transmission electron microscopy. Some specific problems are discussed.

Rotated tilting in lattice-mismatched heteroepitaxial systems

Abstract The misorientation of epilayer lattice planes in lattice-mismatched heterostructures is discussed. The geometry of the tilt reflects the overall symmetry of the system. Thus, rotation of tilt axis contains information on the anisotropy of dislocation nucleation/glide in low misfit, and on the initial growth processes in high misfit systems. In coherent systems, no rotation is expected. The model shows good agreement with experimental observations.