Recent developments of the InP crystals are reviewed in this paper. In this review, three topics are shown. These are: (l) the reduction of the native defects in InP crystals, (2) the heat treatment effects of InP crystals, and (3) the correlation between the quality of the epitaxial layer and the dislocation in the substrate. The dislocation density of the InP crystals can be reduced by using a simple thermal baffle technology without using sophisticated technique, The existence of the facets on the body is a characteristic of low EPD InP crystals. The S-pits density decreased as the melt holding time before the crystal growth starts increased. The scattering centers investigated by IR light scattering tomography also decreased as the holding time increased. The electrical properties of the InP crystals depend on the annealing conditions. The carrier concentration of the undoped InP crystals decreased after annealing at 650℃. The hole concentration of the heavily Zn-doped InP crystals increased as the cooling rate after the annealing increased. The formation of the hillock defect on the MOCVD epitaxial layer is caused both by dislocations and by substrate orientations. There is a critical misorientation angle for the appearance of the hillock defects.
There exists a limiting thickness, d_c for epitaxial growth of Si film grown on a 7×7 superlattice surface of Si (111) held at temperatures below 300℃. In other words epitaxial film growth transforms into amorphous film growth when the film thickness approaches d_c. The value of d_c in-creases with increase in the substrate temperature (T_s) and decrease in the growth rate R. This is examined from the viewpoint that the growing surface becomes rougher with higher R and lower T_s because adequate structural rearrangement on the atomic scale is prevented. This view also leads to another thought that atomic step structure on the growing surface depends on the film growth condition. To research this, the atomic step structure change is examined by analyzing the full width at half maximum of the peak profile obtained by low-energy electron diffraction.
Numerical simulations of the CZ crystal growth of oxide are reviewed, placing the focus on the mathematical model for global analysis of heat transfer in the inductively heated CZ system. The calculated results for LiNbO_3 crystal growth are demonstrated, where the interface inversion is numerically reproduced.
Structural analysis of bariumborate (BaOB_2O_3) melts prepared from a-phase or β-phase has been described with special reference to the relationships between melt structure and crystal structure before melting. The difference of crystal structure before melting was not well recognized in the RDF data. It was, however, ascertained that the different behavior, indicating the characteristic features deduced from crystal structutes before melting, is detected in the profiles of 3rd and 4th peaks of the reduced interference function.
The Vertical Bridgman method (VB) and the Vertical Gradient Freeze method (VGF) are superior to the Gzochralski method (CZ) from the standpoint of thermal environment due to the former being low temperature gradient. In spite of this technological merit, applications of VB and VGF have been few. The reason why VB and VGF have not been popular is that these growing techniques had to wait for suitable advances in chemical, the crucible, atomosphere and raw material used. In this paper, first we consider the technological merits and problems facing the VB and VGF methods at this time. Next we present a powerful solution to these problems, namely Reactive gas Atomosphere Processing method (RAP) which is applied to the purification process of metallic halide materials. The application of RAP to halide materials results the non-sticking condition between the crystal and the crucible. This idea of RAP is also applicable to metals, semiconductors and oxides. This new development will substantially improve VB and VGF methods.
Interstitial oxygen (Oi) striations in Czochralski grown silicon single crystals have been investigated by using a micro-Fourier transform infrared microscopy (micro-FTIR) mapping system. Oi striations are quantitatively measured, and Oi micro-distribution profiles exhibit irregularity. Their peak-to-valley vallues are reduced by decreasing the crucible rotation in a horizontal magnetic field of 0.3 T. Their periodic intervals are synchronized with the doped phosphorus concentration only when a magnetic field is applied and the seed rotation rate is set at less than 1 rpm. The origin of this periodic interval is discussed in terms of a microscopic segregation effect, whose coefficient for oxygen is proposed to be less than unity.