Progress in Crystal Growth and Characterization最新文献

Zinc selenide (ZnSe) is a useful semiconductor for homojunction or heterojunction optoelectronic devices. In this paper we review the fabrication techniques of vapor phase epitaxy (VPE) and metalorganic chemical vapor deposition (MOCVD) for the growth of ZnSe epilayers. These techniques can play important roles in achieving ZnSe blue light-emitting devices. Recent and future trends in growing these devices are also reviewed and studied.

The major objectives of solar cell research and development programmes are to improve the efficiency, stability and lifetime of photovoltaic devices. However, for terrestrial applications, the reduction in the basic cost of the cell is an important obstacle to overcome. The purpose of this study is, therefore, to review some of the more widely used, low-cost, non-vacuum deposition techniques; namely, spray pyrolysis, screen printing and electrodeposition. Each is dealt with under three main headings. These include (a) historical background and general aspects, (b) up-to-date description of the status of materials compatible with the deposition techniques and (c) structural, electrical and optical properties of deposited thin/thick films.

A review is presented of the synthesis of carbon films with diamond and diamond-like structures by condensing ion beams and by ionic, plasma, chemical and other methods of deposition. The influence of the thermal and electric activation of the gas phase on the process of producing films with different types of carbon bonds has been considered. Considerable attention has been paid to clarification of the conditions for the selective growth of diamond and the factors determining the formation of a predominantly tetrahedral coordination of carbon atoms in diamond-like films. Mechanical, optical and other properties of the films have been related to the temperature of the substrate and the energy of condensing particles. It has been noted that the thermostability of polycrystalline diamond layers is noticeably better than that of quasi-amorphous diamond-like ones, even though the microhardness of the latter may be the same order as that of natural diamond. Prospects for applying diamond and diamond-like films as wear-resistant, corrosion-proof and dielectric coatings have been discussed.

This paper reviews the present status of crystal growth from boiling solutions. The understanding of the peculiar characteristic of this technique: high rates of growth, restricted aplicability to substances presenting complexing phenomena in solution, high crystal perfection, etc, makes interesting to analyze the structure of saturated solutions and the nature of crystal growth units.

After a discussion of the role of complex formation and solute association, metastable zone width, crystal solution interface and bubbling in boiling solutions in applying this technique, the experimental set-ups reported so far are narrated.

Finally, the macro and micromorphology, the growth kinetics and the perfection of the obtained crystals are described and discussed.

A review is given of the methods which have been used to grow single crystals and epitaxial layers of gallium nitride. In view of the problems in growing bulk crystals, the main emphasis is on heteroepitaxy. Sapphire has been the most popular substrate material, but leads to severe stress because of lattice and expansion mismatch. The use of an intermediate AlN layer appears to alleviate this problem. Chemical vapor deposition using gallium chloride and ammonia has given the highest quality layers to date, but a native donor remains a persistent problem. The use of high pressures of nitrogen offers promise as a means of reducing the native donor concentration. Atomic layer epitaxy is an alternative technique which looks promising for film deposition under well-controlled conditions. The properties of GaN and device considerations are included briefly in this review.