Compound Crystal Growth Research Articles

In-situ observation of compound crystal growth from supercooled melt

In-situ observation of compound crystal growth from supercooled melt

Crystal growth of compounds on Si substrates

Crystal growth of compounds on Si substrates

Edge effects in intermetallic compound crystal growth between Nb and molten 52In–48Sn solder

A solder/substrate couple consisting of a Nb substrate and eutectic 52In–48Sn solder shows promise for high-temperature liquid solder interconnects. In this letter, the intermetallic compound (IMC) crystal growth between vacuum-sputtered Nb film and molten 52In–48Sn solder at four temperatures; 192, 220, 240, and 260°C, was investigated employing samples with a solder/substrate interface area of 7mm by 7mm. It was found that at all four temperatures, the IMC crystals nucleated and grew first at the corners of the substrate, followed by the edges, and then gradually covered the entire interface. This result, can be explained if the initiation of IMC crystal growth is diffusion controlled, and the value of the Nb diffusion coefficient is estimated with the aid of a three-dimensional numerical simulation.

Development of Electrode Materials for Semiconductor Devices

Recent strong demands for optoelectronic communication and portable telephones have encouraged engineers to develop optoelectronic devices, microwave devices, and high-speed devices using heterostructural compound semiconductors. Although the compound crystal growth techniques had reached at a level to control the compositional stoichiometry and crystal defects on a nearly atomic scale by the advanced techniques such as molecular beam epitaxy and metal organic chemical vapor deposition techniques, development of ohmic contact materials (which play a key role to inject external electric current from the metals to the semiconductors) was still on a trial-and-error basis. Our research efforts have been focused to develop, low resistance, refractory ohmic contact materials using the deposition and annealing techniques for n-GaAs, p-ZnSe, InP, p-SiC p-CdTe etc. It was found the growth of homo- or hetero–epitaxial intermediate semiconductor layers (ISL) was essential for low resistance contact formation. The importance of hetero-structural ISL was given taking an example of n-type ohmic contact for GaAs.

Combined molecular beam epitaxy and diffractometer system for in situ x-ray studies of crystal growth

A combination of a molecular beam epitaxy (MBE) machine and a six circle diffractometer has been constructed at a dedicated wiggler beamline at the storage ring BESSY II for in situ investigations of III–V compound crystal growth. The growth conditions in our system reach a high MBE standard with a noncooled base pressure of 2×10−10 mbar. A fast entry load lock is available for sample exchange. Large-area Be windows in the ultrahigh vacuum chamber allow us to measure reflections at entrance and exit angles up to 45°, i.e., large perpendicular momentum transfers are possible. In situ reflection high energy electron diffraction and x-ray fluorescence measurements can be performed simultaneously with x-ray scattering. A GaAs(001) surface prepared and examined in our system reveals terrace widths of 450 nm and β(2×4) reconstruction domain sizes of 210 nm. The possibility of time-resolved x-ray diffraction studies is demonstrated by observation of intensity oscillations during layer-by-layer homoepitaxial growth on the GaAs(001)β(2×4) surface. The resolution functions of our experiment are determined.

Crystal growth of compounds in the MgO-Nb205 binary system

In the system MgO-Nb2O5, four compounds are known to exist. MgNb206 is congruently melting at 1570°C while the compounds (Mg,Nb)O2.42, Mg5Nb4OI5 and Mg4Nb209 decompose peritectically at 1445, 1580 and 1730°C, respectively. Small crystals of all four compounds were grown by the laser-heated pedestal growth (LHPG) method. The Nb205-rich compounds showed some tendency to partial reduction of Nb5+ even when grown in an 02 atmosphere, resulting in a bluish-black color in the as-grown crystals. In contrast to this, the MgO-rich compounds were colorless, even though they were grown at higher temperatures. We also report the luminescence and Raman spectra of the four compounds.

Maskless all-UHV process for III-V compound semiconductors

Abstract A concept of all-UHV (ultra-high vacuum) resistless process for III-V compound semiconductors is described. This new technology is based on focused ion beam (FIB) doping and molecular beam epitaxy (MBE) in a clean-UHV environment. The submicron-diameter focused ion beams (FIBs) of multiple ion species, which are emitted from a field emission liquid metal ion source (LMIS) are powerful tools for maskless etching, doping, and deposition. Recent developments in FIB processes for III-V compound semiconductors are described, including multicomponent liquid metal ion sources, a focused ion beam implanter, and the physical characteristics of implanted GaAs. Second, preliminary tests of a new compound crystal growth system consisting of MBE layer growth linked with the maskless FIB doping are described. This new technique has been actually used to fabricate planar structures suitable for electrical and optical device integration. Third, innovative UHV processes using electron and photon beams are describ...

Cd4GeS5, a new ternary compound Crystal growth, space group and unit-cell dimensions

Cd₄GeS₅, a new ternary compound Crystal growth, space group and unit-cell dimensions