Ingot Growth Research Articles

Liquid encapsulated Czochralski growth of 35 mm diameter single crystals of GaP

Liquid encapsulated growth of GaP is complicated by two features not present in ordinary Czochralski growth: molten B 2O 3 encapsulates the melt, and high pressure gas (55 atm) fills the growth chamber. The growth of large ingots of GaP (200 g, 35 mm diameter) under these conditions is more difficult than the previously described growth of smaller ingots. Diameter control is more difficult, and the large ingots often crack spontaneously. In the liquid encapsulated Czochralski process, the growth conditions are dominated first by radiative heat transfer and later by convective heat transfer. Evidence to support this conclusion includes the shapes of growing crystals and the configurations of the growth interface. By using a knowledge of the heat transfer mechanisms, a reliable technique has been developed for adjusting rf power input to obtain uniform diameter single crystals. Unless precautions are taken, however, such ingots will crack spontaneously. The vertical temperature gradient in the growth chamber can be as high as 500 °C/cm. The resulting thermal stress causes plastic deformation in the growing ingots, leading to frozen-in stresses which may exceed the yield stress of GaP. These stresses have been reduced sufficiently to avoid cracking by using an afterheater which is an integral part of the rf susceptor. The use of an afterheater can lead to the occurrence of twin lamellae, but these have been eliminated by using a suitably shaped crucible (e.g., flat bottomed).

Melt growth of single crystal ingots of GaSe by Bridgman-Stockbarger's method

Melt growth of GaSe single crystals by Bridgman-Stockbarger's method in ampoules with differently shaped bottoms has been investigated. It has been shown that the crystal perfection depends on the lowering rate and on the ampoule diameter and that the crystal orientation depends on the bottom shape and on the position of the ampoule with respect to the furnace isotherms.

Preparation, single crystal growth, and characterization of PtSi and PtGe

Due to the highly exothermic reaction of platinum with molten silicon or germanium, a special self-regulating method was employed to produce large polycrystalline ingots of PtSi and PtGe. The equipment and techniques used for the syntheses of materials and the growth of large single crystal ingots are presented. Resistivity, Seebeck coefficient, molar susceptibility, and bulk density were measured and are reported. Both materials showed temperature independent diamagnetism from 4K to 300K.

Interface properties of oxidized silicon in dendritic web form

Abstract The praparation of silicon by the dendritic web process presents an intereating altsrnativc to the present ingot growth method since flat crystallographic surfazos can be obtained without mechanical processing. A comparative evaluation of the silicon—silicon oxide interface for web material has been carried out using the MOS capacitance method. The effect on trapped charge density of growth temperature and also of annealing the interfaces at temperatures between 680°C and 1200°C has been evaluated for both web and ingot material. The general behaviour for the dependence of trapped charge density on oxidation temperature for both web and ingot material is in good agreement with previous results for ingot material reported by Deal, Sklar, Grove and Snow (1967). However, an anomalous behaviour upon annealing has been observed for both web and ingot material which has not been previously reported. This involves a reversible increase of the trapped charge density upon annealing, with a maximum effect ...

The Low‐Temperature Thermoelectric Power and Thermal Conductivity of GeTe and of Some GeTe‐MnTe Alloys

AbstractA method of preparation has been developed which allows the growth of large homogeneous single phase ingots of such alloy systems as GeTe‐MnTe, GeTe‐SnTe, etc. … We have measured the thermoelectric power and the thermal conductivity of both GeTe and two alloys of the system Ge1−xMnxTe, in the temperature interval 2.5 to 110 °K, the thermoelectric measurements being extended to 350 °K. Using conventional transport theory both the lattice and the electronic contributions to these effects have been obtained. The temperature dependence of these properties was found to be of similar shape for the GeTe‐MnTe samples as for the pure GeTe, even below the known magnetic transition temperature of these samples. To explain the behaviour of the diffusion term of the thermoelectric power, however, the influence of the incomplete Mn d‐band on the electronic properties of the system must be invoked. The lattice thermoelectric power has the same temperature dependence as the phonon‐drag term in metals. From the analysis of both this component and the lattice thermal conductivity, some informations on the predominant phonon scattering mechanisms have been obtained.

Growth and Dislocation Structure of Single-Crystal Ga (As1−xPx)

The preparation of single-crystal GaAsP by halide vapor transport is described. That dislocation free GaAsP can be achieved was verified experimentally for whiskers grown by the vapor-liquid-solid method. In the growth of monocrystalline ingots for device purposes, growth mechanics and the resulting crystal habit are strongly influenced by degenerate Zn, Te, and Se doping. Since n-type crystals require higher supersaturations, single-crystal growth is easier to obtain with Zn doping. The as-grown dislocation structure of ingots with low-index natural facets is examined by decoration and etching. Typical densities are 5×103 to 106/cm2. From their simple crystallographic orientations different dislocations are identified. 〈211〉, {111} and 〈100〉, {110} edge dislocations are observed in {110} polygonization walls. Values of mobility and carrier density are evaluated from a device point of view. Laser diodes with threshold currents as low as 3000 A/cm2 at 33.3% GaP have been obtained from this material.