B.R. Pamplin

Growth of some single crystal II–IV–V2 semiconducting compounds

Abstract The growth of some single-crystal high-energy-gap II–IV–V2 compounds (ternary analogues of the III–V compounds) using both solution and vapour-growth techniques is described. The technique of solution synthesis is found to be particularly useful in the preparation of those compounds which dissociate near their melting point, except for the case of MgSiP2 where the compound SiP2 forms preferentially.

The solid state controlled growth of sulphides and selenides of Ag and Cu using crystal rotation

Abstract An improved crystal growth method for ionic-electronic mixed conductors, such as the high temperature cubic modifications of Ag2X and Cu2X (where X = S or Se), is presented. Ag or Cu atoms are mobile in these compounds. If the respective sulphur or selenium vapour pressure was sufficiently high at the growth surface, the growth rate was limited by the solid state chemical diffusion of Ag or Cu atoms which was controlled by the rate of the injection of the metal atoms into the compounds. The crystals were grown in a silica ampoule, held in a vertical two zone furnace and rotated at 1 rpm about the vertical axis to achieve a uniform axial temperature distribution. Nearly cylindrical single crystals of size about 3–10 mm diameter, 10–35 mm long were grown by this method.

Epitaxial growth of solid solutions of ZnSiP2 in Si

Abstract A new method of epitaxial growth of some solid solutions between group IV elements and II-IV-V 2 diamond-like semiconductors is described. The method involves traversing an appropriate solvent across a slice of germanium or silicon under a temperature gradient in the presence of the vapour of a II-IV-V 2 compound in a sealed ampoule. The technique has been applied to the growth of solid solutions of Si in ZnSiP 2 with a content of 5% ZnSiP 2 . The best solvents for the liquid zone have been found to be gold and silver.

Critical review of the growth of II–IV–V2 compounds☆

Abstract Various II-IV-V 2 compounds have been grown in single crystal form by melt, vapour and metal solution growth techniques. The literature on this is summarised in a table for the 24 known compounds. The application of accelerated crucible rotation techniques and careful temperature programming to metal solution growth has produced a tenfold increase in crystal size.

Growth of new spinel compounds CuInSnS4 and CuIn11S17

Two new spinel structure compounds CuInSnS4 and CuIn11S17 are reported. The latter has the same composition formula as the superionic distorted defect spinel compound β-alumina. They were prepared by the reaction of alloys of the metals with sulphur vapour. The lattice parameters are 10.4938 ± 0.0002 and 10.73004 ± 0.0003 A respectively. Single crystals of CuInSnS4 were grown by temperature gradient annealing of powdered CuInSnS4 at 680°C. Well faceted {111} habit crystals were produced and examined by electron probe microanalysis to confirm the composition. It is thought that these crystals grew by chemical diffusion and vapour growth in the vapour state controlled mode.

Epitaxial growth of germanium on II–IV–V2 substrates

Abstract Using open tube iodine vapour transport, epitaxial layers of germanium have been deposited onto crystals of the chalcopyrite structure semiconductors ZnSiP 2 , ZnGeP 2 and ZnSiAs 2 .

Thermal oscillations in liquids of low prandtl number

Abstract Spontaneous temperature oscillations have been found to occur in the melts from which metal and semiconductor crystals are grown when a minimum temperature gradient has been exceeded, causing impurity banding and undesirable properties. These oscillations are here studied in an annular bath using mercury as the working fluid. The amplitude of the oscillations is found to reach a peak of about 1°C at certain aspect ratios, analogous to resonance. It is believed that these peaks are caused by the presence of two or four counter-rotating “rolls” of liquid. It is suggested that growers of crystals from the melt should pay attention to the geometry of their vessels as well as to temperature gradients.

CuGe2P3 and its alloys with Ge

Abstract CuGe2P3 is a p-type semiconductor with a zinc blende structure. Even when doped with Zn or S it is heavily p-type with p = 1020cm-3 and μp = 3cm2v-1s-1. DTA studies show that it melts at 830°C and shows no structural change. Single crystal samples have been grown using a Bridgman method and a steep temperature gradient. X-ray powder photographs reveal a lattice parameter of 5.3678 A and a coefficient of expansion of 8.2 10-6. It forms alloys with Ge up to CuGe5P3 and the lattice parameter increases to 5.4581 A. These alloys are also heavily p-type.

Liquid phase epitaxial growth of CuGaS2

Abstract Solution growth of CuGaS2 from In, Sn and Ga solvents was examined with a view to selecting a suitable solvent for epitaxial growth for LED applications. In and Sn were found suitable for LPE above 580°C and 750°C respectively. Using In solvent LPE growth of CuGaS2 on ZnSe substrates was achieved in a standard sliding boat system. Best results were obtained from 610°C to 580°C on {111} B substrate orientation. Below 580°C precipitation of InS occurs sponteneously. However observed electroluminescence is broad orange emission not the expected green. Photoluminescence at 77 K using the 4416 A line of a HeCd laser as excitor showed bright yellow orange emission. In no samples was the green edge emission or the bound exciton line emission observed.

Negative differential conductivity effects in semiconductors

Abstract The discovery of the Gunn Effect has been heralded as the greatest breakthrough in semiconductor physics since the discovery in 1948 of transistor action in germanium. This article shows the basic physics of the effect and lays emphasis on the physics and applications of devices in which there is a bulk negative differential conductivity. Exciting new possibilities are opened up in the microwave region by a range of devices based on the peculiar properties of high field domains in semiconductors like GaAs.