Growth kinetics of GaSb by metalorganic vapor phase epitaxy

The growth rates of GaSb by metalorganic vapor phase epitaxy were studied as functions of growth temperatures and partial pressures of precursors. A Langmuir-Hinshelwood model was used to explain the GaSb growth rate in the chemical reaction controlled regime. The relationship between growth kinetics and epilayer qualities was discussed and properties of GaSb were obtained.     

A new N-type doping precursor for MOCVD-IMP growth of detector quality MCT

A new indium precursor, triisopropyl indium (TIPIn), has been used for doping MCT at low carrier concentrations. Previous attempts using indium organometallics resulted in a strong memory effect where residual doping would persist for many growth runs. Introducing TIPIn on the tellurium inject line resulted in a similarly strong memory doping but this was not observed when feeding the dopant in on the cadmium injection line. The TIPIn is believed to have been forming a low volatility adduct with diisopropyl tellurium (DIPTe) in the feed line and to have continued to evaporate at a low but significant rate. By keeping the TIPIn and DIPTe precursors separate until they entered the reactor, the desired low 10¹⁵ cm⁻³ carrier concentration and flat indium profiles could be achieved with good reproducibility. Good electrical characteristics were measured for these layers with Auger limited lifetime >1 μs at 77K.     

Mechanism of fe impurity incorporation into semi-insulating gaas crystals

Total concentration of Fe impurity in Cr-doped semi-insulating GaAs crystals grown by various techniques was analyzed by atomic-absorption spectrophotometry. Analytical results show that Fe contamination likely occurs during HB-crystal growth. The Fe contamination may have originated mainly from the sandblasting procedure of the silica boat with impure abrasive. The interaction between the sandblasted boat surface and the GaAs melt was found to play an important role in the Fe impurity incorporation. It was also found that most of the Fe impurity is not incor-porated as elementary Fe in the HB-grown crystals. As far as the Fe contamination is concerned, direct synthesis LEC techniques seem to be the most advantageous at present.     

Preparation and properties of AgInS2 and AgInSe2 Single crystals and of the Quaternary alloys AgInSe2(1−x)S2x

Summary AgInS₂ and AgInSe₂ single crystals have been prepared by chemical transport with iodine and by the Bridgman method. Syntheses of the quaternary alloys AgInSe_2(1−x)S_2x have also been carried out. The splittings of the uppermost valence bands in orthorhombic AgInS₂ have been determined from the photoconductivity spectrum. The lattice parameters, the energy gap, the magnetic suceptibility and the melting point of all the materials are presented. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.     

Synthesis of Graphene and Its Applications: A Review

Graphene, one-atom-thick planar sheet of carbon atoms densely packed in a honeycomb crystal lattice, has grabbed appreciable attention due to its exceptional electronic and optoelectronic properties. The reported properties and applications of this two-dimensional form of carbon structure have opened up new opportunities for the future devices and systems. Although graphene is known as one of the best electronic materials, synthesizing single sheet of graphene has been less explored. This review article aims to present an overview of the advancement of research in graphene, in the area of synthesis, properties and applications, such as field emission, sensors, electronics, and energy. Wherever applicable, the limitations of present knowledgebase and future research directions have also been highlighted.     

Growth and thermal studies on pure ADP,KDP and mixed K1‐x(NH4)xH2PO4 crystals

The investigations on the formation of mixed crystals of ammonium dihydrogen orthophosphate (ADP) and potassium dihydrogen orthophosphate (KDP) i.e. potassium ammonium dihydrogen phosphate, K_1‐x(NH₄)_xH₂PO₄ have been presented in this paper. Pure and mixed crystals of ADP and KDP have been grown by slow evaporation technique from the supersaturated solution at an ambient temperature 26±1 °C for ammonium concentration x in the range 0.0 ≤ x ≤ 1.0 in the case of mixed crystals. Crystal compositions were determined by flame atomic absorption spectroscopy and chemical analysis. The results of the X‐ray analysis of the grown crystals are also reported. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study the kinetic process of dehydration and the high temperature phase behaviour. DTA showed the distinct thermal events attributed to dehydration of ADP, KDP and K_1‐x(NH₄)_xH₂PO₄. The results of thermal analysis and chemical analysis are consistent with each other. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)