H. L. Bhat

The physics and technology of gallium antimonide: An emerging optoelectronic material

Recent advances in nonsilica fiber technology have prompted the development of suitable materials for devices operating beyond 1.55 mu m. The III-V ternaries and quaternaries (AlGaIn)(AsSb) lattice matched to GaSb seem to be the obvious choice and have turned out to be promising candidates for high speed electronic and long wavelength photonic devices. Consequently, there has been tremendous upthrust in research activities of GaSb-based systems. As a matter of fact, this compound has proved to be an interesting material for both basic and applied research. At present, GaSb technology is in its infancy and considerable research has to be carried out before it can be employed for large scale device fabrication. This article presents an up to date comprehensive account of research carried out hitherto. It explores in detail the material aspects of GaSb starting from crystal growth in bulk and epitaxial form, post growth material processing to device feasibility. An overview of the lattice, electronic, transport, optical and device related properties is presented. Some of the current areas of research and development have been critically reviewed and their significance for both understanding the basic physics as well as for device applications are addressed. These include the role of defects and impurities on the structural, optical and electrical properties of the material, various techniques employed for surface and bulk defect passivation and their effect on the device characteristics, development of novel device structures, etc. Several avenues where further work is required in order to upgrade this III-V compound for optoelectronic devices are listed. It is concluded that the present day knowledge in this material system is sufficient to understand the basic properties and what should be more vigorously pursued is their implementation for device fabrication

Crystal growth and physical characterization of the semiorganic bis(thiourea) cadmium chloride

Single crystals of bis(thiourea) cadmium chloride (BTCC), a novel semiorganic nonlinear optical material, were grown from aqueous solutions. The grown crystals were characterized by recording the powder X-ray diffraction pattern and by identifying the diffracting planes. BTCC has a transmission that extends from 285 to 1900 nm. Differential thermal analysis carried out on BTCC indicates that the material does not sublime before it melts at 215°C. The grown crystals were estimated to have a moderate defect density. The mechanical hardness of BTCC was evaluated in the (0 1 0) plane.

Crystal growth and defects characterization of zinc tris (thiourea) sulfate: a novel metalorganic nonlinear optical crystal

Abstract Single crystals of the metalorganic nonlinear optical material zinc tris (thiourea) sulfate (ZTS) were grown from aqueous solution. The morphology of the crystals was indexed. The grown crystals were characterized by recording the powder X-ray diffraction pattern and by identifying the diffracting planes. Spectrophotometric studies on ZTS reveal that it has good transparency for the Nd: YAG laser fundamental wavelength. Differential thermal analysis of ZTS indicates that the material does not sublime before melting but decomposes immediately after melting. The defect content of the crystals was estimated using etching and X-ray topography. The mechanical hardness anisotropy was evaluated in the (100) plane, which indicates the presence of soft directions.

Laser induced damage in zinc tris(thiourea) sulfate and bis(thiourea) cadmium chloride

Laser induced damage threshold values are reported for two metal‐organic complex crystals, zinc tris(thiourea) sulfate, and bis(thiourea) cadmium chloride. These crystals have single shot and multiple shot damage thresholds which are the highest among the solution grown crystals. The damage morphology, obtained by irradiating with fluences close to the threshold, reflects the symmetry of the face of the test site. At higher fluences the damage leads to stress‐induced fracture or thermo‐chemical degradation.

Growth and defect characterization of L-arginine phosphate monohydrate

L-arginine phosphate monohydrate (LAP) is a relatively new organic nonlinear optical material. In this paper, the results of our recent investigations on the growth of this crystal are presented. The growth of the undesirable micro-organisms was prevented by protecting the solution surface by placing a thick layer of n-hexane over it. Colouration of the solution could be avoided by keeping the growth temperature low and by protecting it from light. The effect of pH value of the solution on the solubility and habit was analysed. The grown crystals were characterized by means of X-ray topography.

Critical properties in single crystals of Pr1-xPbxMnO3

The critical properties at the ferromagnetic-paramagnetic transition have been analyzed from data of static magnetization measurements on single crystals of

Thermal and electrical properties of the novel organic nonlinear crystal L-arginine phosphate monohydrate

Pr_{1-x}Pb_xMnO_3

Growth and characterization of ferroelectric glycine phosphite single crystals

for x=0.23 and x=0.30. In

Nature of compensating luminescence centers in Te-diffused and -doped GaSb

Pr_{1-x}Pb_xMnO_3

Critical properties of the double-exchange ferromagnet Nd 0.6 Pb 0.4 MnO 3

, the ferromagnetic ordering and the metal-insulator transition do not coincide in parts of the phase diagram. The crystal with x=0.23 is a ferromagnetic insulator with Curie temperature