H. Cánepa

Transmission electron microscopy of the induced damage by argon implantation in (111) HgCdTe at room temperature

HgCdTe (MCT) is an important semiconductor material used for infrared photovoltaic detectors. Although ion implantation is a widely used technique in the manufacture of devices based on MCT to obtain n/p junctions, a detailed understanding of the n-type behavior of the unannealed damage region has not yet been established. In this work, n/p junctions were formed by Ar++ implantation on MCT (111) grown by the isothermal vapor phase epitaxy method. Structural damage after implantation for different implantation doses (1013, 1014, and 1015 Ar++/cm2) was evaluated by transmission electron microscopy. At high doses, damage distribution exhibits a double region of defects. These were mainly vacancy dislocation loops and lines in the first region, whereas the second zone exhibited small dislocation loops. The observed n-type behavior after implantation was attributed to the generation and diffusion of Hg from the damaged region.

Characterization of single crystalline ZnTe and ZnSe grown by vapor phase transport.

Tubular furnaces were designed and built to obtain single crystalline ZnTe and ZnSe ingots using respectively physical and chemical transport methods. Different temperature profiles and growth rates were analyzed in order to optimize the necessary crystalline quality for device development. Optical and scanning electron micrographs of the corrosion figures produced by chemical etching were used to obtain the dislocation density and the misorientation between adjacent subgrains in ZnTe and ZnSe wafers. Structural quality of the single crystalline material was determined by transmission electronic microscopy. Optical transmittance was measured by infrared transmission spectrometry and the resulting values were compared to commercial samples.

Observation of CuPt and CuAu I-type ordered structure in HgCdTe grown by isothermal vapour phase epitaxy

Abstract Ordered structures, CuPt and CuAu I types in HgCdTe are reported for the first time. Hg 1− x Cd x Te thin crystals were grown by isothermal vapour phase epitaxy (ISOVPE) method on a CdTe substrate and they were observed by transmission electron microscopy (TEM) in planar view and cross-sectional geometries. Two variants of CuPt-type ordered structure were found in different microdomain sets on HgCdTe. Another superstructure observed was the CuAu I-type coexisting with CuPt domain structure.