TEM, chemical etching and FTIR characterization of ZnTe grown by physical vapor transport

Abstract

ZnTe ingots were obtained by the physical transport method, using an in‐house designed and built tubular furnace. The growth of ZnTe subsequently to the growth of a seed of this material allowed obtaining an ingot formed by only one large and single crystalline grain. TEM was used for the characterization of the as‐grown ZnTe single crystal ingots and commercial single‐crystalline wafers of the same material but grown by a higher temperature and more expensive technique, the Bridgman method. Both materials show very good crystalline microstructure, although some stacking faults were found in the commercial one. The infrared transmittance spectra of both materials were measured by FTIR and some differences, most likely due to differences in raw materials and growth methods, were found. The effectiveness and convenience of several chemical etchants to obtain the dislocation density and the minimal misorientation between adjacent subgrains in the as‐grown ZnTe wafers were checked. It has been found as the most advantageous the chemical solution that does not produce over‐etching. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Structural quality in single crystalline CdSe ingots grown by PVT

“…The material thus obtained was ground in vacuum and then heated under dynamic vacuum, at a temperature slightly lower than the melting temperature of the starting elements. This removed any volatile component non stoichiometrically combined, since the vapor pressure of such an excess component would prevent single crystalline growth [14,15] (Table 1: Processes 1 to 3).…”

“…It has to be mentioned that the later material had lower values of dislocations density and adjacent subgrains misorientation than commercial one [13] being measurements obtained by OM in both cases. No dislocations were observed by TEM in any of the commercial samples of ZnTe [14] and ZnSe [15] all of them grown by HPB. But in ZnTe [14] were detected stalking faults by TEM and in ZnSe [15] twins and occluded crystals by OM.…”

“…No dislocations were observed by TEM in any of the commercial samples of ZnTe [14] and ZnSe [15] all of them grown by HPB. But in ZnTe [14] were detected stalking faults by TEM and in ZnSe [15] twins and occluded crystals by OM. In UNIDEF ZnTe and ZnSe single crystalline ingots were not observed dislocations or stalking faults by TEM.…”

“…Characterization results of single crystalline CdSe ingots grown in our laboratory (UNIDEF) by the physical vapor transport (PVT) [12] using a horizontal reactor were compared to those of commercial single crystalline wafers of the same material grown with a higher temperature and more expensive method (HPB) [12,13] and also to PVT material grown in a vertical reactor [7] by other authors. It was important in this work to evaluate the reliability of the employed techniques in the crystalline quality determination as much as to carry out a comparative assessment of the found results to determine the quality of all materials for optical devices employment as we have previously done with ZnTe and ZnSe [14,15].…”

Propiedades físicas y cristalinas del Cd1-xZnxTe (0 ≤ x ≤ 1)

“…Se compararon los valores entre el ZnTe y el CdTe, y se observó que: la densidad de dislocaciones del ZnTe (reveladas con una solución de HNO 3 :HF, sobre el plano cristalográfico (111)) fue en promedio: 3,3 x 10 5 cm -2 y la desorientación angular de subgranos contiguos fue en promedio: 9" [15], mientras que la densidad de dislocaciones del CdTe (reveladas con una solución de Nakagawa, sobre el plano cristalográfico (111)Cd, crecido a una velocidad de 1,66 mm/h) fue en promedio: 2,5 x 10 6 cm -2 y la desorientación angular de subgranos contiguos fue en promedio: 30" [10]. En el caso del Cd 0,96 Zn 0,04 Te, crecido a la misma velocidad y revelado químicamente con la misma solución, la densidad de dislocaciones es de 2,7 x 10 6 cm -2 y la desorientación angular de subgranos contiguos fue en promedio: 29" [10].…”