Estudio de las propiedades del Hg1-xCdxTe crecido por el Método de Bridgman y de Epitaxia en fase vapor

Fil: Trigubo, Alicia Beatriz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Simulation of Single Crystalline CdZnTe Solidification Process

Single crystals of Cd1-xZnxTe (0 ≤ x ≤ 0.1) (CZT/CdZnTe) are used in manufacture of gamma and X-ray detectors and as substrates for epitaxial growth of HgCdTe. Computer simulation for the solidification of CZT was performed using finite elements. The simulation results indicate that a lower translation speed of the quartz ampoule within the Bridgman furnace determines a lower concavity of the liquid interface which assures a good crystalline quality. When the rate is 3.32 mm/h the concavity is 58% greater than for a speed of 0.50 mm/h. It was experimentally found that when growing at low speed, 1.66 mm/h, the process is more stable and improves the crystalline quality due that only two grains were generated in CZT ingots. Meanwhile a faster growth speed- 3.32 mm/h- generates a large amount of grains in the CZT ingot.Fil: Martinez, Ana Maria. Provincia de Misiones. Comite de Desarrollo E Innovacion Tecnologica; ArgentinaFil: Rosenberger, Mario Roberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégicos Para la Defensa; Argentina. Universidad Tecnologica Nacional; ArgentinaFil: D'elia, Raul Luis. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; ArgentinaFil: Heredia, Eduardo Armando. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas Para la Defensa; Argentin

Structural quality in single crystalline CdSe ingots grown by PVT: Qualidade estrutural em lingotes de CdSe monocristalinos crescidos por PVT

CdSe is II-VI semiconductor with compact hexagonal structure. It has a band gap of 1.82 eV and a high stopping power for nuclear radiation. Single crystalline CdSe ingots were grown by Physical Vapor Transport (PVT) employing a horizontal reactor. As devices critically depend on material properties its single crystalline quality was determined by chemical etching and transmission electron microscopy. Results were compared to those corresponding to Bridgman High Pressure (HPB) grown material and also to PVT material grown in a vertical reactor.O CdSe é um semicondutor II-VI com estrutura hexagonal compacta. Tem uma banda proibida de 1,82 eV e um alto poder de freamento de radiação nuclear. Os monocristais de CdSe foram crescidos por transporte físico de vapor (PVT), empregando um reator horizontal. Como os dispositivos dependem criticamente das propriedades do material, sua qualidade cristalina foi determinada por ataque químico e microscopia eletrônica de transmissão. Os resultados foram comparados com aqueles correspondentes ao material crescido pelo método Bridgman vertical de alta pressão (HPB) e também com o material PVT crescido em um reator vertical.Fil: D'Elía, Raúl Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Aguirre Myriam Haydee. Universidad de Zaragoza. Facultad de Ciencias. Departamento de Física de la Materia Condensada; EspañaFil: Di Stefano, María Cristina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Heredia, Eduardo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Martínez, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Canepa, Horacio Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Núñez García, Javier Luis Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentin

Estudio de las propiedades del Hg1-xCdxTe crecido por el Método de Bridgman y de Epitaxia en fase vapor

Fil: Trigubo, Alicia Beatriz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

ISOVPE MCT films grown on pure and alloyed CdTe substrates with different crystalline orientations

Epitaxial films of Hg1-xCdxTe (MCT) with x≅0.2 were grown on CdTe, Cd0.96Zn0.04Te and CdTe0.96Se0.04 substrates by the isothermal vapor phase epitaxy (ISOVPE) technique with no mercury overpressure. The growth was accomplished in different crystallographic orientations: (1 1 1)Cd, (1 1 1)Te, (1 1 0) and (1 0 0). The structural characterization of substrates and films was performed by X-ray diffraction (Laue technique), surface chemical etching and optical microscopy. Chemical composition analysis was performed by an electronic microprobe in the wavelength dispersive spectroscopic mode and electrical characterization by Hall effect measurements. MCT is an important semiconductor for the manufacture of infrared detectors. The alloyed substrates have a closer lattice match with Hg1-xCdxTe. Furthermore, these substrates usually have a lower dislocation density. Both facts determine a lower generation of lineal defects during growth. This fact could produce a larger carrier lifetime and, as a consequence, better electrical properties of devices. On the other hand the surface morphology of ISOVPE MCT epitaxial films only depends on the crystallographic orientation, being independent of the use of pure or alloyed substrates.Fil: Gilabert, Ulises Eduardo. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Heredia, Eduardo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentin

Mechanical Properties Calculation of II-VI Semiconductors: Cd (1-y)Zn(y)Te (0<y<1)

Mechanical properties of semiconductors: CdTe, ZnTe and CdTe alloyed with 2 at% and 5 at% of Zn have been calculated, using the computer code WIEN2k. The program uses the Density Functional Theory. The results show that increasing the amount of Zn, results in greater values of mechanical properties and contraction of the lattice parameter since replacement of Cd by Zn establish lower Zn-Te distance compared with Cd-Te. The behavior is different for the C12 constant of Cd0.90Zn0.10Te, the shear and Young modulus of CdTe. Meanwhile Poisson´s ratio is constant. The calculated values for CdTe and ZnTe differ from the experimental values between 8% and 21%. The calculated values differ from others authors between 2% and 21%. There are no experimental data of the alloyed CdTe. Values of CdTe alloyed whit Zn are between the CdTe and ZnTe closest to the CdTe. Differences with data calculated by other authors are noticeable.Fil: Martínez, Ana María. Provincia de Misiones. Comité de Desarrollo e Innovación Tecnológica. Centro de Desarrollo e Innovación Tecnológica; ArgentinaFil: Soriano, Rosario. Universidad Tecnológica Nacional; ArgentinaFil: Faccio, Ricardo. Universidad de la República; UruguayFil: Trigubo, Alicia Beatriz. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentin

Growth kinetics of ISOVPE HgCdTe epilayers obtained on alloyed CdTe substrates with different crystalline orientations

Hg1-xCdxTe (MCT) epilayers were grown on (1 1 1)Cd, (1 1 1)Te, (1 1 0) and (1 0 0) CdZnTe and CdTeSe substrates by isothermal vapor phase epitaxy (ISOVPE). The growth kinetics of the epilayers were studied by a non-linear diffusive convective model for the ISOVPE MCT growth, which was assessed in a previous paper . The non-linear diffusion–convection problem, which describes ISOVPE MCT film growth, was numerically solved by means of discrete mathematics. As the theoretical and experimental composition profiles were remarkably different in accordance with the epilayers grown over pure CdTe substrates, in the model a finite rate in the surface reaction rate constant that enabled a good fit was assumed. The numerical value of the surface reaction rate constant was similar for all the studied substrates and crystalline orientations, hence the results enabled us to determine that the deposition rate has a mixed control for the experimental conditions of this work. This isotropic characteristic of the ISOVPE technique for pure and alloyed CdTe substrates is remarkable, quite different from other MCT growth techniques as MBE or MOCVD.Fil: Gilabert, Ulises Eduardo. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Moyano, Edgardo A.. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Scarpettini, Alberto Franco. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Universidad Tecnológica Nacional. Facultad Regional Delta; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; Argentin

Assessment of a non-linear diffusive-convective model for the ISOVPE MCT growth

Hg1-uCduTe (MCT) is the most important semiconductor for infrared detection. The ISOVPE technique allows good quality MCT epilayers . For technological and scientific reasons it is interesting to have a model which accurately describes this MCT growth technique. Hence, a non-linear diffusion-convection problem which describes ISOVPE MCT film growth was numerically solved by means of discrete mathematics. It has been found that the model describes a diffusion-limited process in accordance with the experimental evidence. As the theoretical and experimental composition profiles were remarkably different in accordance with other authors, it was supposed in the model that a finite rate in the surface reaction enabled a good fit. A numerical value of the surface reaction constant rate was obtained for the experimental conditions of this work which enabled us to determine that the deposition rate has a mixed control. It is expected that the control of the surface reaction rate becomes more important when a lower growth temperature is used.Fil: Moyano, Edgardo A.. Comisión Nacional de Energía Atómica; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Scarpettini, Alberto Franco. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Gilabert, Ulises Eduardo. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; Argentina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; Argentin

Properties of Hg 1-xCd xTe epitaxial films grown on (211)CdTe and (211)CdZnTe

Hg 1-xCd xTe (MCT) epitaxial films have been grown employing single crystalline substrates of CdTe and Cd 0.96Zn 0.04Te with (211)Cd and (211)Te crystalline orientations. The Isothermal Vapor Phase Epitaxy (ISOVPE) technique without Hg overpressure has been used for the epitaxial growth. Substrates and films were characterized by optical microscopy, chemical etching and x ray diffraction (Laue technique). The electrical properties were determined by Hall effect measurements. The characterization results allowed to evaluate the crystalline quality of MCT films.Fil: Di Stefano, María Cristina. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Heredia, Eduardo Armando. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas; ArgentinaFil: Gilabert, Ulises Eduardo. Universidad Tecnológica Nacional. Facultad Regional Buenos Aires; ArgentinaFil: Trigubo, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; Argentin