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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Structural and Electronic Properties of Indium-Doped n-type Cd-Se-Te Crystals

Here, we present a comprehensive investigation into the potential of n-type indium-doped cadmium selenide telluride (CST:In) as a high-performance candidate for solar cell applications, without the need for resource-intensive post-growth treatments that are required for CdTe:In. We compared undoped CST and CST:In crystals under different growth conditions, analyzing their structural and electronic properties using x-ray diffraction (XRD), electron probe microanalysis (EPMA), current-voltage (IV) and Hall effect measurements, time-resolved photoluminescence (TRPL), optical transmission, and photoluminescence (PL) mapping. The results reveal that as-grown CST:In crystals achieve nearly 100% carrier activation, yielding an electron concentration of 9.5x1018 cm -3 , mobility of 653 cm 2 /V.s and a 5 ns lifetime which approaches the radiative limit. Furthermore, comparison of PL maps from crystal growths having different cooling profiles suggests a strong effect of cooling rate on selenium segregation and cubic/hexagonal/polytype phase distribution. Slower cooling leads to a more homogeneous cubic structure with lower Se segregation, while a faster cooling rate results in increased Se segregation, and twin boundaries and stacking faults with polytypic and hexagonal character.

14 SOLAR ENERGY↗
DOE OSTI2021

Developing a Low Cost, High Volume and Scalable Manufacturing Technology for Undoped and Heavily P-Type Doped CdTe Feedstock Materials (Final Report)

The goal of this project was to establish a cost-effective and scalable production approach of feedstock (CdTe and Cd-Se-Te) for the solar industry, with the material properties necessary to improve performance and reduce costs. The primary focus was to develop a CdTe synthesis and growth process that pushed the p-type doping of CdTe to previously unattainable levels, while creating a path to scalable production. In our approach, the first step was bulk CdTe growth doped with Group V dopants (P, As, and Sb) using the Modified Vertical Bridgman (MVB) and high Pressure Bridgman (HPB) techniques, and the second step was examination of films deposited by Close-Spaced Sublimation (CSS) and Vapor Transport Deposition (VTD) using this specialized feedstock.

14 SOLAR ENERGY↗
DOE OSTI2024

Characterization of n-Type Iodine-Doped and Indium-Doped CdTe/Cd-Se-Te Thin Films Fabricated by Close-Spaced Sublimation Epitaxy

In this study, n-type CdTe thin films, specifically iodine-doped CdTe (CdTe:I), indium-doped CdTe (CdTe:In), and indium-doped Cd-Se-Te (CST:In), were synthesized using close-spaced sublimation epitaxy (CSSE). Characterization techniques secondary ion mass spectrometry (SIMS), electron backscatter diffraction (EBSD), Hall-effect measurements, and time-resolved photoluminescence (TRPL) were employed to analyze the chemical, structural, and electronic properties of these materials. The results indicated epitaxial single crystal CSSE films grew on the single crystal substrates, with carrier density ranging from 10^14 - 10^16 cm -3 , and after post-annealing, the minority-carrier lifetimes reach near the radiative limit. Additionally, a preliminary exploration of homojunction structures with an n- type (CdTe:In /CST:In /CdTe:I) /CdTe:P /Cu /Mo configuration was performed. The best device performance was achieved with CdTe:I including CdS aiding in band alignment, resulting in a power conversion efficiency (..eta..) of 2.61% with open circuit voltage (Voc) of 850 mV, fill factor (FF) of 47.8%, and short-circuit current (Jsc) of 6.44 mA/cm 2 . The observed low Jsc and efficiency may be attributed to a buried junction and a poor interface, due to dopant interdiffusion. Consequently, further investigations focusing on interface optimization, diffusion blocking, and reduced recombination through passivation, are crucial to enhancing the efficiency of CSSE CdTe homojunction devices in the future.

cadmium compounds↗
DOE OSTI2020

Materials Data on Cd2TeSe by Materials Project

Cd2TeSe is Lavarevi\'{c}ite-like structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three equivalent Te2- and one Se2- atom to form corner-sharing CdTe3Se tetrahedra. All Cd–Te bond lengths are 2.83 Å. The Cd–Se bond length is 2.68 Å. In the second Cd2+ site, Cd2+ is bonded to one Te2- and three equivalent Se2- atoms to form corner-sharing CdTeSe3 tetrahedra. The Cd–Te bond length is 2.87 Å. All Cd–Se bond lengths are 2.74 Å. Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra. Se2- is bonded to four Cd2+ atoms to form SeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd4Te3Se by Materials Project

Cd4Te3Se is Enargite-like structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are four inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three equivalent Te2- and one Se2- atom to form corner-sharing CdTe3Se tetrahedra. All Cd–Te bond lengths are 2.85 Å. The Cd–Se bond length is 2.70 Å. In the second Cd2+ site, Cd2+ is bonded to one Te2- and three equivalent Se2- atoms to form corner-sharing CdTeSe3 tetrahedra. The Cd–Te bond length is 2.87 Å. All Cd–Se bond lengths are 2.77 Å. In the third Cd2+ site, Cd2+ is bonded to four Te2- atoms to form corner-sharing CdTe4 tetrahedra. There are three shorter (2.85 Å) and one longer (2.86 Å) Cd–Te bond lengths. In the fourth Cd2+ site, Cd2+ is bonded to four Te2- atoms to form corner-sharing CdTe4 tetrahedra. There are three shorter (2.85 Å) and one longer (2.86 Å) Cd–Te bond lengths. There are three inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with three equivalent SeCd4 tetrahedra and corners with nine TeCd4 tetrahedra. In the second Te2- site, Te2- is bonded to four Cd2+ atoms to form corner-sharing TeCd4 tetrahedra. In the third Te2- site, Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with three equivalent SeCd4 tetrahedra and corners with nine TeCd4 tetrahedra. Se2- is bonded to four Cd2+ atoms to form SeCd4 tetrahedra that share corners with six TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2TeSe by Materials Project

Cd2TeSe is Chalcopyrite-like structured and crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. Cd2+ is bonded to two equivalent Te2- and two equivalent Se2- atoms to form corner-sharing CdTe2Se2 tetrahedra. Both Cd–Te bond lengths are 2.84 Å. Both Cd–Se bond lengths are 2.72 Å. Te2- is bonded to four equivalent Cd2+ atoms to form TeCd4 tetrahedra that share corners with four equivalent TeCd4 tetrahedra and corners with eight equivalent SeCd4 tetrahedra. Se2- is bonded to four equivalent Cd2+ atoms to form SeCd4 tetrahedra that share corners with four equivalent SeCd4 tetrahedra and corners with eight equivalent TeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd4Te3Se by Materials Project

Cd4Te3Se is Lavarevi\'{c}ite-like structured and crystallizes in the orthorhombic Pmm2 space group. The structure is three-dimensional. there are three inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to two equivalent Te2- and two equivalent Se2- atoms to form corner-sharing CdTe2Se2 tetrahedra. Both Cd–Te bond lengths are 2.86 Å. Both Cd–Se bond lengths are 2.74 Å. In the second Cd2+ site, Cd2+ is bonded to three Te2- and one Se2- atom to form corner-sharing CdTe3Se tetrahedra. There are two shorter (2.85 Å) and one longer (2.88 Å) Cd–Te bond lengths. The Cd–Se bond length is 2.71 Å. In the third Cd2+ site, Cd2+ is bonded to four Te2- atoms to form corner-sharing CdTe4 tetrahedra. There are two shorter (2.85 Å) and two longer (2.86 Å) Cd–Te bond lengths. There are two inequivalent Te2- sites. In the first Te2- site, Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with four equivalent SeCd4 tetrahedra and corners with eight TeCd4 tetrahedra. In the second Te2- site, Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with two equivalent SeCd4 tetrahedra and corners with ten TeCd4 tetrahedra. Se2- is bonded to four Cd2+ atoms to form SeCd4 tetrahedra that share corners with two equivalent SeCd4 tetrahedra and corners with ten TeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd2TeSe by Materials Project

Cd2TeSe is Lavarevi\'{c}ite-like structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are two inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded to three equivalent Te2- and one Se2- atom to form corner-sharing CdTe3Se tetrahedra. All Cd–Te bond lengths are 2.82 Å. The Cd–Se bond length is 2.68 Å. In the second Cd2+ site, Cd2+ is bonded to one Te2- and three equivalent Se2- atoms to form corner-sharing CdTeSe3 tetrahedra. The Cd–Te bond length is 2.88 Å. All Cd–Se bond lengths are 2.74 Å. Te2- is bonded to four Cd2+ atoms to form TeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra. Se2- is bonded to four Cd2+ atoms to form SeCd4 tetrahedra that share corners with six equivalent TeCd4 tetrahedra and corners with six equivalent SeCd4 tetrahedra.

36 MATERIALS SCIENCE↗