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 cm²/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.. Authors: Shang, Jing [Washington State Univ., Pullman, WA (United States)]; Murugesan, Magesh [Washington State Univ., Pullman, WA (United States)]; Gul, Rubi [Washington State Univ., Pullman, WA (United States); iRay Technology, Solon, OH (United States)]; Bigbee-Hansen, Samuel [Washington State Univ., Pullman, WA (United States)]; Tallan, Joseph M. [Washington State Univ., Pullman, WA (United States)]. DOE Contract: AC36-08GO28308; EE0007537; EE0008548. Subjects: 14 SOLAR ENERGY; 36 MATERIALS SCIENCE; Cd-Se-Te; Hall effect; MATERIALS SCIENCE,SOLAR ENERGY; crystal growth; photoluminescence mapping; solar cells; time-resolved photoluminescence