Engineering Interface Composition for Passivation of HgCdTe Photodiodes |
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Authors: | Pal R Malik A Srivastav V Sharma BL Balakrishnan VR Dhar V Vyas HP |
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Affiliation: | Solid State Phys. Lab., Delhi; |
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Abstract: | A compositionally graded surface layer has been created for the passivation of Hg1-xCdxTe photodiodes. The graded CdTe-Hg1-xCdxTe interface was created by deposition of CdTe and subsequent annealing. It was found that the composition gradient and width of the graded region could be tailored by adopting a suitable annealing procedure. The effect of grading on the interface electrical properties and photoelectrical properties was studied by X-ray photoelectron spectroscopy (XPS), photoconductive decay, and C-V measurements. Insulator fixed-charge density and interface-trap density could be reduced to 3times1010 cm -2 and 2times1010 cm-2middoteV-1, respectively, by creating a graded interfacial composition. The interface conditions so engineered led to a low surface recombination velocity ~3000 cm/s. A direct correlation has been established between the process conditions, interfacial composition, and the electrical/photoelectrical properties of the CdTe-Hg1-xCdxTe heterostructures. The passivation layer formed by this method is shown to be suitable for the fabrication of high-performance infrared detectors |
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