Effect of CdCl2 annealing treatment on interdiffusion  and reaction at the CdS/CdTe interface

HOU Zerong; WAN Lei; BAI Zhizhong; WANG Deliang

doi:10.3969/j.issn.0253-2778.2010.07.010

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Effect of CdCl2 annealing treatment on interdiffusion and reaction at the CdS/CdTe interface

Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China

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https://doi.org/10.3969/j.issn.0253-2778.2010.07.010

Received Date: 22 January 2010
Rev Recd Date: 12 April 2010
Publish Date: 31 July 2010

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Abstract

Abstract

A structure of Glass/FTO/CdS/CdTe/CdS based on the CdTe solar cell (Glass/FTO/CdS/CdTe) was adopted to study the effect of CdCl2 annealing treatment on the interdiffusion and the related reaction at the CdS/CdTe interface. Investigations show that surface morphology changs dramatically under different annealing treatment temperatures. The crystal size of CdS increases from 20 nm to 70 nm between 300～350 ℃. This temperature range is consistent with that of the CdS sphalerite to wurtzite phase transformation. CdS/CdTe interdiffusion happens at around 350 ℃, and CdS0.85Te0.15 with hexagonal-wurtzite structure is detected at 550 ℃. The CdS is quickly consumed up through interdiffusion with CdTe and forming CdSxTe1-x alloy. CdTeO3 begins to form at 450℃. Raman scattering shows that the intensity of CdS 1LO peak decreases from 350 ℃ and shifts to lower frequency, which reveals the formation of CdSxTe1-x. The XPS spectrum of samples confirms the formation of CdSxTe1-x and CdTeO3. CdCl2 protects CdS/CdTe from oxidation and promotes interdiffusion at the interface and formation of CdSxTe1-x during air annealing.

Abstract

A structure of Glass/FTO/CdS/CdTe/CdS based on the CdTe solar cell (Glass/FTO/CdS/CdTe) was adopted to study the effect of CdCl2 annealing treatment on the interdiffusion and the related reaction at the CdS/CdTe interface. Investigations show that surface morphology changs dramatically under different annealing treatment temperatures. The crystal size of CdS increases from 20 nm to 70 nm between 300～350 ℃. This temperature range is consistent with that of the CdS sphalerite to wurtzite phase transformation. CdS/CdTe interdiffusion happens at around 350 ℃, and CdS0.85Te0.15 with hexagonal-wurtzite structure is detected at 550 ℃. The CdS is quickly consumed up through interdiffusion with CdTe and forming CdSxTe1-x alloy. CdTeO3 begins to form at 450℃. Raman scattering shows that the intensity of CdS 1LO peak decreases from 350 ℃ and shifts to lower frequency, which reveals the formation of CdSxTe1-x. The XPS spectrum of samples confirms the formation of CdSxTe1-x and CdTeO3. CdCl2 protects CdS/CdTe from oxidation and promotes interdiffusion at the interface and formation of CdSxTe1-x during air annealing.