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Title:	Study on interface stability of Mo/CdTe heterojunction in thin film solar cell
Authors:	Nripen Dhar (P63149)
Keywords:	Interface stability Solar cells
Issue Date:	2014
Description:	One of the vital parts for Cadmium Telluride (CdTe) based solar cell, that is metal-semiconductor (MS) junction between Mo and CdTe was investigated on different substrates (soda lime glass, Molybdenum sheet, polyimide). Numerical modelling on the effects of the presumed interlayer formation between CdTe and Mo back contact on the overall performance is carried out by using Analysis of Microelectronic and Photonic Structures (AMPS-1D) software. It was found that the cell performance decreased as the electron affinity changed. The increase in MoTe2 bandgap results in unfavourable effect to the performance of the cell. However, the increase of the carrier concentration improves the cell performance. In practical fabrication, both Mo and CdTe films were deposited by RF magnetron sputtering. X-Ray diffraction patterns of Mo/CdTe films on soda lime glass (SLG) revealed CdTe (111) and Mo (110) as well as (211) crystal planes for different deposition time of CdTe (e.g. 2-15 minutes). Moreover, Mo/CdTe films on polyimide (PI) substrate shows a strong preferential orientation of MoTe2 in (100) at 2ϴ=29.44˚, which becomes less apparent as deposition time of CdTe increases. Energy-dispersive X-ray (EDX) measurement finds that concentration signal from Mo and concentration signal from Te interact with each other and signal concentration from Cd becomes zero at some positions inside the film. For 2 minutes deposition time of CdTe, bulk concentration for Mo/CdTe films on polyimide (PI) substrate was found to be 1.1 x 1018 cm-3 to 1.42 x 1018 cm-3, which is almost equal to MoTe2. Furthermore, for the highest deposition time on PI substrate the range became 8.1 x 1016 cm-3 to 9.01 x 1016 cm-3, which is nearly equal to CdTe. The type of MoTe2 on PI substrate was found to be n-type, which is an indication of forming double diode on PI substrate. In conclusion, this study has investigated the metal-semiconductor junction of Mo/CdTe thin films on different substrates in terms of theoretical and practical investigation. An unintentional interlayer of MoTe2 forms in between Mo and CdTe for substrate configuration, which depends on substrate types. Interestingly, the formed MoTe2 is found to be n-type in nature and causes double diode formation on flexible PI substrate that induces high series resistance. This may be one of the main reasons for lower efficiency on PI substrate compare to glass base substrate for substrate configuration, as found from this fundamental study.,Master/Sarjana
Pages:	164
Call Number:	TK7872.T55D484 2014 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Solar Energy Research Institute / Institut Penyelidikan Tenaga Suria (SERI)

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