Title :
Hydrogenated Amorphous Carbon-Silicon Alloys [a-SixC1-x(n):Hy] used as Emitters of Heterojunction Solar Cells
Author :
Mueller, Thomas ; Scherff, Maximilian ; Düngen, Wolfgang ; Ma, Yue ; Fahrner, Wolfgang R.
Author_Institution :
Univ. of Hagen
Abstract :
This work focuses on hydrogenated amorphous carbon-silicon alloys [a-SixC1-x(n):Hy] used as emitters of heterojunction solar cells. The a-SixC1-x(n):Hy alloys are deposited on p-type silicon (100) substrates via plasma enhanced chemical vapor deposition (PECVD) using a gas mixture of silane (SiH4), phosphine (PH3), methane and hydrogen (CH4), respectively. For characterization of the heterojunction solar cells, produced as mentioned above, I-V measurements, spectral response and reflection measurements as well as spectroscopic ellipsometry (SE) have been applied. Particularly, we focused on several effects, such as widening of the optical band gap of the emitter within the a-Six C1-x(n):Hy film, the thickness of the emitter and the I-V characteristics of the solar cell. It was confirmed that the band gap EG can be tailored by using an appropriate gas mixture during the decomposition. The optical band gap as well as the thickness of the emitter were determined by spectroscopic ellipsometry. The investigations have shown that the band gap increases with increasing carbon and hydrogen concentration in the feed stock during deposition. Although the addition of carbon (C) degrades the photoelectronic properties in the emitter layer, this deterioration can be minimized by H dilution. We will show that the efficiency of the prepared heterojunction solar cells can be improved with an appropriate addition of carbon and hydrogen in the emitter layer
Keywords :
amorphous semiconductors; decomposition; ellipsometry; energy gap; hydrogen; plasma CVD; semiconductor heterojunctions; semiconductor thin films; silicon compounds; solar cells; wide band gap semiconductors; I-V measurements; PECVD; SixC1-x:Hy; decomposition; emitter layer; heterojunction solar cells; hydrogenated amorphous carbon-silicon alloys; methane; optical band gap; phosphine; photoelectronic properties; plasma enhanced chemical vapor deposition; silane; spectroscopic ellipsometry; Amorphous materials; Carbon dioxide; Ellipsometry; Heterojunctions; Hydrogen; Optical films; Photonic band gap; Photovoltaic cells; Plasma measurements; Spectroscopy;
Conference_Titel :
Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on
Conference_Location :
Waikoloa, HI
Print_ISBN :
1-4244-0016-3
Electronic_ISBN :
1-4244-0017-1
DOI :
10.1109/WCPEC.2006.279715