14.1
14
A closer look to some processes
No matter whether solar cells are to be made from crystalline wafers as discussed in
Chapter 12 or with thin-film technology as treated in Chapter 13, many processes will be
involved. In this chapter, we discuss some important processes that are used for the
fabrication of solar cells. Note that the list of processes treated in this chapter is by no
means conclusive. The content of this chapter was provided by G. Papakonstantinou and is
used with his kind permission [89].
Plasma-enhanced chemical vapour
deposition
Plasma-enhanced chemical vapour deposition (PECVD) can be employed for the growth
of thin-film silicon materials, such as amorphous silicon, nanocrystalline silicon, and
alloys such as silicon carbide or silicon oxide. The layers can be made intrinsic, n- or pdoped. PECVD allows the deposition of thin films at low operating temperatures, below
200 °C. The principal properties of these films are high quality, appropriate adhesion,
desirable coverage of textured structures and uniformity.
Figure 14.1 (a) illustrates the PECVD process. Depending on the desired material, a
mixture of different gases such as silane (SiH 4 ), methane (CH 4 ), hydrogen (H 2 ), and
carbon dioxide (CO 2 ) is introduced in an ultrahigh vacuum (UHV) reaction chamber to be
converted into glow discharge (plasma). The conversion is regulated by an oscillating
electric field between two conductive electrodes through an RF signal of 13.56 MHz or a
VHF signal of 50–80 MHz.
14
A closer look to some processes
No matter whether solar cells are to be made from crystalline wafers as discussed in
Chapter 12 or with thin-film technology as treated in Chapter 13, many processes will be
involved. In this chapter, we discuss some important processes that are used for the
fabrication of solar cells. Note that the list of processes treated in this chapter is by no
means conclusive. The content of this chapter was provided by G. Papakonstantinou and is
used with his kind permission [89].
Plasma-enhanced chemical vapour
deposition
Plasma-enhanced chemical vapour deposition (PECVD) can be employed for the growth
of thin-film silicon materials, such as amorphous silicon, nanocrystalline silicon, and
alloys such as silicon carbide or silicon oxide. The layers can be made intrinsic, n- or pdoped. PECVD allows the deposition of thin films at low operating temperatures, below
200 °C. The principal properties of these films are high quality, appropriate adhesion,
desirable coverage of textured structures and uniformity.
Figure 14.1 (a) illustrates the PECVD process. Depending on the desired material, a
mixture of different gases such as silane (SiH 4 ), methane (CH 4 ), hydrogen (H 2 ), and
carbon dioxide (CO 2 ) is introduced in an ultrahigh vacuum (UHV) reaction chamber to be
converted into glow discharge (plasma). The conversion is regulated by an oscillating
electric field between two conductive electrodes through an RF signal of 13.56 MHz or a
VHF signal of 50–80 MHz.