Boron contamination in the intrinsic layers of amorphous silicon solar cells

摘要

The undoped hydrogenated amorphous silicon (a‐Si:H) is well‐known to be n- type. When this material is used to fabricate nip solar cells in a single chamber system, it tends to be contaminated by the residue dopants remaining from the deposition of the first boron‐doped p layer unless adequate precautions are taken. The photoresponses of the indium tin oxide (ITO)ip a‐Si:H:F/stainless steel solar cells were measured by using band‐passed blue (350 ≪λ≪500 nm) and red (λ≫580 nm) light. The blue light penetrates only about 1400 Å deep into the device whereas the red light is absorbed rather uniformly inside a typical 4000‐Å‐thick cell. These two responses as a function of applied biases can thus be used to find out the location of the carrier collection region which in turn tells us the degree of contamination in the i layer. Several examples will be discussed which illustrate the close relationships between the deposition parameters and the cell performances.