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Computer analysis of the role of p -layer quality, thickness, transport mechanisms, and contact barrier height in the performance of hydrogenated amorphous silicon p - i - n solar cells

1991; American Institute of Physics; Volume: 69; Issue: 10 Linguagem: Inglês

10.1063/1.347645

1520-8850

J. K. Arch, F.A. Rubinelli, Jingya Hou, Stephen J. Fonash,

Advancements in Semiconductor Devices and Circuit Design

The transport simulations provided by the computer program AMPS have been used to give an in-depth analysis of the role of the p-layer contact barrier height, contact transport mechanism, p-layer thickness, and p-layer quality on the performance of hydrogenated amorphous silicon p-i-n solar cells. We demonstrate for the first time that, if the contact barrier height to the p-layer is below a critical value and if tunneling through the p-layer is not important, then the performance of cells with either active or dead p-layers varies with contact barrier height regardless of p-layer thickness. We show that, even for an optimistic p-layer active doping density of 1019 cm−3, this critical barrier height is high (∼1.2 eV). Our analysis implies that one of two situations must occur in an actual a-Si:H p-i-n structure: the p-layer contact plays an important role in determining cell efficiency, or the tunneling of holes through the front contact/p-layer interface must be important. Comparison of simulated results, with and without tunneling, with experimental data suggests that tunneling is occurring in actual devices and is important in efficient structures.