Highly conductive and wide band gap amorphous-microcrystalline mixed-phase silicon films prepared by photochemical vapor deposition

Abstract

Doped hydrogenated amorphous-microcrystalline mixed-phase silicon (μc-Si:H) films were prepared by the mercury photosensitized decomposition of a disilane-hydrogen gas mixture, by adding phosphine and diborane for n and p type, respectively. The maximum dark conductivity and optical band gap of the films were, respectively, 20 S cm−1 and ∼2.0 eV for n type, and 1 S cm−1 and 2.3 eV for p type. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced up to 70 for n type, and even 300 for p type, to obtain such a highly conductive and wide gap film. The crystallinity of the photodeposited μc-Si films appeared to be improved in comparison with that of films by conventional plasma glow discharge technique.

Post hydrogenation effect by hot wire method on poly-crystalline silicon based devices

“…Several techniques for low-temperature deposition of poly-Si have been intensively investigated like, e.g. magnetron sputtering [1], plasma enhanced chemical vapor deposition (PECVD) [2], hot-wire CVD (HW-CVD) [3], and photo-CVD [4]. These techniques, however, are not fully mature yet and several problems need to be solved.…”

Nanocomposite Thin Films for Solar Energy Conversion

“…In the early stage, the nc-Si:H materials showed an n-type character with the Fermi energy level close to the conduction band edge, which is probably due to unintentionally incorporated impurities such as oxygen. Therefore, nc-Si:H was first used as doped layers by adding phosphorus for n layer or boron for p layer [33,34]. Using nc-Si:H-doped layers, especially ncSi:H p layer, has significantly increased the open-circuit voltage of a-Si:H solar cells and reduced the loss at the tunnel-junction in multi-junction cell structures [23,34].…”

Field-effect a-Si:H solar cells with transparent conductive oxide comb-shaped electrodes

“…In a pin junction a-Si:H solar cell, a considerable portion of the photogenerated carriers recombines in the doped window layer immediately and makes no contribution to the output current. To reduce photo-absorption and carrier generation in the doped layer, wide bandgap materials with low photo-absorption coefficients for visible wavelengths, such as silicon carbide (SiC), have been used as window layers [3][4][5][6]. Although the wide bandgap window layers improve cell performance, the problems of boron diffusion in undoped a-Si:H and photo-induced defects remain unsolved [7][8][9][10].…”