Catalytic doping of phosphorus and boron atoms on hydrogenated amorphous silicon films

Abstract

We investigate the low-temperature doping of phosphorus (P) and boron (B) atoms on hydrogenated amorphous silicon (a-Si:H) films by catalytic doping (Cat-doping). The conductivity of a-Si:H films increases as catalyzer temperature (T cat) increases, and the increase in conductivity is accompanied by a significant reduction in activation energy obtained from the Arrhenius plot of the conductivity. Secondary ion mass spectrometry (SIMS) measurement reveals that Cat-doped P and B atoms exist within ∼10–15 nm from the a-Si:H film surface, indicating that the shallow doping of P and B atoms is realized on a-Si:H films similarly to the case of Cat-doping on crystalline Si (c-Si) wafers. We also confirm no additional film deposition during Cat-doping. These results suggest that decomposed species are effectively doped on a-Si:H films similarly to the case of Cat-doping on c-Si.

Phosphorous Catalytic‐Doping of Silicon Alloys for the Use in Silicon Heterojunction Solar Cells

“…The SIMS results show that the incorporation of P atoms into films is different in the three silicon alloy films. In the work of Matsumura et al, [10,11] it was already shown that from catdoping, P atoms have larger doping depth in a-Si:H than that in c-Si. The different profiles of three silicon alloys might also come from the different microstructures and compositions of these three silicon alloys.…”

“…During a cat-doping process, the gas molecules decompose at the hot surface of the catalyzing wires, then the decomposed radicals diffuse radially toward the sample and penetrate into the surface of the silicon films forming a shallow depth doping layer with a thickness of 5-15 nm. [10,11] With catdoping, material properties, e.g., conductivity and doping concentration, can be tuned beyond the level which is achievable for as-grown films. [11,12] Especially for materials, where the conductivity is limited upward due to restrictions from process boundary conditions during film depositions or from trade-off with other device relevant material properties, the cat-doping process might be beneficial to overcome the limit or find better trade-off regime.…”

“…So far, cat-doping has been studied mainly on crystalline silicon, amorphous silicon, and microcrystalline silicon. [10,11,13,14] Former studies have shown that cat-doping can improve the conductivity of a-Si:H and μc-Si:H films. Cat-doping can also improve the passivation quality of the passivated samples with symmetric structures of μc-Si:H(n)/a-Si:H(i)/c-Si/a-Si:H(i)/ μc-Si:H(n) and a-Si:H(n)/a-Si:H(i)/c-Si/a-Si:H(i)/a-Si:H(n) in which the interfaces of μc-Si:H(n) and c-Si are cat-doped, respectively.…”

Hot metal wires as sinks and sources of B atoms

“…decomposing B 2 H 6 on hot W wire surfaces [18][19][20]. The problem is that B 2 H 6 is not only toxic, but also explosive.…”

Phosphorus Catalytic Doping on Intrinsic Silicon Thin Films for the Application in Silicon Heterojunction Solar Cells

“…Doping gases, such as phosphine (PH 3 ) and diborane (B 2 H 6 ), are catalytically decomposed at the hot surface of the filaments into phosphorous (P) and boron (B) radicals. , The radicals move from the filament surface to the sample surface and then diffuse into the silicon material films, forming a shallow depth doping layer with a thickness of 5–20 nm. − Therefore, it is possible to replace the deposition of the doped silicon layer by Cat-doping on the intrinsic layer, which reduces the parasitic absorption of doped silicon layers. Former studies have shown that the material properties, such as conductivity and doping concentration, can be further tuned beyond the level that is achievable for as-grown films. ,, It has also been reported that the passivation quality of SHJ structures could be improved with Cat-doping on different interfaces, such as at the c-Si, a-Si:H­(i), and doped silicon layer surfaces in a SHJ structure. ,,,− …”