Investigation of Plasma Deposited Boron Phosphide and Its Contact to Silicon

• Published in: ACS applied energy materials 2022-05, Vol.5 (5), p.5367-5373
• Main Authors: Maksimova, Alina A., Uvarov, Alexander V., Baranov, Artem I., Gudovskikh, Alexander S., Kudryashov, Dmitri A., Vyacheslavova, Ekaterina A., Morozov, Ivan A., Le Gall, Sylvain, Kleider, Jean-Paul
• Format: Article
• Language: English
• Subjects: Engineering Sciences; Materials; Micro and nanotechnologies; Microelectronics
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.1c02704

Boron phosphide layers were fabricated using plasma enhanced chemical vapor deposition and modified atomic layer deposition methods with trimethylboron (TMB) and phosphine (PH3) precursors, and electrical contact properties to silicon were investigated. The presence of boron and phosphorus was proved by energy dispersive X-ray spectroscopy and secondary ion mass spectrometry. Influence of the deposition parameters on characteristics of the layers and on the silicon substrate was studied. The band gap of boron phosphide was evaluated by optical measurements at 2.1–2.2 eV. In Au/BP/Si structures, capacitance measurements revealed the presence of electron accumulation at the BP/Si interface. This regime can be explained by lowly doped or undoped BP and Fermi level pinning at the BP/Si interface due to the presence of interface defect states. We also used the deep level transient spectroscopy method from which were detected defects in the near-surface silicon region that may be formed under the influence of high-power plasma during the deposition of the boron phosphide layer. However, insertion of a thin i-a-Si:H layer between BP and Si acts as a passivating layer, thus allowing one to decrease the interface state density and increase the minority carrier lifetime and open-circuit voltage, which is promising for photovoltaic applications.