Investigation of silicon surface passivation by sputtered amorphous silicon and thermally evaporated molybdenum oxide films using temperature- and injection-dependent lifetime spectroscopy. (21st October 2020)

• Record Type: Journal Article
• Authors: Singh, Krishna; Nayak, Mrutyunjay; Singh, Sonpal; Komarala, Vamsi K
• Is Part Of: Semiconductor science and technology. Volume 35:Number 12(2020)
• Publication Date: 2020-10-21
• Subjects: silicon -- surface passivation -- sputtering -- MoOx -- lifetime spectroscopy -- amorphous silicon; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/abb2b4
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: Crystalline silicon (c-Si) surface passivation has been investigated by sputtered hydrogenated intrinsic amorphous silicon (S-i-a-Si:H) and thermally evaporated molybdenum oxide (MoOx ) thin films. The temperature- and injection-dependent lifetime spectroscopy technique has been adopted for analyzing the passivation quality of the c-Si surface, using parameters such as the minority carrier effective lifetime (τeff ), the activation energy of surface/interface defect states (Δ E ), and the electron to hole carrier capture cross-section ratio ( k ) at the interface. With S-i-a-Si:H films, a τeff of ∼70 µ s and Δ E of ∼51 meV have been observed in comparison to a τeff of ∼110 µ s and Δ E of ∼109 meV from the MoOx films. These entirely different parameters are an indication of the relatively strong carrier recombination with dense interface/surface states from the S-i-a-Si:H passivation layers. The S-i-a-Si:H layers are unable to minimize the c-Si surface trap states with the chemical passivation for reducing carrier recombination due to the generation of additional surface defect states by the sputtering damage. However, the MoOx layers show better c-Si surface passivation due to the reduction of majority carriers by the carrier inversion (field-effect passivation) and chemical passivation. This effect is clearly reflected with the opposite trend in the carrier capture analysis from S-i-a-Si:H and MoOx layers.