title: Investigation on the passivated Si/Al2O3 interface fabricated by non-vacuum spatial atomic layer deposition system.
abstract: Currently, aluminum oxide stacked with silicon nitride (Al2O3/SiNx:H) is a promising rear passivation material for high-efficiency P-type passivated emitter and rear cell (PERC). It has been indicated that atomic layer deposition system (ALD) is much more suitable to prepare high-quality Al2O3 films than plasma-enhanced chemical vapor deposition system and other process techniques. In this study, an ultrafast, non-vacuum spatial ALD with the deposition rate of around 10 nm/min, developed by our group, is hired to deposit Al2O3 films. Upon post-annealing for the Al2O3 films, the unwanted delamination, regarded as blisters, was found by an optical microscope. This may lead to a worse contact within the Si/Al2O3 interface, deteriorating the passivation quality. Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al2O3 fabrication effectively reduce a considerable amount of blisters. The residual blisters can be further out-gassed when the Al2O3 films are thinned to 8 nm and annealed above 650°C. Eventually, the entire PERC with the improved triple-layer SiO2/Al2O3/SiNx:H stacked passivation film has an obvious gain in open-circuit voltage (V oc) and short-circuit current (J sc) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively. The electrical performance of the optimized PERC with the V oc of 0.647 V, J sc of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.
authors: Department of Materials Science and Engineering, DaYeh University, No. 168, Xuefu Road, Changhua, 515 Taiwan.
authors: Shui-Yang
authors: SY
authors: Lien
authors: Department of Electrical Engineering, National Chung Hsing University, 250 State Road, Taichung, 402 Taiwan.
authors: Chih-Hsiang
authors: CH
authors: Yang
authors: Crystalline Silicon R & D Section, Mosel Vitelic Inc, No. 1, Creation Road 1, Hsinchu, 300 Taiwan.
authors: Kuei-Ching
authors: KC
authors: Wu
authors: Department of Electrical Engineering, National Chung Hsing University, 250 State Road, Taichung, 402 Taiwan.
authors: Chung-Yuan
authors: CY
authors: Kung
keywords: Al2O3/SiNx:H stacked rear passivation; Blister; H stacked passivation films; Non-vacuum spatial atomic layer deposition; PERC; Triple-layer SiO2/Al2O3/SiNx