Improved Si/SiO x interface passivation by ultra-thin tunneling oxide layers prepared by rapid thermal oxidation

• Published in: Applied surface science Vol. 353; pp. 1269 - 1276
• Main Authors: Gad, Karim M, Vossing, Daniel, Balamou, Patrice, Hiller, Daniel, Stegemann, Bert, Angermann, Heike, Kasemann, Martin
• Format: Journal Article
• Language: English
• Published: 30.10.2015
• Subjects: Annealing; Density; Electric potential; Forming; Oxidation; Passivation; Reduction; Silicon
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2015.07.060

We analyze the influence of different oxidation methods on the chemical passivation quality of silicon oxide-nanolayers on crystalline silicon wafers with surface photo voltage and quasi-steady-state photo conductance measurements. We present a simple method by means of rapid thermal oxidation (RTO) and subsequent annealing in forming gas, which requires no complex surface pre-treatment or surface pre-conditioning after cleaning. This technique allows a reproducible preparation of high-quality ultra-thin oxide-nanolayers (1.3-1.6nm) with a nearly intrinsic energetic distribution of interface states and a defect density of states of only 11012 cm-2 eV-1 at the minimum of the distribution. These results are compared with silicon oxide-nanolayers prepared by wet chemical oxidation and plasma oxidation where only a slight reduction of the interface defect density is achieved by subsequent anneal in forming gas environment. Furthermore, it is shown that applying the RTO oxide-nanolayer as an intermediate layer between Si and an a-SiNx:H layer, leads to a significant improvement of the surface passivation quality.