Characteristics of in0.7Ga0.3as MOS capacitors obtained using hydrochloric acid treatment, ammonium sulfide passivation, methanol treatment, and forming gas annealing

Sheng Ti Chung, Yi Chin Huang, Yen Chun Fu, Yao Jen Lee, Tien-Sheng Chao

Research output: Contribution to journalArticle

Abstract

This paper proposes a chemical pre-treatment process to reduce sulfate prior to atomic layer deposition of Al2O3 gate dielectrics on n-doped In0.7Ga0.3As layers to form metal oxide semiconductor capacitors (MOSCAPs). Cleaning with methanol was done after hydrogen chloride etching and ammonium sulfide passivation. X-ray photoelectron spectroscopy performed on the sample with methanol cleaning indicated that its native oxide regrowth was effectively prevented on the sulfur-passivated In0.7Ga0.3As surface under air exposure. By analysis using atomic force microscopy of the sample cleaned using methanol, no further increase of surface roughness was observed after 5 months of air exposure. In addition, a mid-gap interface defect density (Dit) of 1.3 × 1012 cm−2 eV−1 was obtained from this sample. After forming gas annealing (FGA), the Dit was improved significantly, to a value below 1012 cm−2 eV−1. The obtained data indicate that the combination of chemical pre-treatment and FGA is advantageous to passivating the trap states on In0.7Ga0.3As MOSCAPs.

Original languageEnglish
Pages (from-to)P457-P463
JournalECS Journal of Solid State Science and Technology
Volume8
Issue number9
DOIs
StatePublished - 1 Jan 2019

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