Paper
Quantitative Analyses of Negative Interface Trapped Charge in p-Type Si Wafer Studied by Frequency-Dependent Alternating Current Surface Photovoltage Technique
- Authors:
- Hirofumi Shimizu
- Abstract
- The conventionally defined oxide charge (Qo) in thermally oxidized p-type Si(001) wafers is investigated by the frequency-dependent alternating current (AC) surface photovoltage (SPV). Upon etching the oxide layer, a minimum AC SPV was observed nearby SiO2–Si interface. The reduction of AC SPV indicates the appearance of a negative charge. This strongly suggests that a fixed oxide charge (Qf) and oxide trapped charge (Qot) might have been etched off. Then, the possible charge must be Qit which is located to be approximately 2.7 nm from the SiO2-Si interface. This explains that Qf may be situated farther than Qit from the SiO2-Si interface. The Qit density (Dit) is calculated to be 9x1010 cm2・eV-1 by analysing the AC SPV vs frequency relationship which is in good agreement with the previous result. The HF solution-etched p-type Si surface can be positive possibly because Si dangling bonds capture holes from p-type Si substrate. This positive charge may not have the same characteristic as positive Qf. It is because Qf is stable in air exposure at room temperature, in contrast, the positive charge on HF solution-dipped p-type Si surface decreases gradually with air exposure time in the measurements of frequency-dependent AC SPV as previously reported.
- Keywords
- Si; Oxidation; Fixed Oxide Charge; Interface Trapped Charge; Surface Photovoltage
- StartPage
- 49
- EndPage
- 51
- Doi