Abstract
We describe experimental and theoretical studies to determine the effects of phosphorous as a passivating agent for the SiO 2/4H-SiC interface. Annealing in a P 2O 5 ambient converts the SiO 2 layer to PSG (phosphosilicate glass) which is known to be a polar material. Higher mobility (approximately twice the value of 30-40 cm 2/V s obtained using nitrogen introduced with an anneal in nitric oxide) and lower threshold voltage are compatible with a lower interface defect density. Trap density, current-voltage and bias-temperature stress (BTS) measurements for MOS capacitors are also discussed. The BTS measurements point to the possibility of an unstable MOSFET threshold voltage caused by PSG polarization charge at the O-S interface. Theoretical considerations suggest that threefold carbon atoms at the interface can be passivated by phosphorous which leads to a lower interface trap density and a higher effective mobility for electrons in the channel. The roles of phosphorous in the passivation of correlated carbon dangling bonds, for SiC counter-doping, for interface band-tail state suppression, for Na-like impurity band formation and for substrate trap passivation are also discussed briefly.
Original language | English |
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Pages (from-to) | 103-107 |
Number of pages | 5 |
Journal | Solid-State Electronics |
Volume | 68 |
DOIs | |
Publication status | Published - Feb 1 2012 |
Keywords
- Channel mobility
- Interface trap density
- Phosphorous
- Threshold voltage stability
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry