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Investigation of hydrogen plasma treatment for reducing defects in silicon quantum dot superlattice structure with amorphous silicon carbide matrix.

Yamada S, Kurokawa Y, Miyajima S, Konagai M - Nanoscale Res Lett (2014)

Bottom Line: We investigate the effects of hydrogen plasma treatment (HPT) on the properties of silicon quantum dot superlattice films.The total dangling bond density decreases from 1.1 × 1019 cm-3 to 3.7 × 1017 cm-3, which is comparable to the defect density of typical hydrogenated amorphous silicon carbide films.A damaged layer is found to form on the surface by HPT; this layer can be easily removed by reactive ion etching.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physical Electronics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan. yamada.s.aj@m.titech.ac.jp.

ABSTRACT
We investigate the effects of hydrogen plasma treatment (HPT) on the properties of silicon quantum dot superlattice films. Hydrogen introduced in the films efficiently passivates silicon and carbon dangling bonds at a treatment temperature of approximately 400°C. The total dangling bond density decreases from 1.1 × 1019 cm-3 to 3.7 × 1017 cm-3, which is comparable to the defect density of typical hydrogenated amorphous silicon carbide films. A damaged layer is found to form on the surface by HPT; this layer can be easily removed by reactive ion etching.

No MeSH data available.


Spin densities of Si-QDSLs after a 60-min HPT.
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Figure 3: Spin densities of Si-QDSLs after a 60-min HPT.

Mentions: NTotal-DB, NSi-DB, and NC-DB for several treatment temperatures are shown in Figure 3. Post-HPT, Si-QDSL defect density (1.1 × 1019 cm-3) clearly reduced compared with the defect density before HPT. The defect density for 200°C treatment is still high because hydrogen diffusion is insufficient. Hydrogen intrusion depth for 60-min HPT can be estimated to be below 100 nm, and a several dangling bonds remain in the deep area of the film. The defect density for 300°C treatment is lower than that at 200°C. A large amount of hydrogen reaches the interface of the film and substrate during the 60-min HPT. The measured g value in this sample was 2.00275, which is quite similar to the g value of C-DB, meaning that NSi-DB is less than NC-DB. Based on Equation 5, NSi-DB is estimated to be 2.2 × 1016 cm-3, indicating that Si-DBs can be efficiently passivated by the incorporated hydrogen. For the 400°C treatment, defect density decreases to 3.7 × 1017 cm-3, which is comparable with the defect density of an a-SiC film. The g value for 400°C treatment was higher than that for 300°C treatment, indicating that C-DBs - which are dominant in the total-DBs - significantly decrease despite the increment in Si-DBs. For the 500°C treatment, defect density increases despite efficient hydrogen incorporation in the Si-QDSL, showing that the hydrogen atoms are thermally activated from the Si-H bond state to the interstitial state above 300°C and from the C-H bond state to the interstitial state above 400°C. These temperatures mostly correspond to the temperatures of dehydrogenation from Si-H bonds and C-H bonds, which are approximately above 300°C [26] and 450°C to 550°C [27], respectively. In the 500°C treatment sample, a large amount of hydrogen atoms were in the interstitial sites; they did not contribute to the passivation of the dangling bonds.


Investigation of hydrogen plasma treatment for reducing defects in silicon quantum dot superlattice structure with amorphous silicon carbide matrix.

Yamada S, Kurokawa Y, Miyajima S, Konagai M - Nanoscale Res Lett (2014)

Spin densities of Si-QDSLs after a 60-min HPT.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3926976&req=5

Figure 3: Spin densities of Si-QDSLs after a 60-min HPT.
Mentions: NTotal-DB, NSi-DB, and NC-DB for several treatment temperatures are shown in Figure 3. Post-HPT, Si-QDSL defect density (1.1 × 1019 cm-3) clearly reduced compared with the defect density before HPT. The defect density for 200°C treatment is still high because hydrogen diffusion is insufficient. Hydrogen intrusion depth for 60-min HPT can be estimated to be below 100 nm, and a several dangling bonds remain in the deep area of the film. The defect density for 300°C treatment is lower than that at 200°C. A large amount of hydrogen reaches the interface of the film and substrate during the 60-min HPT. The measured g value in this sample was 2.00275, which is quite similar to the g value of C-DB, meaning that NSi-DB is less than NC-DB. Based on Equation 5, NSi-DB is estimated to be 2.2 × 1016 cm-3, indicating that Si-DBs can be efficiently passivated by the incorporated hydrogen. For the 400°C treatment, defect density decreases to 3.7 × 1017 cm-3, which is comparable with the defect density of an a-SiC film. The g value for 400°C treatment was higher than that for 300°C treatment, indicating that C-DBs - which are dominant in the total-DBs - significantly decrease despite the increment in Si-DBs. For the 500°C treatment, defect density increases despite efficient hydrogen incorporation in the Si-QDSL, showing that the hydrogen atoms are thermally activated from the Si-H bond state to the interstitial state above 300°C and from the C-H bond state to the interstitial state above 400°C. These temperatures mostly correspond to the temperatures of dehydrogenation from Si-H bonds and C-H bonds, which are approximately above 300°C [26] and 450°C to 550°C [27], respectively. In the 500°C treatment sample, a large amount of hydrogen atoms were in the interstitial sites; they did not contribute to the passivation of the dangling bonds.

Bottom Line: We investigate the effects of hydrogen plasma treatment (HPT) on the properties of silicon quantum dot superlattice films.The total dangling bond density decreases from 1.1 × 1019 cm-3 to 3.7 × 1017 cm-3, which is comparable to the defect density of typical hydrogenated amorphous silicon carbide films.A damaged layer is found to form on the surface by HPT; this layer can be easily removed by reactive ion etching.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physical Electronics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8552, Japan. yamada.s.aj@m.titech.ac.jp.

ABSTRACT
We investigate the effects of hydrogen plasma treatment (HPT) on the properties of silicon quantum dot superlattice films. Hydrogen introduced in the films efficiently passivates silicon and carbon dangling bonds at a treatment temperature of approximately 400°C. The total dangling bond density decreases from 1.1 × 1019 cm-3 to 3.7 × 1017 cm-3, which is comparable to the defect density of typical hydrogenated amorphous silicon carbide films. A damaged layer is found to form on the surface by HPT; this layer can be easily removed by reactive ion etching.

No MeSH data available.