NMR Detection of SiH2 in Amorphous Silicon.
Abstract
NMR detection of SiH2 in hydrogenated amorphous silicon is known to be difficult due to the strong dipolar coupling between the protons of SiH2 and their neighbor protons. We have developed a new dipolar filtering technique using the Jeener-Broekaert (JB) three pulse sequence: 90_x-τ-α_y-τ_1-β_y-τ-echo. Protons from different environments (e.g., clustered hydrogen, less clustered hydrogen, SiH_2, o-H_2) respond to the JB sequence differently by showing different spin-spin relaxation time (T_2), dipolar relaxation time (T_1d), and angular dependence (α , β). Using these differences as filters, we were able to suppress the signals other than that from SiH2 and resolve the SiH2 signal up to 220 K in an amorphous silicon sample with 14 atomic percent hydrogen concentration.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1997
- Bibcode:
- 1997APS..MAR..C704C