Cavity ring down detection of SiH3 on the broadband (A)over-tilde (2)A '(1) <- (X)over-tilde (2)A(1) transition in a remote Ar-H-2-SiH4 plasma

Here we report on the use of the cavity ring down (CRD) technique for the d etection of the silyl radical SiH3 on the broadband (A) over tilde (2)A(1)' <-- (X) over tilde (2)A(1) transition around 215 nm. SiH3 has been detecte d in a remote Ar-H-2-SiH4 plasma during hydrogenated amorphous silicon (a-S i:H) thin film growth. The measurements demonstrate the capability of CRD t o measure small broadband absorptions in the deep UV in the hostile environ ment of a deposition plasma. The SiH3 absorption shows an expected dependen ce on the SiH4 precursor flow and correlates well with the a-SiH growth rat e. The observed absorptions correspond with SiH3 densities in the range 2-1 3 x 10(18) m(-3), which is at least two orders of magnitude above the estim ated SiH3 detection limit. (C) 2000 Elsevier Science B.V. All rights reserv ed.