In situ ellipsometric study of the influence of powder formation on the initial growth of glow discharge a− Si: H

• Published in: Thin solid films 1993-01, Vol.233 (1), p.297-300
• Main Authors: Schmidt, U.I., Schröder, B., Oechsner, H.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Physics; Solid surfaces and solid-solid interfaces; Surface and interface dynamics and vibrations; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(93)90112-3

Even under standard preparation conditions for amorphous hydrogenated silicon ( a− Si: H) by r.f. glow discharge decomposition of silane, powder formation can occur leading to an initial transient behaviour of silane discharges. Phase-modulated real-time in situ ellipsometry is used to study the influence of the discharge behaviour on the initial stage of growth of a− Si: H after ignition and subsequent to intentional discharge interruptions. A clear correlation between the powder-determined time dependences of the discharge parameters pressure and self-bias voltage and of the ellipsometric angles is confirmed. In the discharge regime where this initial transient behaviour due to powder formation is observed, the corresponding Δ - ψ trajectories can be attributed to the initial growth of less dense material. The time-dependent Δ signal of the growing film is found to be very sensitive even to minor discharge perturbations. The influence of controlled temporal variations of preparation parameters on the growing a− Si: H film can be simultaneously monitored by real-time in situ ellipsometry. This offers an opportunity for interface optimization in a− Si: H structures.