Photoelectrochemical Studies and Capacitance Measurements during the Nitride Passivation of InP in Liquid Ammonia (-55°C)

Tuesday, 26 May 2015: 12:00
Conference Room 4F (Hilton Chicago)
C. Njel (Institut lavoisier de Versailles, UVSQ), I. Bakas (Institut Lavoisier de Versailles, UVSQ), D. Aureau (Institut Lavoisier de Versailles), A. M. Gonçalves, and A. Etcheberry (Institut Lavoisier de Versailles, UVSQ)
This work presents a fundamental photo-electrochemical process at the interface SC/electrolyte. The photoelectrochemical passivation of n-InP is reported in liquid ammonia (‑55 °C) during an anodic treatment[1]. The extraction of InP sample from the solvent is successfully performed at ambient temperature. Thanks to XPS (X-ray Photoelectron Spectroscopy), a reproducible polyphosphazene like film is reported on InP (‑[(H2N)‑P=N]n‑)[2]. A soft anodic electrochemical treatment under illumination is applied at the interface to provide a gradual controlled coverage ratio of the surface by the film. This quantitative study requires a chronopotentiometry process with a constant anodic current of 1µA.cm-2 under illumination. An anodic charge around 0.3 mC.cm-2 is enough to ensure a complete coverage of the surface by the film. According to the anodic charge a gradual striking flat band potential shift is observed (Fig. 1). A flat C‑2 = f(V) is extended over 1 volt leading to a high interfacial capacitance (» 2µF.cm-2). From the analysis of capacitance‑potential curves, the interface appears to be under accumulation conditions after the film formation. A significant drop of the resulting photo potential is then observed (Fig. 2). However, under a strong positive overvoltage (» 1V), a stationary anodic photocurrent is recovered.

[1] A-M. Gonçalves, N. Mézailles, C. Mathieu, P. Le Floch, A. Etcheberry, « «Fully Protective yet functionalizable monolayer onto InP” Chemistry of Materials.22(2010) 3114-3120.


[2] A-M. Gonçalves, C.Njel, C. Mathieu, D.Aureau, A. Etcheberry. « Phosphazene like film formation on InP in liquid ammonia (223K)  . Thin Solid Films 538 (2013) 21–24.