ChemInform Abstract: Compositional Analysis of Electrosynthesized Semiconductor Thin Films by Electrochemical Quartz Crystal Microgravimetry: Application to the Cd + Se System.

Abstract

Group II-VI compound semiconductors such as CdSe are important in a wide spectrum of optoelectronic applications [l]. As reviewed elsewhere [l], electrodeposition is a simple and versatile method for preparing thin films of these materials. However, contamination of the target material with side-products (e.g. CdSe with Se) is often a problem with the electrodeposition technique. The defect chemistry of II-VI compound semiconductors (i.e. whether they are nor p-type) is also critically dependent on their non-stoichiometry, e.g. the Cd: Se ratio. Thus there clearly is a need to identify and evaluate new techniques for the in situ compositional analysis of semiconductor thin films. In this report, we wish to describe the use of electrochemical quartz-crystal microgravimetry (EQCM) for this purpose. The use of EQCM has rapidly grown in recent years with reviews available [2,3]. An earlier paper from this laboratory described a study of aqueous Te electrochemistry using combined voltammetry, coulometry and microgravimetry [41. The new experiments described below on the model Cd + Se system demonstrate, we believe for the first time, that it is possible to establish in situ compositional profiles for electrosynthesized thin films using a combination of stripping with the EQCM technique.