Sources of ultraviolet light and systems for its shaping for photoelectrical investigation of semiconductor structures

Photoelectric method is one of the most precise methods for measuring parameters of semiconductor structures, e. g., contact potential difference or potential barrier high for internal photoemission. Those parameters determine such important MOS transistor parameter like the threshold voltage VT or the flatband voltage VFB. Application of the photoemission phenomenon requires effective utilisation of the light source's energy and focusing it on the surface of a small structure. This paper discusses the issues related to the construction of an illumination system for photoelectric tests of semiconductor structures for ultraviolet light range. Light sources as well as systems for radiation shaping were described. Additionally, advantages and disadvantages of mirror and lenses systems, possibility of correcting certain aberrations and obtaining appropriate frontal distance required for introducing micromanipulators with measurement needles were discussed. Information included in this paper had a major impact on the construction of the multitask system for photoelectric tests of semiconductor structures, the authors of which received the title Technology Master - Warsaw 2001 (Mistrz Techniki - Warszawa 2001) and the first level award of the Polish Federation of Engineering Association (Naczelna Organizacja Techniczna) for great technology achievements.