Showing papers by "Warren B. Jackson published in 1984"

Kinetics of the Staebler–Wronski effect in hydrogenated amorphous silicon

Abstract: We have investigated the time and intensity dependence of the creation process for light‐induced metastable defects (Staebler–Wronski effect) in hydrogenated amorphous silicon (a‐Si:H). The observed changes in electron spin resonance spin density (dangling bonds) and photoconductivity are consistent with a model which explains the Staebler–Wronski effect as a self‐limiting process intrinsic to a‐Si:H. A possible microscopic mechanism based on the nonradiative recombination of band tail carriers is discussed.

Chapter 3 Optical Properties of Defect States in a-Si: H

Abstract: Publisher Summary This chapter describes the utility of photothermal deflection spectroscopy (PDS) in obtaining information about the density of states in a-Si:H. The power of measuring optical absorption arises from the fact that it is a fundamental and well-understood process occurring in all solids. Typically, absorption measurements do not require contacts, doping conditions, Fermi-level positions, special temperatures, and device structures. The effect of almost any material parameter on the density of states can be assessed by measuring the effect of the parameter on the optical absorption. Photothermal deflection spectroscopy has proven to be a powerful tool for the investigation of very small optical absorptions. By overcoming the inherent limitations of conventional absorption techniques, PDS enables the direct and reliable determination of the energy and number of defects in a-Si:H. Furthermore, it is an excellent tool for the characterization of material parameters such as doping concentration, defect level, and film homogeneity.

Conduction-band density of states in hydrogenated amorphous silicon determined by inverse photoemission

Abstract: Identification d'une caracteristique 1,2-4 eV au-dessus du niveau de Fermi, qui pourrait etre associee a l'orbitale antiliante Si-H, d'apres son comportement au recuit et sa position en energie. Absence de structures de point critique

Charge transient and optical absorption measurements of characteristic gap states in phosphorus doped a-Si:H

Abstract: Recent electron capture experiments claim that the emission prefactor γ n decreases exponentially with trap energy and that the characteristic peak in the gap - state distribution of a - Si:H is ≈ 0.5 eV below the conduction band, rather than at ∼ 0.8 eV as found in other studies. Arguments are presented demonstrating that an exponential dependence of γ n on energy can result from an overly - simplified analysis of the trap filling process in a capacitance transient measurement. Furthermore, it is shown that within experimental uncertainty electrical and optical measurements yield the same peak densities over a range of phosphorus doping concentrations.