Polycrystalline silicon thin film transistors

Abstract

During the past decade there has been a rapid growth of interest in poly-Si for the active device layer in thin film transistors (TFTS) for active matrix flat-panel displays. Whilst the early work, demonstrating the high carrier mobility of these devices, employed processing temperatures of -1000 "C and quartz substrates, this was soon followed by the investigation of lower-temperature processes which were compatible with the use of glass substrates. Some of the key aspects of this work are reviewed in this article: the preparation of the material by direct deposition and by crystallization from a-Si precursors, the characterization of the defect-induced trapping states within the material and their passivation, and the present understanding of the TFT leakage current mechanisms. This work is put into the context of the requirements for active matrix liquid-crystal displays, and, with the understanding and control of poly-Si which has been achieved to date, its application in this area can be expected to increase rapidly in the coming years.

Electrical properties of pulsed UV laser irradiated amorphous carbon

“…12 Pulsed UV laser annealing has been used to crystallize hydrogenated amorphous silicon. [13][14][15] The merit of pulsed laser annealing ͑PLA͒ with UV photons is that the laser is absorbed close to the surface and the effect to the substrate is minimal compared to thermal annealing in a furnace.…”

Capas de SiGe policristalino hidrogenado y su aplicación en transistores de película delgada

“…La capa activa de los transistores es una película delgada de material semiconductor, normalmente Si, depositada sobre el sustrato vítreo usado para la fabricación de la pantalla [1]. Un material de interés para la realización de la capa activa es el SiGe policristalino obtenido por cristalización en fase sólida de una película amorfa depositada mediante un sistema de depósito químico en fase vapor a baja presión (LPCVD).…”

Microscopic Origin for Electrically Benign Small-angle Grain Boundaries in Low-cost Semiconductors

“…[1] However, considering the large-area required for the solar cell and flat panel display, such a single-crystal substrate is too expensive to be practical. As a consequence, polycrystalline semiconductor films, [2,3] grown on non-crystalline substrate such as glass have emerged as an important alternative.…”

“…[2] In thin-film transistors (TFTs), charge trapping at the GBs will result in band bending and consequently undesirable mobility barriers. [3] In general, the ability to fabricate low-temperature, yet low-defect density polycrystalline semiconductors on glass or plastic, is crucial for the development and commercialization of low-cost solar cells, TFTs, and micro-electromechanical systems.…”