Amorphous Semiconductors: Structure, Optical, and Electrical Properties

This chapter is devoted to a survey of the structural, optical and electrical properties of amorphous semiconductors on the basis of their fundamental understanding. These properties are important for various types of applications using amorphous semicond

  • PDF / 1,855,184 Bytes
  • 16 Pages / 547.146 x 686 pts Page_size
  • 40 Downloads / 226 Views

DOWNLOAD

REPORT


This chapter is devoted to a survey of the structural, optical and electrical properties of amorphous semiconductors on the basis of their fundamental understanding. These properties are important for various types of applications using amorphous semiconductors. First, we review general aspects of the electronic states and defects in amorphous semiconductors, i.e., a-Si:H and related materials, and chalcogenide glasses, and their structural, optical and electrical properties. Further, we survey the two types of phenomena associated with amorphous structure, i.e., lightinduced phenomena, and quantum phenomena associated with nanosized amorphous structure. The former are important from the viewpoint of amorphous-silicon solar cells. The latter phenomena promise novel applications of amorphous semiconductors from the viewpoint of nanotechnology.

Amorphous semiconductors are promising electronic materials for a wide range of applications such as solar cells, thin-film transistors, light sensors, optical memory devices, vidicons, electrophotographic applications, X-ray image sensors, europium-doped optical-fibre amplifications etc, particularly, hydrogenated amorphous silicon (a-Si:H) for solar cells, thin-film transistors, X-ray image sensors, and chalcogenide glasses for optical memory devices including digital video/versatile disk (DVD). In this chapter, we emphasize the basic concepts and general aspects of the electronic properties of amorphous semiconductors such as their electrical and optical properties as well as their struc-

25.1

Electronic States .................................. 565

25.2 Structural Properties ............................ 25.2.1 General Aspects ........................ 25.2.2 a-Si:H and Related Materials ...... 25.2.3 Chalcogenide Glasses .................

568 568 568 569

25.3 Optical 25.3.1 25.3.2 25.3.3

Properties ................................ General Aspects ........................ a-Si:H and Related Materials ...... Chalcogenide Glasses .................

570 570 571 572

25.4 Electrical Properties ............................. 25.4.1 General Aspects ........................ 25.4.2 a-Si:H and Related Materials ...... 25.4.3 Chalcogenide Glasses .................

573 573 574 575

25.5 Light-Induced Phenomena................... 575 25.6 Nanosized Amorphous Structure ........... 577 References .................................................. 578

tural properties [25.1–3]. Furthermore, some basic and important results of these properties are described to understand these applications and to consider their further development. Light-induced phenomena in amorphous semiconductors, which have been considered to be associated with amorphous structure, are also described. Nanosized amorphous structures exhibit quantum effects associated with two-dimensional (quantum well), one-dimensional (quantum wire) and zero-dimensional (quantum dot) structures, so they have received significant attention on both the fundamental and application sides. These topics are briefly described.

25.1 El