Intrinsic bonding defects in thin-film non-crystalline solids: Amorphous silicon (a-Si), hydrogenated amorphous silicon (a-Si:H), amorphous selenium (a-Se) and amorphous selenium–arsenic alloys (a-As x Se1− x )

Abstract

This article is dedicated to Professor Walter Spear and the many contributions he has made to the physics of transport phenomena in non-crystalline solids, including the development of the time of the flight technique for determining drift mobilities and trapping life-times in non-crystalline insulating and semiconducting solids. This technique has been applied to non-crystalline chalcogenides, including amorphous selenium (a-Se) and a-As–Se alloys, as well as a-Si, hydrogenated a-Si (a-Si:H) and microcrystalline silicon (μc-Si, more recently described as nanocrystalline, i.e. nc-Si). The thin-film materials addressed in this article have found applications in markedly different device technologies, and in each instance the research contributions of Professor Spear and his collaborators, initially at Leicester, and subsequently at Dundee, have played a significant role in providing a science base for understanding carrier transport and other properties that underpin device performance and reliability.