Tetrahedrally-bonded Amorphous Semiconductors Research Articles

Surface Microstructural Evolution of Ultrathin films by Real time Spectroscopic Elupsometry

ABSTRACTVapor deposition of smooth, microstructurally uniform amorphous films on dissimilar substrates requires coalescence of clusters that form during initial nucleation. We have developed techniques that provide sub-monolayer sensitivity to this phenomenon, relying on real time spectroscopie ellipsometry observations during ultrathin film growth (thicknesses < 50 Å). An investigation of tetrahedrally-bonded amorphous semiconductors lends insights into the role of nucleation density and adatom surface diffusion in determining the ultimate atomic-scale roughness on the film.

Status of a-Si technology and its applications to optoelectronics devices

Abstract A review is given on recent progress in tetrahedrally-bonded amorphous semiconductors and their technological applications to optoelectronic devices. First, some significant advantages of these materials are pointed out, and tangible instances are demonstrated from current technological topics. The present state of the art in optoelectronic device development with this new kind of thin film is then reviewed, and the technical data are summarized and discussed.

Book reviews

Book reviews

Recent progress of amorphous silicon technology and its application to optoelectronic devices

A review is given on recent progress in tetrahedrally-bonded amorphous semiconductors and their technological applications to optoelectronic devices. First, some significant advantages of these materials are pointed out, and tangible instances are demonstrated from current technological topics. The present state of the art in optoelectronic device development with this new kind of thin film is then reviewed, and the technical data are summarized and discussed.

Recent progress of amorphous silicon technology and its application to optoelectronic devices

A review is given on recent progress in tetrahedrally-bonded amorphous semiconductors and their technological applications to optoelectronic devices. First, some significant advantages of these materials are pointed out, and tangible instances are demonstrated from current technological topics. The present state of the art in optoelectronic device development with this new kind of thin film is then reviewed, and the technical data are summarized and discussed.

Local structure study of tetrahedrally-boned amorphous semiconductors by NMR, ESR and Raman spectroscopies

Results of NMR, ESR, Raman scattering and infrared absorption measurements are correlated for tetrahedrally-bonded amorphous semiconductors including SiN and SiC. It is found that dangling bonds are produced in order to relax the local strain due to overconstrained fourfold coordinated structure and the density of them is reduced by the presence of randomly distributed onefold coordinated H atoms which reduces the local strain. On the other hand of Si into amorphous Si network increases the local strain, resulting in an increase in the density of dangling bonds.

Magnetic Resonance Studies on Tetrahedrally Bonded Amorphous Semiconductors

Magnetic Resonance Studies on Tetrahedrally Bonded Amorphous Semiconductors

A Theoretical Approach to the Electronic Structure of Tetrahedrally-Bonded Amorphous Solids

On the basis of a simple method by which quantitative disorder as well as topological disorder in amorphous solids can be treated systematically, we study the electronic density of states of tetrahedrally-bonded amorphous semiconductors such as amorphous silicon or germanium. We adopt the Weaire-Thorpe model and apply the coherent potential approximation to the random variations of the banding parameter V 1 and the bonding parameter V 2 of this model. It is possible to explain the disappearance of the dip between the two lower peaks of the valence band by introducing fluctuations in V 1 alone. This fact indicates that it is not always necessary to assume the existence of five-membered rings as a cause for the disappearance of the dip. We also discuss the effects of fluctuations in V 2 , missing atoms and broken bonds.

Far Infrared Absorption by Tetrahedrally Bonded Amorphous Semiconductors

A discussion of the electronic structure of amorphous semiconductors is given and the ideas are developed for the case of the tetrahedrally bonded elements silicon and germanium. This background is used to interpret far infrared conductivity data taken in our laboratory. The results suggest that the void structure in these materials plays a central role in the photon-vibration coupling, particularly at low frequencies.

Effects of quantitative disorder on the electronic structure of tetrahedrally-bonded amorphous semiconductors

We have studied the effects of quantitative disorder on the valence band in the electronic density of states (DOS) of tetrahedrally-bonded amorphous semiconductors on the basis of a simple Weaire-Thorpe model. The coherent potential approximation is applied to the random variation of the transfer integrals V 1 and V 2 of the model. Our numerical results indicate that it is not always necessary to assume the existence of five-membered rings in order to explain the characteristic features of the DOS.