Amorphous Semiconductor Devices Research Articles

Simulated time-of-flight experiments across abrupt and graded shifts in a band edge

Abrupt or graded changes in the position of a band edge relative to the vacuum level occur where there is an abrupt or gradual change in the composition of the material in an amorphous semiconductor device. These shifts in the band edge are very useful in α-Si:H solar cells and other devices, but many questions remain regarding their physical nature and how carriers traverse them. This paper presents simulations of time-of-flight experiments across both gradual and abrupt shifts in the edge of the band in which carriers are traveling. These experiments should be able to help determine the effects of these shifts on carrier transport. The effects of a band tail on simulated transients are also shown.

Gallium Arsenide and Silicon Optical Assemblies: An Advanced Glass-Polymer-Semiconductor Adhesion Process

AbstractA simple adhesion process has been developed for applying glass lenses to the active surfaces of Si and GaAs optical devices such as detectors and solar cells [1]. The method, which uses a film of fluorinated ethylene propylene (FEP) offers reliability, cost and throughput advantages over the conventional dimethyl silicone adhesive. Critical to the process is the ion bombardment of individual surfaces before assembly. The resulting enhanced adhesion suggests some modification of surface properties. Four possible mechanisms are briefly discussed. The technique is believed to have broad applicability to amorphous and crystalline semiconductor systems and devices other than those under test.

Transient Response of Amorphous Semiconductor Devices: A Theoretical Microscopic Simulation Approach to the Physics of Disordered Systems

Transient Response of Amorphous Semiconductor Devices: A Theoretical Microscopic Simulation Approach to the Physics of Disordered Systems

Amorphous Semiconductor Technologies and Devices 1982: Japan Annual Reviews in Electronics, Computers and Telecommunications Vol 2

These books are part of a new series on recent developments in electronics, computers and telecommunications in Japan (the other two volumes deal with optical devices and fibers (sic) and computer science and technologies). Volume 1 covers recent developments in 'Semiconductor technologies'.

Book review

Book review

Amorphous Semiconductor Technologies and Devices

Amorphous Semiconductor Technologies and Devices

Possibilities of Amorphous Semiconductor Devices

Possibilities of Amorphous Semiconductor Devices

Review of conductor-insulator-semiconductor (CIS) solar cells

The physics and technology of a new class of photovoltaic devices, namely the conductor-insulator-semiconductor (CIS) solar cells, are reviewed in this paper. The top layer in these diodes may be a transparent conducting metal film, an oxide or polymer semiconductor, an electrolyte or a combination of these, leading to a wide variety of metal-insulator-semiconductor (MIS), semiconductor-insulator-semiconductor (SIS) and electrolyte-insulator-semiconductor (EIS) structures. The thickness of the interfacial layer and the work function of the conductor are the important parameters in the optimization of these devices. By ensuring inversion at the interface of the base semiconductor, devices can be fabricated with properties which do not depend strongly on the surface states nor on other non-idealities of the interfacial layer. CIS solar cells with efficiencies comparable with the best p-n junction cells have been fabricated. Most of the presentation is related to single-crystal devices, and the non-crystalline (polycrystalline and amorphous) semiconductor devices are treated separately. Available stability and accelerated life test data indicate fairly stable operation of optimized devices. It is suggested that the research and development efforts have reached such a stage that a prototype production facility is viable.

Amorphous Semiconductor Devices: Memory and Switching Mechanism

This paper reports the study of amorphous semiconductor devices of memory and threshold types. Measurements have been made on As Ge10 Te90- glasses, silver dpoed As10 Ge15 Te75 glass with silver concentrations from 0 to 10.0 at.% and Se20 Ge20 Te60 and Se20 Ge20 T55 glasses. The I—V characteristics in the OFF state of the materials have been studied at temperature 30,50, 60, 80 and 100°C. The threshold voltages of switching and their variation with temperature, composition and silver content have been studied. Measurements reveal that (i) the I—V characteristics over a wide range of temperature can be normalized into a single curve, (ii) the threshold voltage of switching decreases exponentially with the increase of temperature, (iii) the ratio of activation energy of dc conductivity to that of switching is of the order of two for all these glasses, (iv) the threshold voltage of switching is well correlated with the glass transition temperature, (v) Silver doping does not change the basic behaviour of As-Ge-Te glasses, and (vi) the switching mechanism in both memory and threshold devices studied, appears to be initiated by a thermal process with possible electronic contribution.

The on-state of the amorphous semiconductor device

A simple relaxation analysis is presented to show that the transient on characteristics of the amorphous semiconductor device are consistent with bulk filament characteristics.

Amorphous semiconductor devices and components

The first part of this review describes, in terms intended for the general reader, the physical basis of amorphous semiconductors and their use in switching devices. The second part is devoted to a more critical appraisal of current thinking on conduction and switching mechanisms and recent advances in the technology and applications of amorphous semiconductor devices.

Effects of microstructure on the radiation stability of amorphous semiconductors

The influence of phase separated and crystalline regions on the fast neutron and X-ray damage thresholds of germanium chalcogenides and vanadia-phosphate semiconducting glasses has been established. Damage thresholds are shown to be a function of volume fraction and size of heterogeneities, and the bond energies of the glass. A theoretical model interpreting structure-dependent radiation damage is presented based on heterogeneous semiconductor theory and the destruction of interfacial Schottky barriers. Applications of the results to predicting the radiation sensitivity of amorphous semiconductor devices are suggested.

Device structures and fabrication techniques for amorphous semiconductor switching devices

The history of structures developed at ecd for amorphous switching and memory devices is outlined and traced from the original bulk contact structure to the present all-film photo-etched devices. The types of geometries used to cover the voltage range 2–200 V are discussed. The causes for instabilities observed in some amorphous semiconductor devices are analysed. The factors influencing yield of devices are discussed with specific reference to experience on arrays of 2500 devices per square inch.

Several circuit applications of amorphous semiconductors

The incorporation of amorphous semiconductor devices in several circuit applications is presented considering such aspects as linear amplification, ternary threshold logic, and clocked binary gates. The circuit descriptions are brief in favor of presenting the principles of operation. Detail design data are available from laboratory reports and published papers appropriately cited in the paper. Working laboratory models were “breadboarded” for each of the circuits, however, it is cautioned that a hand selection of devices was required. Furthermore, no attempt in optimization was made. It is believed that with modification, while retaining basic principles considerable improvement in circuit performance can be achieved. It may be that crystalline semiconductor devices would avail circuits usually simpler in concept and design than those which are described here. However, the virtues of the circuits discussed herein, lie in their novelty as an application of new circuit elements that may yield ideas for improving their methods of application or give insight into new methods of employing these devices.