Indium phosphide-Langmuir film MIS devices
Langmuir Blodgett films are an interesting example of two dimensional order structure. Their fabrication involves the building-up of a multilayer firmly repeated deposition of single monomolecular layers upon the substrate material. The resultant structure is of defined thickness and excellent uniformity. Because of these qualities, Langmuir films enjoy potential applicatons in many areas of modern science. In particular , their excellent insulating properties have led to the proposition of their use within the semiconductor device industry. Indium phosphide, although a relatively new semiconductor, is already becoming an important device material, particularly in areas where its high mobility gives rapid device response and good high frequency operation. This thesis combines these two materials, and looks at the electrical behaviour of InP/Langmuir film metal-insulator-semiconductor (MIF devices and their associated structures). The Langmuir-Blodgett process is a low temperature deposition technique, and thus induces little or no surface damage to its recipient substrate. Because of this, it is likely that the chemical surface of the InP, prior to deposition, will be of critical importance in defining the device characteristics. This has in fact been found to b'. the case, and a detailed study of the correlation between ESCA surface chemical information and vice electrical data has been undertaken. In addition, the device results obtained have been found be rather different to those produced by the use of a conventional high temperature deposition process. In order to capitalise upon the use of these organic insulating films, and the sensitive nature of the InP surface, the effect of various gases upon these device structures have been investigated. The study has revealed the existence of many interesting bulk and interface effects, and is likely to form the basis of a more detailed programme aiming to develop a range of solid state sensors.