Electrical characteristics of SRO-miss devices and their applications

Abstract

The electrical characteristics of the Metal-Insulator-Semiconductor - Switch (MISS) device with Silicon-Rich-Oxide (SRO) as the semi-insulating material have been comprehensively studied at room temperature in an exploratory way. The SRO films were deposited by atmospheric pressure chemical vapour deposition (APCVD) at 650ºC with SiH(_4) and N(_2)O reactant gases and N(_2) carrier. The react ant gas phase ratio R(_o) varying from 0.09 to 0.25 and the deposition time varying from 0.6 to 2 min. Some preliminary investigations on SRO-MIS devices were also carried out in order to understand the electronic process in the structure. Various parameters which governed the switching behaviour of an MISS were investigated. In general the switching characteristics are similar to those of the tunnel oxide MISS. The geometrical dependence of the switching behaviour in the tunnel oxide MISS has been extended to the present device by looking at the effects of electrode area, junction area, electrode perimeters and of a metal guard ring. Other effects, such as SRO deposition time, work function difference, gold doping, heat treatment, light illumination and film ageing were also observed. The dynamic characteristic of the device was studied using a double pulse technique. The characteristics of the three-terminal SRO-MISS were studied in both forward and reverse bias. The former exhibited a thyristor-like characteristic and the latter a transistor-Hke characteristic. A preliminary study on the MIS-emitter transistor was carried out with different emitter areas. In general the characteristics are the same as for the equivalent tunnel oxide devices. However it was also found that if the n-type epilayer is very thin the transistor characteristics exhibits an N-type negative resistance. The negative resistance region of the two-terminal MISS has been shown to be stable and the stability has been analysed in terms of equivalent circuit elements. The reason for the stability is that the device also has an negative capacitance. This has been proved experimentally and it is a new property of the MISS structure which never been reported before. The negative capacitance has been measured as a function of electrode area, SRO type and light illumination. An important circuit application for the negative capacitance has also been suggested and demonstrated