Author: Poul-Erik SchmidtPublisher:
ISBN:
Category :
Languages : en
Pages : 176
Book Description
This work is devoted to the study of Semiconductor Insulator Semiconductor Field Effect Transistors (SISFET), a promising device for integrated circuits, since very good threshold voltage control and uniformity can be obtained, and it should be possible to realize complementary circuits. During this work we have for the first time successfully grown and processed pseudomorphic GaAs/GalnAs/A1GaAs SISFET.From electrical measurements and modelling the residual doping level, and the effective barrier height of the A10.4Ga0.6As barrier layer has been deduced. Photoluminescense measurements have been performed on the pseudomorphic structures in order to determine the Indium content of the GainAs layer.A self-aligned technology has been established in order to fabricate high performance devices. The process includes first an anisotropic etch of the gate using Reactive Ion Etching. Next a silicon nitride sidewall is formed. A self-aligned ion implantation followed by rapid thermal annealing is used to form highly doped source and drain contacts. DC characterizations are presented. For 1μm SISFETs state-of-the-art results have been obtained, with a transconductance of 240 mS/mm. The transconductance of the pseudomorphic SISFET is even higher with a maximum value of 273 mS/mm. Our SISFET's have a source resistance of only 0.16 Ωmm which is the lowest ever reported. A very good on-wafer threshold voltage uniformity has been obtained with a standard deviation of only 11mV for the conventional SISFETs.Hot electron effects have been observed and are discussed. We show that this induces a negative differential resistance regime in the the drain current characteristics