Compensating Piezoelectric Effect of Gate Metal and Dielectric Overlayer Stresses on GaAs MESFETs

概要

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The orientation dependence of the threshold voltage V_T of GaAs MESFETs before and after passivation with a SIN_x overlayer was investigated. [001] and [010] oriented FETs have the same V_T which does not change after passivation. [011] and [011] oriented FETs show opposite V_T shifts relative to the [001] FETs. The sign of the shift is reversed by passivation. The measured stresses in the gate metal and dielectric overlayer are both tensile. A model of the piezoelectrically induced charges is extended to include the effects of both the gate metal and dielectric overlayer. Using the measured stress values, a good conformity between experimental results and model calculations is obtained. In particular it is demonstrated that the same stress in both layers produces piezoelectric charges of opposite sign in the MESFET channel region.
社団法人応用物理学会の論文
1987-10-20