The mixed non-saturating I-V characteristics of static induction transistor (SIT) are researched in this article, attempting to present the optimum matching relations among the structural, material and technological parameters. The technological experiments demonstrate that the channel parameters play a critical role in determining whether it is a mixed, triode-like or pentode-like I-V characteristics. The general control principles, methods and criterions of fabrication parameters as well as the effect of control factor beta are analytically discussed. The results are available and convenient for design and fabrication of SIT, especially for SIT with mixed I-V characteristics. (C) 2003 Elsevier Ltd. All rights reserved.