The Field Effect Transistor

Two papers have already appeared on the field-effect transistor, 1 ' 2 in which the basic features of the theory were presented and their experimental verification discussed. This present paper describes certain additions to the theory and the experimental verification thereof which arise when attempts are made to realize the ultimate in high-frequency performance. In particular the effect of non-constant mobility at high 1149 1150 T H E BELL SYSTEM TECHNICAL J O U R N A L , NOVEMBER 1955 electric fields is analyzed in some detail and shown to be a governing consideration for some designs. An attempt has been made to make the present paper sufficiently complete that it will not be necessary to refer to the previously published literature. For that reason certain of the previously published results are quoted as a starting point for the extended theory. The paper is divided into two parts. The first part presents the complete theory as of its present state of development, and the second part describes the most recent advances in the experimental verification of this theory. PART I, 2. A QUALITATIVE THEORY THEORY