Symmetry of the real-space transfer and collector-controlled states in charge injection transistors

Abstract

The charge injection transistor, or CHINT, is a three-terminal semiconductor device based on controlled real-space transfer of hot electrons between two conducting layers separated by a potential barrier. The symmetry of hot-electron injection by real-space transfer with respect to the polarity of the heating field allows the implementation of novel circuit elements. Thus, in the basic CHINT structure, the collector current is an exclusive OR function of voltages applied to the emitter electrodes. Moreover, the authors have proposed and demonstrated a multiterminal device structure with three symmetric logic inputs that performs both the NOR and the AND logic functions, and can be switched between these functions in the course of the circuit operation. Symmetry properties of real-space transfer transistors have been studied theoretically, with the help of continuation modeling and transient device simulation. These studies reveal a variety of instabilities and a striking novelty of multiply connected current-voltage characteristics. The authors have found that the CHINT can support anomalous steady states in which hot-electron injection occurs in the absence of any voltage between the emitter electrodes. In these states, some of which are not only stationary but also stable with respect to small perturbations, the electron heating is due to the fringing field from the collector electrode. Some of the anomalous states break the reflection symmetry in the plane normal to the channel at midpoint. The study elucidates the formation of hot-electron domains.