A ferroelectric field effect device

A new device is described, based on a much older but little-known experimental technique. Basically, the device is a thin film transistor with a ferroelectric gate insulator (hereafter referred to as FEFED for ferroelectric field effect device). This combination produces a device whose drain current-gate voltage characteristic reproduces the hysteresis character of the ferroelectric gate insulator. The unusual and useful characteristic results from the fact that the polarization charge of the ferroelectric is at least partially compensated by free charge in the semiconductor. Once polarized, the ferroelectric, ideally, maintains itself in this condition even while short-circuited, and this is reflected in the level of current in the adjacent semiconductor. Intermediate current levels between those determined by the positive and negative saturation polarization are accessible by limiting the charge available for switching. The device is capable of multi-level storage with continuous nondestructive readout. Readin as well as readout times can be in the microsecond range. A description of the device fabrication techniques as well as its characteristics, performance, and problems at this time are some of the topics which will be covered in detail.