Improved Negative Differential Resistance Characteristics in Surface Tunnel Transistors

Abstract
We propose and demonstrate a new type of Surface Tunnel Transistor (STT) which displays improved negative differential resistance (NDR) characteristics. In this device, called channel-doped STT (CD-STT), the channel region is direclly doped with donors in order to increase the channel carrier density. A peak current is obtained that is 103times larger than that of a conventional STT. To reduce the valley current further, a blocking layer consisting of an i-GaAs is inserted at the gate/drain overlap region. The resulting device, called blocking layer inserted STT (BLI-STT), exhibits excellent NDR characteristics with a peak-to-valley ratio (PVR) of 4.8 at room temperature, a value which is more than 4 times larger than that of a conventional STT.