Enhanced Electrical Properties of Optimized Vertical Graphene-Base Hot Electron Transistors

Abstract

The arrival of high-mobility two-dimensional materials like graphene leads to the renaissance of former vertical semiconductor–metal–semiconductor (SMS) hot electron transistors. Because of the monolayer thickness of graphene, improved SMS transistors with a semimetallic graphene-base electrode are now feasible for high-frequency applications. In this study we report about a device that consists of amorphous silicon, graphene, and crystalline silicon. For the first time, this device is fabricated by a four-mask lithography process which leads to significant improvements in the device performance. A strongly increased common-emitter current gain of 2% could be achieved while the on–off ratio improved to 1.6 × 105, which is already higher than predicted theoretically. This could be mainly attributed to better interface characteristics and decreased lateral dimensions of the devices. A cutoff frequency of approximately 26 MHz could be forecasted based on the DC measurements of the device.

High Gain Graphene Based Hot Electron Transistor with Record High Saturated Output Current Density

“…In Table 2 selected HET devices from different reports and their performance parameters J C and 𝛼 max are compared. [7,8,14,[18][19][20][21][22][23] The devices are ordered by the achieved output current density J C . Most of the HETs utilize a tunnel barrier at the emitter-base junction.…”