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GaN-based Tunneling Hot Electron Transfer Amplifier (THETA)

Tunneling hot electron transfer amplifier (THETA) is a vertical unipolar transistor consisting of emitter tunneling barrier, highly doped base layer and collector. Electrons are tunnel-injected ballistically, and transmitted over the base-collector barrier at sufficient energy. The device was originally invented by M. Heiblum et al. in III-As system. However, due to the fundamental limitations of III-As materials such as small band gap, band offset and valley seperations, the device was hard to operate at room temperature.

In III-nitride system, we demonstrated the first tunneling hot electron transfer amplifier with common emitter gain and high current transfer ratio at room temperature. We also observed repeatable double-sweep negative differential resistance with high peak-to-valley current ratio at room temperature.

Because of ultrafast tunneling injection and ballistic transport, the intrinsic delay of such device is less than 120 fs operated at sufficient bias (>1V), which is promising for THz applications.


1) D. N. Nath, Z. C. Yang, C.-Y. Lee, P. S. Park, Y.-R. Wu, and S. Rajan, “Unipolar Vertical Transport in GaN/AlGaN/GaN Heterostructures.” Applied Physics Letters 103 (2) (2013).

2) Digbijoy N. Nath, Zhichao Yang, Pil Sung Park, and Siddharth Rajan, "III-nitride Tunnel Injection Hot Electron Transfer Amplifier(THETA) with Common-emitter Gain", International Semiconductor Research Conference (ISDRS) December, 2013.

3) Zhichao Yang, Digbijoy Nath, and Siddharth Rajan, “Negative Differential Resistance in GaN-based Tunneling Hot Electron Transistor at Room Temperature”, 56th Electronic Material Conference, submitted (2014).