Theoretical study of terahertz active transmission line oscillator based on RTD-gated HEMT

Abstract

In this paper, a new kind of terahertz oscillator is presented using plasma wave excitation in a resonant tunnel diode (RTD) gated high electron mobility transistor (HEMT). The plasma wave arising from the RTD-gated HEMT is equivalent to active transmission lines and induces negative differential conductance (NDC) of the oscillator. The proposed RTD-gated HEMT oscillator is more compact and has higher oscillation frequency than the transmission line loaded traditional RTD oscillator duo to plasma wave effect. This paper analyses and calculates the oscillation conditions, the relationships between device structures, oscillation frequency and the output power of the oscillator. The presented work may provide a new concept for fabricating terahertz oscillator.

Resonant Tunneling Diode (RTD) Terahertz Active Transmission Line Oscillator with Graphene-Plasma Wave and Two Graphene Antennas

“…I-V characteristic of RTD which was simulated by WINGREEN is shown in Figure 1d. This is a N-type NDR, and g is called negative difference conductor (NDC) which is defined as [16]…”

“…As shown in Figure 1d, ∆I = 29 mA/µm 2 and ∆V = 0.7 V. The RTD oscillator is biased at 0.7 V at NDR region. According to reference [14,16,17], Equation (3) can be assumed as…”

“…Moreover, the fabrication of high frequency RTD oscillator remains challenging.In [13], Burke et al developed the high-frequency transmission line model to describe a metal-gate/insulator/two-dimensional electron fluid (2DEF) structure. Then, the model was used in THz power amplification via plasma wave excitation [14,15], high-electron-mobility transistor (HEMT) with RTD gate [16], and photo-controlled THz amplified modulator [17]. In the previous study, a graphene layer was employed for plasma wave excitation [18][19][20][21].…”

“…Secondly, output power increase is not only due to the increase in device size, but also due to a graphene layer which produces RTD-gated-graphene-2DEF and the negative differential resistance (NDR). According to references [14,16,17], two-dimensional electron fluid (2DEF) is required to realize power amplification, which is produced by RTD-gated HEMT with very complicated layered structure. Because the films thickness of the RTD-gated HEMT are very small, only a few nanometers, so the molecular beam epitaxy [19,22,23] or metal-organic chemical vapor deposition [24] is required [25].…”

Oscillations up to terahertz frequency in resonant tunneling diodes

“…However, the low operating temperature of QCLs mainly affects its performance. Hetero‐bipolar transistors (HBTs), silicon complementary metal‐oxide semiconductors (Si CMOS), high electron‐mobility transistors (HEMTs) and resonant tunneling diodes (RTDs) have also been extensively investigated as THz sources . In electron devices, RTDs are promising candidates for THz sources at room temperature …”