Operation of resonant-tunneling diodes with strong back injection from the collector at frequencies up to 1.46 THz

Abstract

In search for possibilities to increase the operating frequencies of resonant-tunneling diodes (RTDs), we are studying RTDs working in an unusual regime. The collector side of our diodes is so heavily doped that the collector depletion region is fully eliminated in our RTDs and the ground quantum-well subband stays immersed under (or stays close to) the collector quasi-Fermi level. The electron injection from the collector into the RTD quantum well is very strong in our diodes and stays comparable to that from the emitter in the whole range of RTD operating biases. Our RTDs exhibit well pronounced negative-differential-conductance region and peak-to-valley current ratio around 1.8. We demonstrate operation of our diodes in RTD oscillators up to 1.46 THz. We also observe a fine structure in the emission spectra of our RTD oscillators, when they are working in the regime close to the onset of oscillations.

Measurements of temperature characteristics and estimation of terahertz negative differential conductance in resonant-tunneling-diode oscillators

“…[4][5][6][7] Operating frequency of oscillators with electron devices has also been rapidly increasing from the millimeter wave side. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Among the electron devices, resonant tunneling diodes (RTDs) have been considered as one of the candidates for compact THz oscillators at room temperature. [16][17][18][19][20][21][22][23] Oscillations up to 1.98 THz 23 and relatively high output power in the sub-THz region 24 have been reported for these oscillators.…”

Negative differential resistance devices for generation of terahertz radiation

“…Contrary to the first experimental demonstration of oscillations up to 712 GHz, these state-of-the-art oscillators used InGaAs/AlAs double barrier RTDs on InP substrate. Examples of their record performance are 0.2 mW at 443 GHz [9], 5 µW at 1.53 THz, and operation up to 1.55 THz [10], [11].…”

“…In addition, the oscillation spectra were determined with a Fourier transform infrared (FTIR) spectrometer. Such FTIR spectrometers typically have a resolution limit of many GHz and the spectra of free-running RTD oscillators, for example, shown in [10] have "linewidths" of 10-25 GHz. This is in a stark contrast to free-running oscillators with GaAs tunnel-injection transit time (TUNNETT) diodes, InP Gunn devices, and GaAs/AlAs SLEDs that all show linewidths orders of magnitude smaller than those of RTDs.…”

“…However, the total emitted output powers were extrapolated from measurements with a bolometer by taking into account the radiation pattern and spill-over of the hemispherical silicon lens [9], [10]. They have not been ascertained with a calibrated calorimeter such as the quasi-optical Thomas-Keating power meter [12].…”

Temperature tuning from direct to inverted bistable electroluminescence in resonant tunneling diodes

“…Although fundamentally based on the quantum mechanical tunneling effect, they are devices suitable for room temperature applications 4,5 , e.g. RTDs can be found in high frequency oscillators up to the THz regime 6,7 , (hot electron) tunneling transistors 8,9 and logic gates 10 . Such richness emerges from a low dimensional and typically just a few nm thick active region in combination with the region of negative differential conductance.…”