N. Orihashi

One THz harmonic oscillation of resonant tunneling diodes

One THz harmonic oscillation was observed in a sub-THz oscillating GaInAs∕AlAs resonant tunneling diode integrated with a slot antenna. The fundamental and third-harmonic frequencies were 342GHz and 1.02THz, respectively, for a 50μm long antenna. The maximum output power of the fundamental mode was around 23μW, and that of the third-harmonic component was 2.6% of the fundamental. Theoretical analysis with the van der Pole equation qualitatively explained the measured results.

Experimental and Theoretical Characteristics of Sub-Terahertz and Terahertz Oscillations of Resonant Tunneling Diodes Integrated with Slot Antennas

Experimental and theoretical characteristics of sub-terahertz and terahertz oscillations in resonant tunneling diodes (RTDs) integrated with slot antennas are reported. In the experiments, oscillations up to 0.6 THz were obtained in GaInAs/AlAs double-barrier RTDs. The oscillation characteristics were theoretically analyzed for the total device structure including RTD and slot antenna. The equivalent circuit with all parasitic elements was taken into account for the RTD, and the actual structure of the antenna was analyzed using a three-dimensional electromagnetic simulator. The theoretical analysis was in good agreement with the measurements of oscillation frequency and output power. It was shown from the theoretical results that the RTD itself has the potential to oscillate up to 3.0 THz, and that the RTD oscillator with slot antenna is able to oscillate up to 2.8 THz if the device structure is optimized. The output power analysis showed that 90 µW at 1 THz is possible by optimizing the device structure.

Mutual injection locking between sub-THz oscillating resonant tunneling diodes

Mutual injection locking was observed for sub-THz oscillators consisting of GaInAs/AlAs resonant tunneling diodes integrated with slot antennas. Two oscillators with the individual frequencies of 340 GHz and 324 GHz on the same wafer were driven simultaneously. Oscillation at a single line of 330 GHz was obtained with summed output power.

Millimeter and submillimeter oscillators using resonant tunneling diodes with stacked-layer slot antennas

We proposed a resonant tunneling diode (RTD) oscillator with a stacked-layer slot antenna toward the terahertz range, and demonstrated 254 GHz oscillation with GaInAs/AlInAs RTD. Theoretical analysis for oscillation frequency of the fabricated device was in reasonable agreement with the measurement. Higher oscillation frequency is expected by reducing the slot length.

Mutual Injection Locking between Sub-THz Oscillating Resonant Tunneling Diodes

Mutual injection locking was observed for sub-THz oscillators consisting of GaInAs/AlAs resonant tunneling diodes integrated with slot antennas. Two oscillators with the individual frequencies of 340 GHz and 324 GHz on the same wafer were driven simultaneously. Oscillation at a single line of 330 GHz was obtained with summed output power.

Experiment and Theoretical Analysis of Voltage-Controlled Sub-THz Oscillation of Resonant Tunneling Diodes

Experimental result and theoretical analysis are reported for bias-voltage dependence of oscillation frequency in resonant tunneling diodes (RTDs) integrated with slot antennas. Frequency change of 18 GHz is obtained experimentally for a device with the central oscillation frequency of 470 GHz. The observed frequency change is attributed to the bias-voltage dependence of the transit time of electrons across the RTD layers, which results in a voltage-dependent capacitance added to RTD. Theoretical analysis taking into account this transit time is in reasonable agreement with the observed results. Voltage-controlled RTD oscillators in the terahertz range are expected from the theoretical results. A structure suitable for large frequency change is also discussed briefly.

Voltage-Controlled Harmonic Oscillation at About 1 THz in Resonant Tunneling Diodes Integrated with Slot Antennas

Frequency change with bias voltage was observed in the third harmonic oscillation at about 1 THz in GaInAs/AlAs double-barrier resonant tunneling diodes integrated with slot antennas at room temperature. The oscillation frequency changed from about 0.96 to 1.02 THz. Results of theoretical analysis were compared with those of measurements using a simple equivalent circuit with an additional capacitance due to bias-voltage-dependent tunneling time of electrons, and a reasonable agreement was obtained.

Frequency mixing characteristics of room temperature resonant tunneling diodes at 100 and 200GHz

Frequency mixing characteristics are examined for room temperature resonant tunneling diodes at 100GHz in the fundamental mode and at 200GHz in the second harmonic mode. At the peak voltage of the dc I‐V curves, the output signal level was the highest for fundamental mixing and the lowest as a dip for second harmonic mixing. Experimentally obtained data are compared with the values calculated by a circuit analysis with finite sinusoidal voltage swings. The results indicate that the experimental results are in good agreement with the numerical predictions without capacitance for detection, fundamental mixing, and second harmonic mixing. Particularly, mixing characteristics with large input power, which cannot be treated by small signal analysis, are well explained by the model used here.

Millimeter and submillimeter oscillator using resonant tunneling diode and slot antenna with a novel RF short structure

We proposed a resonant tunneling diode (RTD) oscillator using a slot antenna with a novel RF short structure toward terahertz range, and demonstrated the oscillations up to 587 GHz with GaInAs/AlAs double-barrier RTD. Theoretical analysis for oscillation frequency of the fabricated device was in very good agreement with the measurement. Higher oscillation frequency beyond 1 THz is expected by reducing the antenna size.

Experimental and theoretical characteristics of sub-THz and THz oscillation of resonant tunneling diode integrated with slot antenna

Sub-THz and THz oscillation of resonant tunneling diodes integrated with slot antennas is investigated. Oscillation frequency of 587 GHz in the experiment agrees very well with theoretical analysis which indicates possibility of oscillation up to 1.4 THz by reducing antenna size. Output power of 50 /spl mu/W around 1 THz is also estimated theoretically.