Generation of Electromagnetic Oscillations of Submillimeter Range by GazIn1 – zAs Diodes Using Impact Ionization

Abstract

Development of millimeter and terahertz wave ranges is one of the main objectives of modern highfrequency electronic devices. However, there are not many active elements able to operate in these ranges. Transferred electron devices (TED) still remain a more widespread compact electromagnetic wave sources. But oscillation efficiency of TED operating in the submillimeter wave range is small and, in most cases, generation becomes impossible. Difficulties in obtaining maximum frequencies are mainly determined by the electron transition time from the upper valley to the lower one. The aim of the work is to investigate reduction of the transition time problem by using band to band impact ionization. The paper deals with charge transport in short diodes with InzGa1-zAs-based graded band structure with the active region length of 0.64 m. Doping concentration in the n-type active region was 10 16 …8•10 16 cm-3. Ensemble Monte-Carlo Technique is carried out to describe the charge carrier dynamics in the device. A three-valley conduction band and heavy hole band ГV1 are taken into account. It is shown a possibility of using localized impact ionization as an energy relaxation mechanism. Correlation between the number of acts of impact ionization and decrease in electron number in the upper va lleys are demonstrated. Oscillation efficiency of the diodes is calculated. It is shown that impact ionization can lead to increase in the maximum generation frequency. The proposed way of improving frequency properties due to modification of electron transfer near the anode contact can be applied to short structures and allows maximum generation frequencies.

Advanced Micron Sized Gunn Diode Based on Graded-Gap GaPAs – GaInAs

“…The research results are consistent with similar studies [11,[14][15][16][17][18][19][20]. In recent years, planar Gunn diodes have shown consistent improvements in frequency [15][16][17][18][19].…”

“…self-oscillations. It should be noted that, as shown by the research results [6,10,14], such devices have RF power when operating in a resonator.…”

“…Current oscillations in the 01027-4 diode occur at any mole fraction of In. If the mole fraction of In is greater than 0.6, then the intervalley electron transfer effect is overlapped by impact ionization [12][13][14]. Impact ionization is considered a negative effect for transfer electron devices.…”

“…Impact ionization is considered a negative effect for transfer electron devices. However, research [14] shows that if impact ionization occurs only in the anode contact, then the oscillation frequency increases. A diode with an active zone length of 0.64 μm based on the graded-gap GaAs -Ga0.2In0.8As alloy has a peak of efficiency at 210 GHz with impact ionization and at 150 GHz without impact ionization.…”